Professional Partner for Measure &amp; Control

The general liquid nitrogen tank can have its own liquid level indicator.
Some industrial liquid nitrogen storage tanks, without liquid level display, can be equipped with our very low temperature liquid nitrogen liquid level sensor. Local display is supported. At the same time, it supports signal output, which can be connected to the recorder or the user’s monitoring system.

Extended reading: Nitrogen Gas Rotameter

The design temperature of the liquid nitrogen tank is -196°C. There are two kinds of conventional pressures designed, one is 0.8MPa and the other is 1.6MPa. These two design pressures are based on usage needs.

When nitrogen is under pressure, the temperature reaches -196°C. It will become a dark blue liquid, which is liquid nitrogen. Liquid nitrogen can be stored under pressure or without pressure.

Of course, users can also measure the pressure for liquid nitrogen storage tanks according to their own needs. Just use our Cryogenic Pressure Transducer.

If you want to divide the level sensor into two categories. Then it can be divided into contact type and non-contact type liquid level sensor according to the measurement of whether it is released from the medium.

Extended reading: Non Contact Level Transmitters: Types & Industrial Applications

There are 7 main types of level transmitters that Sino-Instrument offers. Each type of transmitter works in a different way, and makes it useful for different types of processes.

Read more about: What is level transmitter working principle?

Sino-Inst is Manufacturer of Cryogenic Level Sensors for Liquid Nitrogen Tank Level Indicator. We supply more than 10 kinds of liquid nitrogen measure instruments.

Cryogenic Level Sensors are mainly used for level measurement of low temperature liquids.
It can measure even liquids such as Liquid Nitrogen, Liquid Oxygen, etc.

Cryogenic Level Sensors enable stable level measurement. This greatly meets the measurement needs of many applications. Can be used from small to large tanks.

Sino-Inst’s Cryogenic Level Sensors, made in China, Having good Quality, With better price. Our level measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

The entire team at Sino-Inst’s has received excellent training, so we can ensure that every client’s needs are met. For assistance with your product requirements, whether it’s a Cryogenic Level Sensor, flow sensor, or other device, give us a call.

Request a Quote

Please enable JavaScript in your browser to submit the form

Wu Peng, born in 1980, is a highly respected and accomplished male engineer with extensive experience in the field of automation. With over 20 years of industry experience, Wu has made significant contributions to both academia and engineering projects.

Throughout his career, Wu Peng has participated in numerous national and international engineering projects. Some of his most notable projects include the development of an intelligent control system for oil refineries, the design of a cutting-edge distributed control system for petrochemical plants, and the optimization of control algorithms for natural gas pipelines.

Collection of Industrial Insertion Flowmeter Types

Posted on September 13, 2022 by KimGuo11

What is an insertion flow meter?

Insertion flowmeter is a type of flowmeter in which the measuring probe is inserted into the pipe to measure the flow. This is a type of flow meter divided by structure. It includes various flow meters with different working principles. Insertion flowmeter plays an important role in the measurement of large-diameter water flow. Light weight, low pressure loss, easy installation and maintenance.

There are many types of insertion flowmeters that have been popularized and used. According to the working principle of the insertion flowmeter detection head, it can be divided into insertion turbine, insertion vortex, insertion electromagnetic, uniform velocity tube and thermal flowmeter.

RFQ Flow Meters

Featured Insertion Flowmeters for Sale

insertion flowmeter types

Insertion Magnetic Flow Meter, also called insertion electromagnetic flow meter, is an insertion type flow meter. Insertion magnetic flowmeter can be installed without stopping the flow. Suitable for large diameter DN300-3000.

Velocity measurement range: (0.1-10) m/s
Measuring pipe diameter: DN (100-3000) mm
Measurement accuracy: 1.5~2.5 class
Working pressure: <1.6MPa
Medium temperature: -20~150℃

Extended Reading: Special Magnetic Flowmeter Installation situation

Insertion Vortex Flow Meter is mainly used for flow measurement of gas, liquid, and steam fluid in large-diameter pipelines.

It can measure the volume flow and mass flow of steam, gas and liquid;
No mechanical moving parts, high measurement accuracy, compact structure and easy maintenance;
Small pressure loss, wide range; range up to 1:25;
Adopt interference elimination circuit and anti-vibration sensor head;
The use of disturbance elimination circuit and anti-vibration sensor head makes the instrument have certain anti-vibration performance;
The temperature of the measurable medium can reach +250℃.
The sensor can be disassembled and installed continuously, and the amplifier and the sensor can be separated (separation distance 15m);

The insertion target flowmeter is developed on the basis of the traditional target flowmeter.
It has the characteristics of flowmeter without moving parts such as orifice plate and vortex street. At the same time, it has high sensitivity, accuracy comparable to that of positive displacement flowmeters, and a wide range.

Wide range of applicable pipe diameters: Φ10~Φ2000 to larger;
Wide temperature range: -196°C ~ 500°C;
Applicable to high/low pressure conditions: 0~42MPa;
Applicable to various media: gas, liquid (including high viscosity liquid, slurry), steam;
It is suitable for medium with low flow velocity, and its measurable minimum flow velocity is 0.08m/s.

The SI-VL Verabar Flow Meter is designed with an aerodynamic engineering structure and is a sensor element. The VERIS Verabar Flow Meter is a Insertion flow meter. A Verabar tube sensor is inserted into the pipe. When the fluid flows through the sensor, a high-pressure distribution zone is created in the forward direction of the flow. And a low-pressure distribution zone is created in the rear. Verabar Flow Meter can be used to measure dry gas, humid gas, liquid or vapor, without being limited by dielectric constant.

The insertion turbine sensor is matched with the display instrument to form an insertion turbine flowmeter. The insertion turbine flowmeter can be widely used in large-diameter pipeline source water, circulating water, purified water, etc. to measure the volume instantaneous flow and total volume of liquids.

Insertion turbine flowmeter features:

The insertion turbine flowmeter has strong resistance to impurities. The tangential impeller can release the suspended debris in the fluid at any time when it rotates. so that it does not wrap around the blades of the tangential impeller;
The structure and principle of the sensor and display instrument are very simple and intuitive, and it is very easy for users to master their use and maintenance technology;
It has high anti-electromagnetic interference and anti-vibration capabilities, small pressure loss, wide flow range, and low lower limit flow rate. The impeller has anti-corrosion function;
The sensor can be installed in the open air, and the entire sensor can be used in water for a long time. Horizontal, vertical and inclined pipes can be used;
Sensor with shut-off valve. There is no need to cut off the current during installation and disassembly;

The Ultrasonic Insertion Flow Meter consists of a converter and a pair of insert sensors. The Insertion sensor consists of a positioning base, a ball valve, and a sensor core. Principle: When ultrasonic waves pass through the liquid, the liquid has a slight influence on the insertion time. The change of the insertion time is proportional to the liquid flow rate.

Annubar Flow Meter is a no-equal solution with a patented, averaging pitot tube that delivers superior measurement accuracy over a wide flow range. This flow meter can measure multiple variables and is engineered with an integrated thermowell for temperature measurement. Its patented T-shaped sensor is capable of obtaining measurements via a single pipe penetration while maintaining a small profile in the pipe to reduce permanent pressure loss and increase energy savings.

Insertion Thermal Mass Flow Meter can simultaneously display flow rate (flow), temperature. Low flow rates are responsive, and high flow rates can achieve good accuracy. Even at high temperature, a good constant temperature difference can be obtained, and the stability is good. There are a variety of installation options to choose from, with a measuring range up to 180Nm/s.

Measured medium: air, natural gas, biogas, coal gas, dry chlorine, oxygen, carbon monoxide combustion air, flue gas, flare gas, hydrogen, argon and other dry gases.

insertion flow meter wastewater

If an insertion flowmeter is to be selected for a wastewater pipeline, an insertion electromagnetic flowmeter must be the first choice.

The Insertion wastewater flowmeter can be widely used to measure the flow of conductive fluids in tap water, steel, petroleum, chemical industry, electric power, industry, water conservancy, water administration and water resources. It can also measure corrosive conductive liquids such as acids, alkalis, and salts.

The Insertion sewage flowmeter is mainly composed of a measuring head (or measuring tube), an excitation system, an insertion rod, a junction box, a mounting base, and a sealing and positioning mechanism.

Measuring head (or measuring tube): The measuring head (measuring tube) is located at the particle point of the measured flow velocity in the pipeline, and is used to detect the flow velocity at this point. A measuring head (or measuring tube) is a tip or conduit made of insulating material on which a pair of electrodes is mounted. Except for the electrode tip or the inner wall of the measuring tube, other parts are insulated from the fluid to be measured.

Excitation system: The function of the excitation system is to generate a working magnetic field. It consists of an excitation coil and an iron core. It is insulating sealed into the insertion rod.

Insert rod: Made of stainless steel material. The measuring head and the measuring tube are fixed in the insertion rod. The excitation lead and electrode lead are sealed with the measured medium and connected to the junction box through the insertion rod. A direction indicator is welded on the insertion rod to ensure that the working magnetic field, the flow rate and the electrode connection are perpendicular to each other during installation, which meets the requirements of Faraday’s law of electromagnetic induction.

Junction Box: The junction box is located on the top of the sensor. The terminals in the junction box connect the sensor and the converter to each other.

Mounting base: The mounting base is welded on the pipeline under test, used to connect with the mounting ball valve and insert the part of the sewage flowmeter sensor.

Sealing mechanism: It consists of a compression thread seat made of stainless steel, a compression nut, a rubber washer and a positioning screw. It is used to seal and insert the sewage sensor, so that it can avoid a certain working pressure.

insertion flow meter for air/compressed air

If you choose an insertion flowmeter for an air line, or a compressed air line. Then the insertion thermal mass flow meter can be said to be the first choice.

Because, the insertion thermal mass flow meter has obvious advantages:

Wide range ratio 1000:1; large diameter, low flow rate, negligible pressure loss;
Direct measurement of mass flow without temperature and pressure compensation;
Very sensitive measurement of low flow rates;
Easy to design and select, easy to install and use;
Suitable for all kinds of single or mixed gas flow measurement.

If you need to measure high temperature air, or high temperature compressed air. Then another type of flow meter may need to be selected. Such as high temperature Annubar flowmeter.

Frequently
Asked
Questions

The installation requirements of various insertion flowmeters vary. Here is a brief introduction to the standard installation of plug-in electromagnetic flowmeters:

The arrangement of instruments on the pipeline should be far away from the valve. Maintain a 10-diameter upstream intermediate pipe section and a 5-diameter downstream straight pipe section.
The on-site power supply needs to match the instrument power supply, generally a 24V rectifier. If there is no external power supply for the field measurement, an external power supply meter will be connected.
Pay attention to the flow direction of the measured liquid on the inner wall of the pipe. If the installation is reversed, the measured liquid will show a negative value.
The installation site should be cool and rain-proof. If it is often rained or immersed in water, the protection grade IP68 product should be selected.
The fluid flow in the pipeline should not be stopped if the process requires it. Media should not spill. A ball valve needs to be installed.

Different digital flow sensors include turbine, thermal mass, electromagnetic, ultrasonic, orifice plate, venturi. The different designs of the flowmeters have a variety of applications. With 4-20ma, RS485, or other output.

Then they all work differently. However, they can convert the flow signal into a digital display, or pulse, or 4-20mA signal.

Extended reading: Ultrasonic Flow Meters Types & Technical Guide

For different working principle, We offer different types of flow meters, like:

Differential Pressure Flow Meters
Orifice Plate
Venturi Tube
Flow Nozzles
The Sonic Nozzle – Critical (Choked) Flow Nozzle
Calorimetric Flowmeter
Ultrasonic Doppler Flowmeter
Positive Displacement Flowmeter
Variable Area Flowmeter or Rotameter
Velocity Flowmeters
Pitot Tubes
Electromagnetic Flowmeter
Turbine Flowmeter
Vortex Flow Meter
Thermal Flowmeter
Coriolis Flowmeter
Mass Flowmeters
Open Channel Flowmeters

Sino-Inst is Manufacturer of Insertion Flowmeters. We supply more than 20 kinds of Insertion Flow Meters. 40% insertion magnetic flowmeters, 30% insertion vortex flow meter and other types of flowmeters.

Insertion Flowmeters are mainly used for flow measurement of various liquids and gas.
It can measure even liquids such as water, seawater, oil, and slurry.

Insertion Flowmeters enable stable flow measurement without piping modifications. This greatly meets the measurement needs of many applications. Can be used from small to large tubes.

Sino-Inst’sInsertion Flowmeters, made in China, Having good Quality, With better price. Our flow measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

The entire team at Sino-Inst’s has received excellent training, so we can ensure that every client’s needs are met. For assistance with your product requirements, whether it’s an Insertion Flowmeter, level sensor, or other device, give us a call.

Request a Quote

Please enable JavaScript in your browser to submit the form

Crude Oil Flow Meter

Posted on September 12, 2022 by KimGuo11

Crude Oil Flow Meter refers to a type of flow meter that can accurately monitor and measure the flow of crude oil. Crude oil is an industrial raw material with complex physical and chemical properties. In the process of production, storage, transportation and trade, it is greatly affected by factors such as temperature, pressure and environment. Storage, transportation and handover not in accordance with standard specifications will lead to increased measurement errors and affect product quality.

Therefore, the flow measurement of crude oil has always been the focus and difficulty of the oil and gas extraction industry.

After years of service experience, Sino-Inst offers multiple crude oil flow meters. Including mass flowmeters, positive displacement flowmeters, turbine flowmeters, etc.

RFQ Flow Meters

Featured crude oil flow meters

**High Temperature Oval Gear Flow Meter – Heating oil**

types of crude oil flow meters

In terms of the medium to be measured, the crude oil containing impurities needs flow measurement, and the flow measurement of the working conditions with impurities itself is a big problem. Choosing the right crude oil flow meter is even harder.

Based on years of service experience, the following 7 type flowmeters are the types of flowmeters that we believe can effectively measure the flow of crude oil.

In order to realize the accurate measurement of crude oil production, real-time automatic measurement of incoming crude oil quality is the fundamental method.

The mass flow meter has high precision, easy to use and easy maintenance, and long service life. Crude oil production can be directly measured. It is supplemented by a computer real-time monitoring and measurement software system based on it. and utilize network resources. It can also realize remote real-time monitoring of the flowmeter.

The mass flow meter measures the crude oil quality, crude oil volume, water content, temperature and other data on the liquid pipeline in real time. It is displayed on the metering post through the on-site display instrument.

At the same time, the on-site display instrument transmits the relevant data signals to the on-site data storage and remote transmission equipment (industrial computer).

For the crude oil mass flowmeter used for single well measurement, due to the presence of some chemical substances in the measured medium, the flowmeter will cause scaling on the wall of the mass flowmeter measurement pipe after a period of operation.

The composition of scale is very complex, mainly composed of asphalt, wax, sulfide, carbide, etc.
The scale on the inner wall of the measuring tube of the flowmeter will affect the accuracy of mass flow and density measurement, thereby affecting the normal measurement performance of the mass flowmeter and causing a relatively large measurement error.

To ensure the normal use of the mass flowmeter, the flowmeter must be cleaned and descaled regularly. Then re-calibrate to determine the new configuration parameters of the instrument before it can be put into use again.

Extended Reading: Mechanical oil flow meter

It is well known that the oval gear flowmeter is especially suitable for the flow measurement of the medium with high viscosity such as heavy oil, polyvinyl alcohol, resin, etc. The oval gear flowmeter has high measurement accuracy. It is suitable for the measurement of high viscosity medium flow (generally the viscosity of the liquid to be measured is 2-3000Mpa.s).

But not suitable for fluids containing solid particles. If the measured liquid medium contains gas, it will also cause measurement errors.

Usually, the accuracy of the oval gear flowmeter can reach 0.5, which is a relatively accurate flow meter.

However, if the flow rate of the measured medium is too small, the influence of the leakage error of the oval gear flowmeter will be prominent. Sufficient measurement accuracy can no longer be guaranteed.

Extended Reading: Industrial petrol flow meters Types

The working principle of the dual rotor flowmeter is done in the metering chamber. It is directly meshed by a pair of special toothed helical rotors. No relative slippage.

Although the pressure of the liquid acting on the two rotors is different. However, a pair of synchronizing gears installed on the two rotors always maintains an appropriate gap between the two rotors, ensuring that the rotors can rotate smoothly and synchronously.

Several cavities with known volumes are formed between the rotor and the casing. Under the action of the measured medium, the micro-pressure difference between the inlet and outlet of the flowmeter drives the two helical rotors to rotate in opposite directions. The helical rotor can output 8 times the volume of the cavity per revolution.

Therefore, the number of revolutions of the rotor is proportional to the cumulative flow of the fluid. The rotational speed of the rotor is proportional to the instantaneous flow rate of the fluid. Therefore, the number of revolutions of the rotor can be transmitted to the counter through the transmission gear system to directly display the liquid flow.

At the same time, it can also be converted into an electrical pulse signal by adding an electromechanical conversion device. Then pass to the secondary instrument or computer for remote display and control.

The repeatability and stability of the dual-rotor flowmeter are in a linear state, which meets the requirements of crude oil export.

The dual-rotor flowmeter has been popularized and applied in various crude oil gathering and transportation stations and external transportation measurement rooms in oilfields. Undertook the measurement task of 4400t/d crude oil export, and its measurement data has been recognized by both sides of the trade.

Extended reading: Crude oil measurement, 80G radar level meter should be your first choice!

The target flowmeter adopts the latest force sensor as the measurement and sensitive transmission element. At the same time, the latest digital technology and microelectronic technology are applied. It is an intelligent flowmeter suitable for the measurement of fluids and gases with high viscosity, low Reynolds number and tiny particles.

The use of force sensors is the key to the true realization of high precision and high stability of this product.

The target flowmeter not only has the characteristics of traditional orifice plate, vortex flowmeter and other flowmeters without moving parts. At the same time, it has measurement accuracy comparable to that of positive displacement flowmeters. Coupled with its unique anti-interference, anti-impurity performance.

In addition to the target flowmeter can replace the conventional flowmeter and conventional fluid flow measurement. Especially in high viscosity, easy blocking, high temperature, high pressure, strong corrosion and other difficult flow measurement conditions have good application value.

At present, it has been widely used in flow measurement in various fields such as steel, oil, natural gas, electric power, papermaking, chemical industry, energy, food, environmental protection and so on.

Therefore, the target flowmeter is a good choice for measuring high viscosity crude oil.

As long as the Reynolds number fits within the measuring range of the target flowmeter, it can be measured. Viscosity changes do not need to be considered. In addition, it can be equipped with a temperature sensor for density correction, which can ensure good measurement accuracy.

Extended Reading: Petroleum Flow Meter

Turbine flowmeters can measure media such as special oils.

There are many varieties of oil, edible oil, peanut oil, diesel oil, gasoline, etc. are all oils. Turbine flowmeters measure the flow of liquids. However, it is not recommended to use it for measurement of too viscous liquids. Because the turbine flowmeter uses the principle of impeller rotation to measure the flow, and too viscous liquid will affect the rotation of the impeller.

Turbine flow meters can measure low temperature and non-viscous special oil. If the user’s working condition is measured on site, it is a special type of high temperature type oil. Nor can it be measured with a turbine flowmeter. The turbine flowmeter can only measure the working temperature when the ambient temperature on site is 120℃.

Therefore, the user chooses the turbine flowmeter to measure crude oil, and needs to choose according to the actual working conditions.

Magnetic Flow Meter is a flow meter that measures the flow of conductive fluids. Abbreviated as EMF, also called Electromagnetic flowmeters. It is a kind of Volumetric flow meter. A magnetic flow meter measures the velocity of conductive liquids moving through a pipe or conduit. In the wastewater treatment industry, Magnetic Flow Meter is the best flow meter choice.

The split-type electromagnetic flowmeter can also measure high-viscosity fluids. Based on the principle of electromagnetic flowmeter and other factors, this is theoretically true, but it also depends on the specific site.

In addition to measuring the flow of general conductive liquids, the split-type electromagnetic flowmeter can also measure liquid-solid two-phase flow, high-viscosity liquid flow and volume flow of salt, strong acid, and strong alkali liquids.

The differential pressure flow meter is measured by the working principle that there is a certain relationship between the pressure difference and the flow rate when the medium fluid flows through the throttling device. Differential pressure (DP) flow meters are the most widely used form of flow measurement products today. Including: integrated orifice flowmeter, average velocity tube flowmeter, venturi tube, wedge flowmeter, underwater flowmeter, orifice plate, orifice carrier assembly, nozzle flowmeter.

Differential pressure flowmeters always have unexpected advantages in measuring complex working conditions.

For example:
Wedge throttling device is a new type of throttling device developed by our company. , Its special structure, non-clogging, solid structure, long life, can be used to measure liquid, gas and steam.

It is especially suitable for flow measurement of fluids with low flow rate, high viscosity, dust or solid particles. Such as measuring crude oil, fuel oil, residual oil, coal tar, waste water, carbon black solution and other fluids.

Summary of Crude Oil Flow Measurement Options

Flowmeters are the most commonly used instruments in oil exploration enterprises. The selection of flowmeters used in many production sites in oil fields is not reasonable, and some have installation errors, resulting in excessive measurement errors, and some cannot meet the needs of production or crude oil transfer measurement.

Many forms of flowmeters can measure crude oil, but when choosing a model based on experience and simply considering the purchase cost, you may lose the opportunity to choose the most suitable meter.

For example, the flow range of the instrument does not match the actual flow, and the instrument with high precision is selected for places with low measurement requirements.

It can be seen that the correct selection and use of flow meters is not an easy task. To choose a crude oil flowmeter correctly and efficiently. The following five factors must be considered, namely: performance requirements, physical properties of crude oil, installation requirements, environmental conditions and costs.

Read more about: Flow Meter Selection Guide

When selecting a flowmeter, the performance requirements to consider include: instantaneous flow, cumulative flow, degree, repeatability, linearity, flow range and range, pressure loss, output signal characteristics and response time.

Different measurement purposes have different options in terms of flowmeter performance. Such as crude oil trade settlement measurement requirements are relatively high.

Continuous measurement process control usually requires good reliability and repeatability. Sometimes a wide range of degrees is also required, and the requirements for measurement degrees should be placed in a secondary position.

The oilfield production site does not require the flowmeter to have too high accuracy, but it has good adaptability to the physical properties and working conditions of crude oil.

The operation of the crude oil flowmeter is affected by factors such as crude oil temperature, oil delivery pressure, crude oil density, crude oil viscosity, and flow rate.

The physical properties of crude oil will change to some extent with the changes of temperature and pressure.

When crude oil is measured by a flow meter, the volume of crude oil will be affected by changes in temperature, pressure, viscosity and other factors.

Among them, temperature is one of the most influential parameters in flow meter measurement. Changes in temperature can cause changes in a series of parameters, which change the volume, density, viscosity of the crude oil and the gap between the flowmeter housing and internal components, thus resulting in changes in leakage flow.

If the temperature is lowered, the paraffin and coke in the crude oil adhere to the inner wall of the shell and parts. This changes the volume of the metering chamber of the flowmeter. It directly affects the measurement accuracy of the flowmeter.

Flow meters of different principles have very different installation requirements. For example, differential pressure and turbine flowmeters require a long upstream straight pipe section, and some flowmeters do not have this requirement or have lower requirements. Some flowmeters need to consider the installation location and medium flow direction, maintenance space, installation direction, etc.

The measurement performance of the flowmeter is greatly affected by the installation conditions, and the reason for the large error of the flowmeter. Part of it is caused by poor installation.

Factors to be considered in the installation are: the installation direction of the flowmeter, the flow direction of the crude oil, the upstream and downstream straight pipe sections, the valve position, vibration, electromagnetic interference and maintenance space.

The ambient conditions of the meter and its expected changes, including ambient temperature, humidity, safety, and electrical interference, should be considered in the flowmeter selection process. The electronics of the meter and some of the meter’s flow sensing portion are affected by changes in ambient temperature.

For example, the size of the flow meter housing changes, and the heat transfer through the meter housing changes the density and viscosity of the fluid. When affecting the display meter electronics, it will degrade measurement performance. Sometimes the conversion display part and the flow sensor are installed in different places to ensure that the electronic components are not affected by temperature.

High humidity will accelerate atmospheric corrosion and electrolytic corrosion and reduce electrical insulation, and low humidity is prone to static electricity. These can have an effect on the circuit part of the flowmeter and sometimes even cause a malfunction.

In terms of economy, it is not comprehensive to consider only the purchase cost of the instrument, and other costs should also be considered. Such as accessories purchase costs, installation costs, maintenance and flow meter verification costs, operating costs and spare parts costs. Trade settlement measurement should also compare the economic losses caused by measurement errors.

The operating cost of the flowmeter is mainly the energy consumption during operation. Some flowmeters are powered by dry batteries, and the cost of battery consumption is also considerable. Pumping costs are a hidden cost that is often overlooked.

The maintenance cost is the cost required to maintain the normal operation of the measurement system after the instrument is installed and put into use, mainly including maintenance labor and spare parts. Instruments with moving parts generally require more maintenance work, such as regular replacement of wear-resistant bearings, shafts, rotors, transmission gears, etc.

The selection of crude oil flowmeter should comprehensively consider the five factors of instrument performance, fluid characteristics, installation conditions, environmental conditions and economy.

Encounter the phenomenon that the physical properties of crude oil, especially the viscosity-temperature characteristics, are not very clear. Special units should be invited to do a complete set of crude oil tests and make a physical property report.

Consult with the flowmeter manufacturer or technical department about the adaptability of various flowmeters and the influence of physical property changes on the performance of the flowmeter. Choose a flowmeter that meets your needs.

flow measurement in oil and gas industry

Every day, a large amount of oil and gas are transported back and forth, refined, and then transported, as well as custody transfer. Difficult oil and gas flow measurement challenges such as corrosive media and harsh environments are our daily work. This requires mature and safe technology. Through instrument measurement and display monitoring, safe and reliable operation can be achieved.

Many types of flow meters are used to measure oil and gas flow. Each type has its advantages and disadvantages.

Frequently
Asked
Questions

Measuring oil flow is to measure the volume or mass flow of oil. According to the actual demand, and the actual parameters of the oil, the appropriate oil flow meter can be selected.

Extended reading: What Is Hydraulic Flow Meter?

Industrial oil flow meters measure the volume or mass of oil. Can realize the mutual conversion of volume and mass.

The main industrial oils are hydraulic oil. Gear Oil. Turbine oil. Compressor oil. Refrigeration oil. Transformer oil. Cylinder oil, heat treatment oil, heat transfer oil, etc. Of course, edible oil can also be produced in the industry. In addition, there are greases with lubricating oil as base oil and thickening agent.

Therefore, whether it is a company that uses, trades, or produces oil, it needs to accurately measure the oil flow.

There are many common oil flow meters, such as turbine flow meters, positive displacement flow meters, gear flow meters, mass flow meters, etc.

In the oil and gas industry, monitoring is required most of the time during transportation and processing. Including pressure, temperature, liquid level, flow, viscosity and more. And to achieve these functions are process meters.

Therefore, in the oil and gas industry, many meters are used. For example: thermometers, pressure gauges, flow meters, etc.

If the flowmeter is divided into 5 categories. Then the five commonly used flowmeters are:

Electromagnetic flowmeter
Differential pressure flowmeter
Turbine flowmeter
Ultrasonic flowmeter
Volumetric flowmeter (PD)

Then they all work differently. However, they can convert the flow signal into a digital display, or pulse, or 4-20mA signal.

Extended reading: Ultrasonic Flow Meters Types & Technical Guide

Sino-Inst is Manufacturer of Crude Oil Flow Meters. We supply more than 20 kinds of Crude Oil Flow Meters. 40% mass flowmeters,30% oval gear flow meters and other types of flowmeters.

Crude Oil Flow Meters are mainly used for flow measurement of high viscosity crude oil flow.

Crude Oil Flow Meters enable stable flow measurement without piping modifications. This greatly meets the measurement needs of many applications. Can be used from small to large tubes.

Sino-Inst’s Crude Oil Flow Meters, made in China, Having good Quality, With better price. Our flow measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

The entire team at Sino-Inst’s has received excellent training, so we can ensure that every client’s needs are met. For assistance with your product requirements, whether it’s a Crude Oil Flow Meter, level sensor, or other device, give us a call.

Request a Quote

Please enable JavaScript in your browser to submit the form

Browse all pressure transmitters | How pressure transmitters work | Calibration guide

Pressure Transducer Wiring Diagram: 2-Wire, 3-Wire & 4-Wire Guide

Posted on September 6, 2022 by KimGuo11

Updated April 2026 — By Sino-Inst Engineering Team

Wiring a pressure transducer correctly is the difference between a clean 4–20 mA signal and hours of troubleshooting. The three wiring configurations — 2-wire, 3-wire, and 4-wire — each have different power supply requirements, signal routing, and use cases.

This guide provides wiring diagrams for all three types, explains the electrical differences, and covers the most common wiring mistakes.

2-Wire vs 3-Wire vs 4-Wire: Quick Comparison
2-Wire Pressure Transducer Wiring Diagram
3-Wire Pressure Transducer Wiring Diagram
4-Wire Pressure Transducer Wiring Diagram
Common Wiring Mistakes
Featured Pressure Transmitters
FAQ
Request a Quote

2-Wire vs 3-Wire vs 4-Wire: Quick Comparison

Feature	2-Wire	3-Wire	4-Wire
Cables required	2	3	4
Power & signal	Share same 2 wires	Shared ground, separate signal	Fully separate
Common output	4–20 mA	0–10 V or 4–20 mA	4–20 mA, 0–10 V, 0–5 V
Power supply	12–36 VDC (loop)	12–36 VDC	12–36 VDC or 220 VAC
Max cable length	1–2 km	500 m	500 m (voltage) / 1–2 km (current)
Cost	Lowest	Medium	Highest
Best for	Process control, long runs	Test/lab, moderate distance	High-accuracy, multi-function

2-Wire Pressure Transducer Wiring Diagram

A 2-wire transmitter is loop-powered. The power supply and the 4–20 mA signal share the same two wires. At zero pressure, the transmitter draws 4 mA. At full scale, it draws 20 mA. The PLC analog input reads this current to determine the pressure.

Wiring steps:

Connect the positive (+) terminal of the 24 VDC power supply to the positive (+) terminal of the transmitter.
Connect the negative (−) terminal of the transmitter to the positive (+) input of the PLC analog module (or across a 250 Ω resistor for voltage conversion).
Connect the negative (−) terminal of the PLC analog module back to the negative (−) terminal of the 24 VDC power supply.

The 2-wire configuration is the industry standard for process control. It uses less cable, is immune to lead resistance errors (current signals are not affected by wire length), and supports HART communication on the same two wires. Over 80% of industrial pressure transmitters use 2-wire 4–20 mA connections.

3-Wire Pressure Transducer Wiring Diagram

A 3-wire transmitter has a dedicated power positive wire, a signal output wire, and a shared ground (common) wire. The power supply and signal output share the negative/ground connection.

Wiring steps:

Connect V+ (power positive) to the positive terminal of the 24 VDC power supply.
Connect Signal Out to the positive input of your PLC analog module or display instrument.
Connect GND (common) to both the negative terminal of the power supply and the negative terminal of the PLC input.

The 3-wire configuration is common in voltage-output transmitters (0–5 V, 0–10 V). The separate signal wire avoids the voltage drop issue that affects 2-wire voltage transmitters over long cable runs. However, for distances over 500 m, a 4–20 mA current output is still preferred.

4-Wire Pressure Transducer Wiring Diagram

A 4-wire transmitter has completely separate power and signal circuits — two wires for power, two wires for signal. This isolation between power and measurement eliminates ground loops and allows both current and voltage output options.

Wiring steps:

Connect Power + to the positive terminal of the power supply (24 VDC or 220 VAC depending on model).
Connect Power − to the negative terminal of the power supply.
Connect Signal + (current or voltage output) to the positive input of the PLC analog module.
Connect Signal − to the negative input of the PLC analog module.

The 4-wire configuration is used in high-performance transmitters that need more power than a 2-wire loop can provide (the 4 mA minimum in a 2-wire system limits the available power to roughly 36 mW at 24 V). Transmitters with LCD displays, HART modems, or multiple outputs often require 4-wire power. Some 4-wire models accept 220 VAC directly.

Common Wiring Mistakes

Reversed polarity. Connecting + and − backwards. Most modern transmitters have reverse polarity protection, but some older models can be damaged. Always check terminal markings before applying power.

Wrong supply voltage. Applying 220 VAC to a 24 VDC transmitter destroys it instantly. Confirm the rated voltage on the nameplate.

Load resistance too high. A 2-wire 4–20 mA transmitter needs enough voltage to drive the current through the total loop resistance. If your PLC input impedance plus cable resistance exceeds the transmitter’s maximum load, the signal clips at the top end. Check the specification: most 24 VDC transmitters support up to 500–750 Ω total loop resistance.

Ground loops. Connecting the signal ground to the power ground at multiple points creates a ground loop. This adds 50/60 Hz noise to the signal. Use a single grounding point, or use a 2-wire 4–20 mA transmitter (current loops are inherently immune to ground loops).

Mixing up TEST and OUT terminals. Some transmitters have both OUT (operating output) and TEST (factory calibration) terminals. Only connect to the OUT terminals for normal operation.

Featured Pressure Transmitters from Sino-Inst

2-Wire 4–20 mA Transmitter

Loop-powered | ±0.25% FS
24 VDC | SS316L | HART option

Request Quote

4-Wire DP Transmitter

Separate power/signal | ±0.075% FS
HART/Modbus | LCD display

Request Quote

Explosion-Proof Transmitter

ATEX/IECEx | Intrinsically safe
2-wire or 4-wire | IP67

Request Quote

Pressure Transducer Wiring FAQ

What happens if I wire a 2-wire transmitter with wrong polarity?

Reverse polarity on a 2-wire transmitter blocks current flow completely. The loop reads 0 mA, and the PLC/DCS shows an under-range fault. Most modern transmitters have built-in reverse-polarity protection — the device won’t be damaged, but it won’t output a signal until you swap the wires. Always check with a multimeter before powering on.

Can I use a 4-wire transmitter in a 2-wire loop?

No. A 4-wire transmitter needs a separate power supply and has dedicated signal output terminals. You cannot wire it into a standard 2-wire 4–20 mA loop. If your system only supports 2-wire loops, you need a 2-wire transmitter or a signal isolator to convert the 4-wire output.

How long can I run 4–20 mA signal cable?

With standard 18 AWG twisted-pair cable, a 4–20 mA loop typically runs up to 1,500 meters (about 5,000 feet). The limiting factor is total loop resistance — keep it under what the transmitter can drive. For a 24 VDC supply with a 250 Ω sense resistor, a typical transmitter handles around 600 Ω total loop resistance. Longer runs need thicker cable or a higher supply voltage.

Why does my pressure reading drift after wiring?

Common causes: loose terminal connections causing intermittent contact, incorrect grounding creating ground loops, or EMI pickup from running signal wires alongside power cables. Check all connections are tight, verify single-point grounding, and use shielded cable with the shield grounded at one end only.

Do I need shielded cable for pressure transducer wiring?

For 4–20 mA loops in industrial environments — yes. Shielded twisted-pair cable reduces electromagnetic interference from VFDs, motors, and switchgear. Ground the shield at the control room end only. For short runs in electrically quiet environments, unshielded cable works, but shielded is always the safer choice.

What is the minimum supply voltage for a 2-wire transmitter?

Most 2-wire transmitters need 12–36 VDC, but check the specific model’s datasheet. The actual minimum depends on total loop resistance. A rough formula: V_min = 12V + (0.02A × R_loop). With a 250 Ω load resistor and 50 Ω cable resistance, you need at least 18 VDC. A 24 VDC supply handles most installations.

Written by the Sino-Inst Engineering Team — with over 20 years of experience in industrial pressure measurement, installation, and commissioning across oil & gas, water treatment, HVAC, and chemical processing plants worldwide.

Request a Quote or Technical Support

Need help selecting the right pressure transducer for your wiring configuration? Our engineers can recommend the best signal output type — 2-wire, 3-wire, or 4-wire — based on your system requirements.

Request a Quote

Please enable JavaScript in your browser to submit the form

Non Contact Level Transmitters: Types & Industrial Applications

Posted on September 5, 2022 by KimGuo11

Non Contact Level Transmitters are now more and more widely used in industrial level monitoring. We most often provide customers with non-contact radar level transmitters and ultrasonic level meters. Both liquids and solids can be measured with Non Contact Level Transmitters. There is no need to dig the level probe deep into the measured medium. The sensitive elements measured by Non Contact Level Transmitters are not in contact with the liquid being measured. It can be used in special occasions that contact measuring instruments cannot meet. Such as the medium with high viscosity, strong corrosiveness, strong pollution and easy crystallization.

RFQ Level Meters

Featured Non Contact Level Transmitters for Sale

**SI-FMF11 FMCW Radar Level Transmitter 120GHz**

**SIRD-905 Horn Antenna Radar Tank Level Sensor**

**SIRD-802 Radar Level Sensor for Corrosive Liquids**

**SIRD-806 Radar High Temperature Level Sensor**

**ULT-100A Ultrasonic Level Transducer**

**ULT-200A Ultrasonic fuel tank level sensor**

**HS-2000 Ultrasonic Tank Level Sensor-External Mounted**

Non Contact Level Transmitters Types

In order to choose the most suitable level sensor, we not only need to know the properties and state of the liquid being measured. It is also necessary to understand the advantages and disadvantages of different level sensors. in order to select the most suitable sensor. Next, let’s briefly introduce the common non-contact liquid level measurement methods and their characteristics.

Common non-contact measurement methods mainly include ray level meter, ultrasonic level meter, laser ranging sensor and radar level meter.

The rays emitted by nuclear radiation (such as gamma rays, etc.) have strong penetrating ability. And through the medium of different thickness has different attenuation characteristics. The nuclear radiation level meter uses this principle to measure the liquid level.

The nuclear radiation source of the nuclear radiation level gauge is installed outside the oil tank with a point or narrow structure. The elongated nuclear radiation source detection element is also installed outside the oil tank. It can realize the detection of dynamic change of liquid level.

In addition to measuring with nuclear radiation rays, neutron rays can also be used to measure liquid level.

The ray level meter is very convenient to install and has high measurement accuracy.

Because it does not have any parts in direct contact with the measured object. It is especially suitable for measurement problems that cannot be solved by traditional measuring instruments.

Extended reading: liquid nitrogen level measurement

The propagation speed of ultrasonic waves in the same medium is relatively constant. Reflection occurs when it encounters the surface of the object being measured. Based on this principle, an ultrasonic level meter was developed. It calculates the liquid level height by detecting the time difference between ultrasonic transmission and reflection. Therefore, it is easily affected by the energy loss of ultrasonic propagation.

The ultrasonic level meter has the characteristics of easy installation and high flexibility. However, when used in environments containing steam and powder layers, the detection distance will be significantly shortened. Not recommended for use in absorbing environments such as foam.

In addition, the accuracy of the ultrasonic level meter is slightly lower than that of the radar level meter, and the price is moderate.

Extended Reading: How to Measure Volume of Liquid

Its measurement principle is similar to that of an ultrasonic level meter. Just use light waves instead of ultrasound. The emission sensor emits laser light and irradiates it to the liquid surface to be measured. Reflection occurs at the liquid surface, and the receiving sensor receives the reflected light. Convert the time from transmit to receive to level.

The beam of a laser is narrow, so its spot is small and concentrated. Therefore, it is very suitable for containers with narrow openings and measurement objects with high temperature and high viscosity.

Laser ranging sensor level meters are easy to install, calibrate, and flexible. The price is relatively affordable, and it can be used for continuous or limit alarms of bulk materials or liquid levels.

If it is a transparent liquid and oil, it is necessary to add a reflective buoy on the liquid surface before it can be measured. Not suitable for use in foam or steam environment (cannot penetrate foam or easily disturbed by steam), fluctuating liquid (easy to cause malfunction), vibration environment, etc.

Radar level meters usually use the principle of frequency modulation radar. Utilize synchronous FM pulse technology. Mount the microwave transmitter and receiver on the top of the tank. A frequency-modulated microwave signal is emitted to the liquid surface.

When the echo signal is received, due to the delay of the round-trip propagation time. The transmission frequency has changed. The two signals are mixed and processed, and the difference frequency of the obtained signal is proportional to the distance between the tank top and the liquid surface.

The radar level meter has a large measurement range and is not affected by harsh weather environments. And easy to install, low maintenance and other advantages,

Especially suitable for high viscosity or high pollution products, such as asphalt. Radar level meters provide high measurement accuracy and do not require regular maintenance and recalibration. But the installation is more complicated and the price is relatively high.

Extended reading: Oil-water interface measurement-Magtech magnetic level indicator

Radar Type Level Transmitter Working Principle

Radar Level Measurement and guide wave radar level measurement Image source: https://instrumentationtools.com/radar-level-measurement/

Very short microwave pulses with very low energy are transmitted and received through the antenna system. The radar wave runs at the speed of light. The operating time can be converted into level signals by electronic components. A special time extension method can ensure stable and accurate measurement in a very short time.

Electromagnetic waves propagate in the air at the speed of light. The distance between the radar level gauge and the surface of the material can be expressed by the following formula: 　　

D = (1/2)*CT

In the formula:

D ———the distance between the radar level gauge and the surface of the material; 　　

C ———Speed of light 　　

T ———Pulse time.

Then the liquid level is: 　　L = E-D

In the formula:

L — liquid level; 　　

E ———The total height of the tank; 　　

D ———Air height.

Even in the presence of false reflections, the new micro-processing technology and the unique ECHOFOX- software can accurately analyze the level echo. By inputting the size of the container, the distance value can be converted into a signal proportional to the level. The instrument can be debugged with empty positions.

Extended reading: Amazing Solutions for Continuous Liquid Level Measurement

Ultrasonic Level Transmitter Working Principle

The working principle of the ultrasonic level sensor is:

Ultrasonic transducer (probe) emits high-frequency pulse sound waves, and the surface of the measured level (material) is reflected back. The reflected echo is received by the transducer and converted into an electrical signal. The propagation time of the sound wave is proportional to the distance from the sound wave to the surface of the object.

The relationship between the sound wave transmission distance S and the sound speed C and the sound transmission time T can be expressed by the formula: S=C×T/2.

Image Source： https://www.coulton.com/beginners_guide_to_ultrasonic_level_transmitters.html

The probe part emits ultrasonic waves, which are then reflected by the liquid surface. The probe part is received again. The distance from the probe to the liquid (object) surface is proportional to the elapsed time of the ultrasonic wave:
hb = CT2
Distance [m] = time × speed of sound/2 [m]
The temperature compensation formula of sound velocity:
Ambient sound velocity = 331.5 + 0.6 × temperature

Non Contact Level Transmitters Industrial Applications

Sino-Inst’s Non Contact Level Transmitters, whether ultrasonic level meter or radar level meter, are widely used in various industries.

Highly toxic medium
Bromine
liquid chlorine
Liquid ammonia
dimethyl ether

Oil, flammable and explosive media
gasoline and diesel
crude
heavy oil

Volatile media in pressure vessels
liquefied gas
C4
acrylic
liquified natural gas

Corrosive media
Anhydrous hydrogen fluoride
Bromine

Other media
methanol
fuel styrene
wax oil
Acetylene

Chlor-alkali
Storage and transportation
petrochemical
Coal chemical industry
oil refining
Fluorine chemical
fertilizer
pesticide
electricity
liquid storage
other industry

Extended reading: Oil-water interface measurement-Magtech magnetic level indicator

Frequently
Asked
Questions

Non contact level sensor refers to a type of level meters that the liquid level sensor does not need to contact the measured medium during measurement.
Common Non contact level sensors include ultrasonic level meters and radar level meters.

Extended Reading: Silo/Bin material level measurement system

There are 7 main types of level transmitters that Sino-Instrument offers. Each type of transmitter works in a different way, and makes it useful for different types of processes.

For more about: Types of Level Transmitters

Non contact water level sensor refers to the radar water level sensor. Radar Water Level Sensor is suitable for water level monitoring of lakes, rivers, reservoirs, open channels, and tidal water levels.

Radar Non-Contact Water Level Sensor adopts a non-contact measurement method and does not touch the water body. It is not affected by water quality, sediment and floating objects. The RS-485/RS-232/4-20mA interface can realize data long-distance wired transmission or docking with SCADA hydrological telemetry system. The measuring distance can be up to 70 meters.

Extended Reading: Dielectric constant for radar level transmitter

The non-contact liquid level meter has its unique advantages. There is no need to install the sensor on the tank wall during installation, and the instrument does not contact the liquid medium in the container. It effectively solves the technical problem of measuring liquid level under special harsh and harsh conditions such as strong corrosion, high toxicity, high pressure, flammability and explosion, high purity, and no bacterial infection.

Extended reading: Capacitance level sensor advantages and disadvantages

Read more about: River Water Level Monitoring System

Sino-Inst is Manufacturer of Non Contact Level Transmitters. We supply more than 20 kinds of Non Contact Level Transmitters. 40% ultrasonic level meters, 40% radar level transmitters and 20% other types of flowmeters.

Non Contact Level Transmitters are mainly used for level measurement of various liquids and solid particles.
It can measure even liquids such as water, seawater, oil, and slurry.

Non Contact Level Transmitters enable stable level measurement without tank modifications. This greatly meets the measurement needs of many applications. Can be used from small to large tanks.

Sino-Inst’s Non Contact Level Transmitters, made in China, Having good Quality, With better price. Our level measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

The entire team at Sino-Inst’s has received excellent training, so we can ensure that every client’s needs are met. For assistance with your product requirements, whether it’s a Non Contact Level Transmitters, flow sensor, or other device, give us a call.

Request a Quote

Please enable JavaScript in your browser to submit the form

High Accuracy Pressure Transducers

Posted on August 21, 2022 by KimGuo11

High Accuracy Pressure Transducers are also called high precision pressure transducers or high accuracy pressure sensors. Sino-Inst manufactures various types of High Accuracy Pressure Transducers.

From the perspective of accuracy, the accuracy of conventional pressure transmitters is 0.5%. Therefore, pressure transmitters can be divided into high-precision pressure transmitters (0.1% or 0.2% or 0.075%) and general pressure transmitters ( 0.5%).

High Accuracy Pressure Transducers support mV/V, V, mA and digital outputs. Ideal for applications requiring very high precision measurements such as oil, gas and geothermal energy exploration.

Checklist: Pressure Transmitter 4-20mA Common Faults and Error

Featured High Accuracy Pressure Transducers for Sale

**SI-703 Flush diaphragm pressure sensor**

**SI-706 Combined Pressure and Temperature Sensor-Dual function**

**Flange Mounted Differential Pressure Transmitter**

**Differential pressure(DP) level transmitter**

When ordering a pressure transmitter, you can often be asked what accuracy pressure transmitter you need. Then our sales engineer will tell you that we have 0.5% accuracy and 0.1% accuracy. Even higher precision ones can be customized.

Also, different accuracy may affect the price of the pressure transmitter. So what is the accuracy of the pressure transmitter? Do we need to blindly pursue higher-precision pressure transmitters?

Extended Reading: 4-20ma pressure transducer wiring diagram

What is the accuracy of a pressure transmitter?

The accuracy of the pressure transmitter is the same as that of all measurement and display instruments, and it is an indicator of the reliability of the measured value of the instrument.

The instrument has a maximum allowable error (deviation), and the probability of more than 98% of the results obtained from N times of measurements on the same measured value does not exceed this range.

Maximum allowable error / measuring range * % = meter accuracy

For a pressure transmitter with an accuracy of class 0.1,

Output allowable error = output range * instrument accuracy% = 16 * 0.001 = 0.016 (mA)

That is, the maximum possible error when this meter is measured is plus or minus 0.065mA.

Extended reading: Pressure Sensor Applications-Featured Industry Applications

A pressure transmitter in the general sense is mainly composed of a load cell sensor (also called a pressure sensor), a measurement circuit and a process connection. It can convert physical pressure parameters such as gas and liquid sensed by the load cell sensor into standard electrical signals (such as 4~20mADC, etc.) to supply secondary instruments such as indicating alarms, recorders, and regulators for measurement and indication. and process regulation.

The pressure transmitter is an instrument that accepts pressure variables and converts the pressure changes into standard output signals in a certain proportion after sensing and conversion. The output signal of the transmitter is transmitted to the central control room for pressure indication, recording or control.

Usually, when considering the overall accuracy of the pressure transmitter, the factors that affect the accuracy of the pressure transmitter generally need to be considered.

According to the experience of Sino-Inst, we believe that everyone should choose the tolerance of the pressure transmitter according to the requirements of the industrial process. Instead of selecting according to the pressure transmitter indicators installed in the field.

Extended reading: Water Pressure Sensors for Measurement of Water Pressure

Factors affecting the overall accuracy of pressure transmitters

In the pressure transmitter manual or website, there is usually a separate and limited description of the accuracy. It might be called “reference precision” or something similar. But this only includes some of the factors that affect accuracy, not all. For example it only includes nonlinearity, hysteresis and repeatability.

This “best accuracy” does not take into account all factors that affect accuracy in practice (installation location, ambient temperature, etc.).

Therefore, do not think that the pressure transmitter is installed in an industrial process. This precision can be achieved in practical applications.

For a high-accuracy pressure transmitter, the “best accuracy” might be 0.04% or 0.025% of the pressure span.

The best (reference) accuracy is generally only for a few pressure ranges, not the full pressure range. And, it may vary with different pressure types. That is, the absolute range is not necessarily equal to the full range.

Accuracy specifications may be doubled or tripled for different ranges.

So make sure you know the accuracy for the pressure range/model you are using.

Extended Reading: strain gauge pressure transducer

The HART intelligent pressure transmitter can rescale its accuracy range in any ratio. Pressure transmitters can typically be scaled by 100:1 or higher adjustment specific gravity. Accuracy specifications typically give either full scale or a limited turndown ratio.

If the HART smart pressure transmitter is re-ranged to less than full scale, the accuracy specification will usually be degraded.

Therefore, if you re-range the pressure transmitter to less than the maximum range, you need to confirm how much accuracy error is incurred.

Most pressure transmitters in use are subject to changing environmental conditions. Likewise, the temperature of the pressure medium may vary considerably during use.

Like most measuring devices, pressure transmitters usually have some kind of temperature coefficient, a factor that affects accuracy depending on the ambient temperature. This temperature-dependent property seems to be commonly specified in an incomprehensible expression.

But try to understand this, and if you can’t figure this out, ask the pressure transmitter manufacturer.

It may vary from 0.01% to 0.5% of span for different pressure transmitters.

The worst-case pressure model indicated temperature effects may exceed 1% of range.

You should take this into account if the temperature varies widely during use.

The differential pressure transmitter can be used under the condition of pipeline static pressure. This means that both inputs have a certain pressure, and the differential pressure transmitter measures the difference between the two inputs. It is different from a transmitter that measures pressure under atmospheric conditions or a transmitter that measures absolute pressure under complete vacuum conditions.

An ideal differential pressure transmitter can only measure the difference between the inputs. But static line pressure actually has some effect on the output. If both inputs are at atmospheric pressure, the differential pressure is naturally zero.

Likewise, if the same pressure (say 50 bar/psi) is applied to both inputs, the differential pressure is still zero.

In fact, static pressure will have a certain effect on the output of the transmitter.

Therefore, when the static pressure changes, the differential pressure transmitter output also changes slightly.

Static pressure effects typically vary from 0.025% to 0.4% of span, depending on the differential pressure transmitter model.

Static pressure generally mainly changes the zero position of the differential pressure transmitter without significantly affecting the measurement full scale. Therefore, in the calibration process, after applying the same pressure (high pressure or low pressure) to both input terminals, observe the change value of the zero position of the differential pressure transmitter to verify this effect.

Line pressure may also have an effect on the measuring range of the differential pressure transmitter, which increases the difficulty of operation and calibration. It needs to be calibrated using a differential pressure standard.

More About: Differences! Static pressure vs dynamic pressure vs total pressure.

All measuring equipment will gradually lose accuracy over time. Some increase, some decrease. The same goes for pressure transmitters. Some pressure transmitters have a one-year stability guarantee, and some are even 5 or 10 years or more.

For example, a pressure transmitter with a reference accuracy of 0.04% of span can have an annual stability of 0.2% of span. For some other models, 0.2% span stability can be effective for 5 or even 10 years.

Depending on how often the pressure transmitter is recalibrated, you should consider long-term stability effects, as the pressure transmitter may drift significantly before the next recalibration (and possibly trim).

The installation location often affects the accuracy of the pressure transmitter. Most pressure transmitters will specify a mounting location.

Changing the installation orientation will generally cause the zero position of the pressure transmitter to change, but will not affect the accuracy of the full scale measurement. In fact, the mounting orientation of the pressure transmitter does not change during normal use. The location of the pressure transmitter should be considered when the pressure transmitter is calibrated in the workshop and installed in an industrial process, or when the pressure transmitter is removed from an industrial process for recalibration.

Of course, if the transmitter is a remote differential pressure type, the installation position of the capillary will have a great influence on the zero value. Again, this isn’t something that doesn’t change during normal use. Calibration may be affected if the remote differential pressure transmitter is removed from the installation location.

Many pressure transmitters specify vibration effects. Of course, this only needs to be considered when the pressure transmitter is installed in a vibrating location. The effect of vibration on accuracy is usually small, eg “less than 0.1% of span”.

The two-wire pressure transmitter will not work when the external power supply is not connected. The common power supply is 24VDC power supply. Pressure transmitters can usually operate over a wide supply voltage range, even down to 10 VDC. However, when the supply voltage changes during operation, it has little effect on the accuracy of the pressure transmitter.

For example, it can be specified as “every 1V of power supply voltage will produce less than 0.01% change of measurement range”. In fact, when the power supply can be used normally, there is generally no problem.

The index parameters of the overall accuracy of some pressure transmitters contain several common factors that affect the accuracy. These include the “reference accuracy” mentioned above and the effect of ambient temperature and static/line pressure. This overall accuracy is easier to grasp because it is closer to what a pressure transmitter can achieve.

For example, an “overall accuracy” specification might be 0.14% of span, while the reference value is 0.04%. Therefore, once temperature and line pressure effects are included, the reference accuracy is multiplied by 3-4.

Another example is that there is a 0.075% range reference accuracy, when the temperature effect is considered, the accuracy is reduced to 0.2% of the range, and when the static pressure effect is further considered, the accuracy is reduced to 0.3% of the range.

If the index parameters of the overall accuracy of the pressure transmitter are clear. This will help you gain an in-depth understanding of the type of accuracy that can be achieved in practice. Even these overall accuracies are often missing some of the factors listed in this paper.

When using a pressure transmitter to measure pressure, there is a risk that the membrane of the transmitter will be contaminated by the pressure medium or some dirt. Such contamination can seriously affect the accuracy of the pressure transmitter.

Of course, this is not something that is explicitly stated. But it can also be considered a big risk in normal use, especially if you decide to recalibrate with a long period of time (eg, years). Therefore, in addition to the long-term drift indicator parameters of the pressure transmitter, this needs to be considered in the risk analysis.

If the pressure transmitter gets very dirty and starts to experience significant measurement errors, you will generally find this in the measurement results.

However, if it is only a small error, it is difficult to notice it in normal use.

Read more about: What Are 0-10V Pressure Transducers?

pressure transducer 4-20mA

Many friends have some misunderstandings about this issue, and feel that 4-20mAdc is more troublesome to calculate. So why use 4-20mAdc?

The field two-wire pressure transmitter needs power supply. First, it is necessary to ensure that there is still a certain current in the case of zero position. Then in the design, we found that the minimum starting current of the transmitter is 3.5mA, which means that the transmitter can still work under 3.5mA.

Then if it is 0mA, then there is no power supply and it cannot work.

So use 4mA as the zero position, if it starts at 0mA, the meter will not work. If there is a disconnection in the field, there is no way to tell if it is a problem with the meter or the power supply. Therefore, the international general standard starts from 4mA.

The second question, why is it 20mA? Why not 30mA? Why not 100mA?

It stands to reason that the bigger the better, the higher the resolution, but it is not.

Through the observation of the gas explosion point, it is found that the spark generated when the 20mA is switched on and off will not cause the gas explosion. 20mA is a critical value, so ≤20mA is safe. If >20mA, there will be an explosion problem, so 4-20mA is a better value.

Then there are also some occasions where 0-10mA is used, which is generally not used in the process industry. It may be used in the discrete industry. There are also some occasions where 0.5v-4.5v or 0-5v are used in the discrete industry. Then for the process industry, it is mainly 4-20mA.

Sino-Inst is a pressure transmitter manufacturer, the main products include intelligent pressure transmitter, digital pressure transmitter, high temperature pressure transmitter, sanitary pressure transmitter, compact pressure transmitter, liquid level pressure transmitter transmitter, differential pressure transmitter, etc., the product series is complete, high precision, welcome to inquire!

Extended Reading: Smart pressure transmitter

Frequently
Asked
Questions

In fact, we believe that there is no best pressure sensor, only the most suitable pressure sensor.
There are thousands of pressure sensor brands and models on the market. Each type of pressure sensor has its own advantages. Therefore, only a pressure sensor that satisfies specific measurement conditions is a suitable pressure sensor, that is, the best pressure sensor.

As long as we choose a pressure sensor, remember a few words: type, range, overload, medium, temperature, accuracy, signal, process connection. A suitable pressure sensor can be selected.

The high pressure sensor mainly measures pressure, that is, converts the measured pressure value into a current or voltage signal, and the converted current or voltage signal can be processed by the circuit and output to meet the standard.

Simply put, the function of the high pressure sensor is to feel the measured value within a specified range and convert it into a signal according to a certain law.

With the development of technology, high pressure sensor has the most primitive mechanical structure into the current semiconductor material structure. So its volume and weight are greatly improved. No longer as bulky and large as before. In addition, the sensitivity and accuracy are also greatly improved, and the installation and debugging are extremely convenient.

Read more about: Features of SI-702 High Pressure Sensor

The two most commonly used types of pressure sensors are diffused silicon and capacitive.

Pressure transmitters can be categorized into four main types:

Gauge Pressure Transmitter.
Absolute Transmitters.
Differential-Pressure Transmitter.
Multivariable Pressure Transmitters.

High pressure transducer is used to measure high pressure up to 1500Mpa. Also called ultra high pressure transducer.

High pressure transducer adopts ultra high pressure design. Suitable for high pressure applications up to 15000bar. SI-702S series ultra high pressure pressure transducer can provide reliable ultra-high pressure measurement. Ultra high pressure transmitter adopts rare metal alloy material. After special process treatment, integrated design. All stainless steel welding package. Laser resistance temperature compensation. With high performance digital processing circuit. The factory has undergone high and low temperature aging and long-term fatigue tests. Good long-term stability. Ultra-long working life. Maintain safe and stable operation in the ultra-high pressure range.

The pressure sensor converts non-electrical physical quantities such as gravity, pressure, liquid level, material characteristics, etc. into electrical signals or directly sends physical quantities such as pressure, liquid level, etc. to the pressure transmitter.

The pressure transmitter is to amplify the weak electrical signal collected by the pressure sensor in order to transmit or start the control element. Or a signal source that converts the non-electrical input from the sensor into an electrical signal and amplifies it for remote measurement and control. The analog quantity can also be converted into a digital quantity as required.

The pressure sensor and the pressure transmitter together constitute an automatically controlled monitoring signal source. Different physical quantities require different pressure sensors and corresponding pressure transmitters.

Flat Pressure Sensor for High Viscosity Fluids

Posted on August 16, 2022 by KimGuo11

Flat Pressure Sensor is a type of pressure sensor that specifically refers to the measurement diaphragm without pressure holes. Also known as a flat film pressure sensor.

Flat Pressure Sensor is a special pressure sensor most commonly used in industrial automatic control. It is widely used in the pressure measurement and control of viscous media such as chemical coatings, paints, mud, asphalt, crude oil, etc. It solves the problem that conventional products are easy to block and cannot be used continuously, etc. defect.

The Flat Pressure Sensor elastomer adopts imported materials, diaphragm isolation technology, no pressure holes in the test head, and no viscous medium clogging during the measurement process.

Main parameters of Flat Pressure Sensor

Range:	0-0.6, 1, 5, 10, 20, 30, 40, 50～200MPa
Comprehensive accuracy:	0.1%FS, 0.2%FS, 0.5%FS
Output signal:	4-20mA (two-wire system), 0-5/1-5/0-10VDC (three-wire system)
Supply voltage:	24VDC (10-30VDC)
Medium temperature:	-20～85℃～450℃
Ambient temperature:	-20～85℃
Load resistance:	current output type: maximum 800Ω; voltage output type: greater than 50KΩ
Insulation resistance:	greater than 2000MΩ (100VDC
Sealing class:	IP65
Long-term stable performance:	0.1%FS/year
Vibration influence:	within the mechanical vibration frequency of 20Hz ~ 1000Hz, the output change is less than 0.1%FS
Electrical interface:	metal sealed terminal, four-core aviation connector
Mechanical connection:	M20×1.5, G1/2-14, etc. Other threads can be customized according to customer requirements

Extended Reading: Fluid pressure sensor

Principle of Flat Pressure Sensor

The flat membrane pressure sensor test head adopts the pressure-free mode to ensure that there is no blockage of viscous media during the measurement process, and to ensure that the pressure detection works normally.

It adopts super-large diaphragm design, the core adopts highly sensitive material, diaphragm isolation technology, and integrated structure design.

The medium and high temperature pressure-sensitive chip and heat pipe structure are used in the measurement of high temperature medium, which effectively solves the drawbacks that the electronic components inside the sensor cannot withstand high temperature.

Extended Reading: Resistive Pressure Transducer

Application of Flat Pressure Sensor

Pressure measurement and control of viscous media such as chemical coatings, paints, mud, asphalt, and crude oil;
Viscous liquid, fluid;
It is suitable for pressure measurement and control in harsh working environment, explosion-proof and explosion-proof occasions;

Extended reading: LCD Display Oval Gear High Viscosity Flow Meter

We also supply a variety of chemical flow meters in corrosion-resistant materials.

More Featured Pressure Transmitters

**Remote Seal Differential Pressure Transmitter**

**Extended Diaphragm Seal DP Level Transmitter**

Frequently
Asked
Questions

Flow Meter Selection Guide 101: Find the Perfect Fit for Your Application

A pressure transducer often called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal.

Although there are various types of pressure transducers, one of the most common is the strain-gage base transducer.

The conversion of pressure into an electrical signal, is achieved by the physical deformation of strain gauges, which are bonded into the diaphragm of the pressure transducer, and wired into a Wheatstone bridge configuration.

Pressure applied to the pressure transducer produces a deflection of the diaphragm, which introduces strain to the gages.

The strain will produce an electrical resistance change proportional to the pressure.

Extended reading: Pressure transmitter working principle

Fluid Pressure Sensors refers to sensors that can be used to measure the pressure of liquid media. Such as measuring pressure of Oil, Fuel and other fluid systems (select a sensor with the appropriate range for your system). Fluid Pressure Sensors have important uses. For example, the direct measurement of pressure in a fluid line. For example, put Fluid Pressure Sensors into the liquid, measure the liquid pressure, and estimate the liquid level. For example, by measuring the differential pressure of Fluid, the flow rate of the pipeline can be calculated.

Extended reading: How do fluid pressure sensors work?

There are many types of pressure sensors. Such as resistance strain gauge pressure sensors, semiconductor strain gauge pressure sensors, piezoresistive pressure sensors, inductive pressure sensors, capacitive pressure sensors, resonant pressure sensors, etc.

Extended reading: wireless pressure transmitter working principle

Currently, the most widely used pressure sensors include:

Diffused silicon piezoresistive pressure sensor,
Ceramic piezoresistive pressure sensor,
Sputtering thin film pressure sensor,
Capacitive pressure sensor,
Sapphire pressure sensor with high temperature resistance.
But the most widely used is the piezoresistive pressure sensor, which has a very low price, high accuracy and good linearity.

Extended Reading: Electronic Pressure Switch for Air Compressor

Non Contact Flow Meters Measure Liquid Flow

Posted on August 14, 2022 by KimGuo11

What is non contact flow meter?

Non Contact Flow Meters refers to flow meters that can achieve flow measurement without contacting the fluid medium. No need to destroy the pipeline. Easy to install and remove. This is a good choice for many pipes with strict hygiene requirements or only temporary measurements.
Non Contact Flow Meters supplied by Sino-Inst are suitable for various pipe material requirements: stainless steel pipe, carbon steel pipe, copper pipe, plastic pipe (PVC, PVDF, PPR, PPH, HDPE, etc.). It can also meet the measurement of different clean fluids: various acids, chemical solvents, alcohol, beverage water, Coca-Cola, etc.

RFQ Flow Meters

Featured Non Contact Flow Meters

Types of Non Contact Flow Meters

Currently, the main Types of Non Contact Flow Meters on the market are ultrasonic flow meters and radar flow meters.

Non-contact ultrasonic flowmeters account for 90% of non-contact measurement applications. Mainly used for flow measurement of various pipeline fluids.

Non-contact radar flowmeter is suitable for non-contact flow measurement of rivers, channels, pipelines, etc.

Clamp-on ultrasonic flowmeters utilize ultrasonic technology for easy and quick installation. Applicable to a variety of materials and pipes of different diameters. Delivers incredible measurement results even when compared to electromagnetic flow products.

The non contact ultrasonic flow meter only needs to install a very small ultrasonic sensor on the outside of the pipe without destroying the pipe. It can provide completely reliable measurement results while saving a lot of installation costs.

The transducer and the converter are connected by a special signal transmission cable. In the case of fixed measurement, a junction box should be installed in an appropriate place. Clamp-on transducers usually also require mounting clamps and couplant.

Extended reading: Totalizing flow meter water

Non-contact radar flowmeters are used for flow measurement in drains, drains, and rivers. Suitable for surface flow velocity for easy measurement. It can be used for long-term flow monitoring of various non-full drainage pipes, open channels (rectangular, trapezoidal, etc.), weirs, grooves, etc. and surface runoff. Instantaneous liquid level, flow rate and flow can be automatically recorded.

It can work stably in complex environments such as inspection wells that are wet, full of toxic and harmful, flammable and explosive gases. Due to non-contact, it is suitable for monitoring of fast flow monitoring points. And compared to contact equipment, installation and maintenance are simpler. But it cannot work under long-term immersion and overflow conditions.

It can meet the needs of system monitoring and data transmission without AC power and network access. And has excellent sealing performance, with anti-corrosion, explosion-proof function.

It can be maintenance-free on a daily basis, run regularly for inspection, and no need for manual on-duty. Measurement information can be stored locally and sent wirelessly. With early warning and cloud management functions, it can be set remotely.

Strap on Flow Meter for Small Pipes Φ9.53~Φ90

Strap on flow meter X3 is widely used in flow measurement and monitoring in the production process.

Strap on flow meter X3 can meet the needs of different pipe materials: stainless steel pipe, carbon steel pipe, copper pipe, plastic pipe (PVC, PPR, PPH, HDPE), etc.

Strap on flow meter X3 almost meets the measurement of different clean fluids: various acids, alcohols, chemical solvents, alcohol, drinking water, Coca-Cola water… etc.

Product	Strap on Flow meter
Model	X3
Flow range	0.1m/s~5.0m/s
Accuracy	±2.0%
Repeatability	0.80%
Pipe size	φ6.35~φ90
Data storage	Daily, monthly, and Annual. Flow Totalizer
Analog output	4~20mA, Maximum load: 600Ω
Alarm output	DCT, Upper and lower limit alarm function(optional)
Communication	RS485,support Modbus communication protocol
Power supply	24VDC
Cable length	2.0m
Keypad	Four light touch buttons
Screen	OLED 128*64 displayscreen
Units	Metric and imperial units are available, Cubic Meters(m3), Liters(L), USA Gallons(GAL)/hour,/min,Default unit setting:m3/h
Totalizer	Six bit digit
Piper material	Stainless steel pipe, carbon steel pipe, copper pipe, plastic pipe
Case material	Aluminum alloy
Environment temp.	0℃~50℃（32°F~122°F)
Medium temp.	0℃~50℃（32°F~122°F)
Environment humidit	0-95% relative humidity, without condensation
IP Grade	IP54

Extended Reading: Types Of Crude Oil Flow Meters

More Featured Liquid Flow Meters

Non Contact Liquid Measurement Solutions

Clamp on Water Flow Meter
What is Clamp on Water Flow Meter? Clamp on Water Flow Meter is also known as the clamp-on…
Strap on Ultrasonic Flow Meters
What is Strap on Ultrasonic Flow Meters? Strap on Ultrasonic Flow Meter is also often called Clamp On…
Ultrasonic Flow Detectors
Ultrasonic flow detectors are an important part of ultrasonic flow meters. Ultrasonic flow detectors are also called ultrasonic…
How to Select Ultrasonic flow detectors?
What is an ultrasonic flow detector? An ultrasonic flow detector is often understood as an ultrasonic flow meter…
Ultrasonic water flow meters | Accurate and Easy solution
The ultrasonic water flow meter is a meter that measures water flow by detecting the effect of water…
Cheap flow meters-Low Cost measurement solutions
Cheap flow meters means to choose the lowest cost flow meter while satisfying your measurement needs. How to…
Clamp on Flow Meters for Liquid Pipes
Clamp on flow meters refers to the non-contact flow meter, or strap-on flow meters, which clamps the ultrasonic…
Ultrasonic flow measurement
Ultrasonic flow meters, using the ultrasonic principle, measure the velocity of flow. We can use a different type…

Gas and Liquid Measurement Solutions

Mechanical Oil Flow Meters
What is mechanical oil flow meter? Mechanical oil flow meter refers to a flowmeter that can detect the volume flow…
Kerosene Gasoline/ Kerosene Flow Meter
A kerosene flow meter is a flow meter that can be used to measure the flow of kerosene. Kerosene is…
Slurry Flow Meter
Flow Meter for Slurry Application Slurry is a product of domestic sewage and industrial wastewater treatment. Slurry consists of solid…
Digital Flow Meter for Argon Gas
What is Digital Flow Meter for Argon Gas? Digital flow meter for argon gas refers to a flow meter that…
PD Flow Meters Selection and Application | Oil-Liquid
What is PD flow meter? PD flow meters (positive displacement flow meters) are the only flow measurement technology that directly…
Guide for Digital Fuel Flow Meter
Digital Fuel Flow Meter is a flow meter dedicated to measuring fuel, diesel, gasoline, and petroleum. Digital Fuel Flow Meter…
Mechanical Water Flow Meters
Mechanical water flow meters refer to a type of flow meter suitable for clean water processes or applications. The working…
Explore Oil and Gas Flow Meters
An oil and Gas Flow Meter is A device installed in a pump manifold or treating line to measure the…
Gear Flow Meter-High Viscosity Fluid-Micro Flow Solution
A gear flow meter is a common positive displacement flow meter. The gear flow sensor has built-in double gears to…
Molasses Flow Meters-High Viscosity Liquids Solution
Molasses flow meters are a type of flow meter used for molasses flow measurement. Molasses are common high viscosity liquids…
Solvent flow meters
The solvent flow meter is a flow meter that can measure solvent volume or mass flow. In the industrial production…
Grease Flow Meters
What is a Grease Flow Meter? Grease Flow meters are meters dedicated to measuring the volume or mass flow of…
How does a residential water meter work?
What does a residential water meter look like? A residential water meter is a legal meter for measuring water consumption…

Frequently
Asked
Questions

If you let me answer this question. I would like to divide flow meters into two categories: mass flow meters and volumetric flow meters.

Of course, it can also be divided according to the measurement medium. There are two types of flow meters for measuring gas and measuring liquid.

Perhaps, we can also divide into closed pipeline measurement and open channel measurement according to the situation of the pipeline.

Finally, we may also be able to divide into contact and non-contact measurements according to the contact situation of the medium.

Non-invasive flow meter is also known as non-contact flow meter. When measuring the fluid flow of the pipeline, there is no need to cut and open the pipeline. easy to use.

If the flowmeter is divided into 5 categories. Then the five commonly used flowmeters are:

Electromagnetic flowmeter
Differential pressure flowmeter
Turbine flowmeter
Ultrasonic flowmeter
Volumetric flowmeter (PD)

Extended reading: How to choose a high viscosity flow meter?

Sino-Inst is Manufacturer of Non Contact Flow Meters. We supply more than 20 kinds of Non Contact Flow Meters. 90% ultrasonic flowmeters, and other types of flowmeters.

Non Contact Flow Meters are mainly used for flow measurement of various liquids.
It can measure even liquids such as water, seawater, oil, and slurry.

Non Contact Flow Meters enable stable flow measurement without piping modifications. This greatly meets the measurement needs of many applications. Can be used from small to large tubes. For efficient non-contact flow measurement of flexible and rigid plastic pipes.

Sino-Inst’s Non Contact Flow Meters, made in China, Having good Quality, With better price. Our flow measurement instruments are widely used in China, India, Pakistan, the US, and other countries.

The entire team at Sino-Inst’s has received excellent training, so we can ensure that every client’s needs are met. For assistance with your product requirements, whether it’s a non-contact flow sensor, level sensor, or other device, give us a call.

Request a Quote

Please enable JavaScript in your browser to submit the form

What Is Resistive Pressure Transducer?

Posted on August 4, 2022 by KimGuo11

What Is Resistive Pressure Transducer?

Resistive pressure transducers are also called resistance pressure transducers. It is a commonly used pressure sensor. Pressure sensors are generally distinguished by principle: capacitive pressure transmitters, resistive pressure transducers, inductive pressure transmitters, semiconductor pressure transmitters, and pressure transmitters for high-frequency measurement. Among them, resistance pressure transmitters are commonly used.
Resistance strain pressure sensor is a kind of resistance pressure sensor. It measures the pressure value by the resistance change of the strain gauges bonded to the elastic element.

Featured DP transmitters.

Resistive Pressure Transducer Working Principle

The functional principle of a resistive pressure transducer is very simple. A pressure sensor converts a mechanical pressure value into a proportional electrical signal. Pressure sensors usually consist of a body and a (thin) diaphragm.

The electrical components of resistance pressure transmitters that feel pressure are generally resistance strain gauges. Resistance strain gauges are sensitive devices that convert the pressure on the measured component into an electrical signal.

The diaphragm is the most important element for pressure measurement and is equipped with strain-sensitive and piezoresistive structures, so-called strain gauges. The diaphragm deflects under pressure.

The most widely used resistance strain gauges are metal resistance strain gauges and semiconductor strain gauges. There are two types of metal resistance strain gauges: filamentary strain gauges and metal foil strain gauges.

Usually, the strain gauge is tightly bonded to the matrix that generates mechanical strain through a special adhesive. When the stress of the matrix changes, the resistance strain gauge also deforms together, which changes the resistance value of the strain gauge. The voltage across the resistor changes.

For example, if a resistor is connected to a Wheatstone measurement bridge, an electrical signal can be measured and transmitted to the indicator.

Extended reading: High accuracy pressure transducers

Types of Pressure Transducers

Let’s talk about the classification of transmitters:

According to the working principle of the sensor, it can be divided into resistance, capacitance, inductance, semiconductor, etc.;
According to the classification of sensor chips, it can be divided into metal, ceramic, diffused silicon, sapphire, etc.;
According to the measurement range, it can be divided into differential pressure, gauge pressure, absolute pressure, high static pressure and differential pressure, etc.;

Resistive pressure transducers are the most widely used transmitters and have the advantages of high cost performance and good linearity characteristics.

Extended Reading: 4 wire pressure sensor wiring diagram

Types of Resistance Pressure Transducers

Resistive pressure transducers are generally divided into metal, ceramic, and diffused silicon according to pressure-sensitive components.

The difference between the three:

The metal pressure transmitter has poor accuracy, but the temperature effect is small, and it is suitable for fields with a wide temperature range and low accuracy requirements.
The accuracy of ceramic pressure sensors is better, but it is greatly affected by temperature. Another advantage of ceramics is impact resistance and corrosion resistance.
Diffusion silicon pressure transmitter has high precision and large temperature drift, so it is generally necessary to perform temperature compensation before it can be used. And even after temperature compensation, pressures above 125°C cannot be measured. However, under normal temperature conditions, the sensitivity coefficient of diffused silicon is 5 times that of ceramics. Therefore, it is generally used in the field of high-precision measurement, but the accuracy is low in the micro-range.

Extended Reading: Smart pressure transmitter

Piezoresistive pressure sensor refers to a sensor made by using the piezoresistive effect of single crystal silicon material and integrated circuit technology.

After the single crystal silicon material is subjected to the force, the resistivity changes, and the electrical signal output proportional to the force change can be obtained through the measurement circuit.

It is also known as a diffused silicon piezoresistive pressure sensor. It is different from the adhesive strain gauge, which needs to indirectly feel the external force through the elastic sensitive element, but directly feels the measured pressure through the silicon diaphragm.

Capacitive pressure transducer (capacitive type pressure transducer) is a pressure sensor that uses capacitive sensing elements to convert the measured pressure into an electrical output that has a certain relationship with it. The characteristics are that the input energy is low, the dynamic response is high, the natural effect is small, and the environmental adaptability is good.

It generally uses a circular metal film or a metal-plated film as an electrode of the capacitor. When the film is deformed by pressure, the capacitance formed between the film and the fixed electrode changes. By measuring the circuit, the output voltage has a certain relationship with the voltage. electric signal.

Capacitive pressure sensors belong to the polar distance variable capacitive sensors, which can be divided into single capacitive pressure sensors and differential capacitive pressure sensors.

Extended Reading: MEMS Pressure Sensors

The differential pressure transmitter is a transmitter that measures the pressure difference between the two ends of the transmitter, and outputs a standard signal (such as 4~20mA, 0~5V).

Differential pressure transmitters are different from general pressure transmitters in that they have 2 pressure interfaces. Differential pressure transmitters are generally divided into positive pressure ends and negative pressure ends.

In general, the pressure at the positive pressure end of the differential pressure transmitter should be greater than the pressure at the negative pressure section to measure.

The differential pressure transmitter is used to prevent the medium in the pipeline from directly entering the transmitter, and the pressure-sensitive diaphragm and the transmitter are connected by a capillary filled with fluid.

It is used to measure the liquid level, flow and pressure of liquid, gas or steam. Then convert it into 4～20mA DC signal output.

Potentiometric pressure transducers are usually used for displacement, level and angle measurement.

The measured component is connected to the rotating shaft (or sliding arm) of the potentiometer through a certain mechanical transmission part. When the measured change changes, the sliding arm moves, and the resistance from the center of the potentiometer to the two fixed ends changes differentially.

The resistance change of the potentiometer can be converted into a voltage change output through a voltage divider circuit or a bridge circuit, and after A/D conversion, the measured physical quantity can be accurately measured. !

The hydraulic pressure transducer is mainly used in the pressure measurement of industrial equipment such as construction machinery, special equipment, compressors, injection molding machines, and servo equipment. It has good waterproof, small size and high cost performance. It is easy to install. The whole structure is made of stainless steel, which has good sealing, vibration resistance and stable and reliable performance.

Hydraulic pressure transducer is the extension and development of pressure transmitter technology. According to the principle that the pressure generated by different specific gravity liquids at different heights is linear. Realize the accurate measurement of the volume, liquid height and weight of water, oil and paste. Measure and transmit.

Extended Reading: Liquid pressure sensor

Our pressure transmitters can also be upgraded to Low power-battery powered Wireless Pressure Sensors.

Strain Gauge Pressure Transducer Working Principle

The strain gauge pressure transducer works based on the principle of resistance strain effect.

There are two types of resistance strain gauges: metal strain gauges (wire or metal foil) and semiconductor strain gauges. The measured pressure strains the strain gauge.

When the strain gauge produces compressive strain, its resistance decreases. When the strain gauge produces tensile strain, its resistance increases.

The resistance value of the strain gauge changes, and then the corresponding millivolt-level potential output is obtained through the bridge circuit. The measured pressure is displayed by a millivoltmeter or other recording instruments. Thus, a strain gauge pressure gauge is formed.

Strain gauge structure: It consists of three parts: strain sensitive element, substrate and cover layer, and lead wire. Strain-sensitive elements are generally composed of metal wires and metal foils (high resistivity materials), which convert mechanical strain into changes in resistance. The substrate and cover layer serve to fix and protect sensitive components, transmit strain and electrically insulate.

Resistance strain pressure sensor structure: diaphragm type, cylinder type, combined type. Among them, the diaphragm type is suitable for low pressure measurement; the cylinder type is suitable for high pressure measurement.

The working mode of the resistance strain pressure sensor: the change of resistance is converted into the output of current or voltage signal through the unbalanced bridge.

Featured Air pressure transducer

**SI-300 Pressure Transducer 4-20mA/Voltage**

**SI-390 Industrial Pressure Transmitter**

SI-512H High Temperature Pressure Sensor

Featured Digital pressure transducer

**Diffused silicon Gauge Pressure Transmitter**

**Capacitive Gauge Pressure Transmitter**

**Hygienic / Sanitary Pressure Transmitter**

Frequently
Asked
Questions

Classification of working principle of pressure sensor

Piezoresistive pressure sensor
Ceramic pressure sensor
Diffusion silicon pressure sensor:
Sapphire pressure sensor:
Piezoelectric pressure sensor:

Extended reading: Pressure Sensor Applications-Featured Industry Applications

Using a multimeter to test the pressure sensor can only perform simple tests, and the test results are only for reference.
There are roughly three tests that can be performed:

Bridge detection:
It mainly detects whether the circuit of the sensor is correct. Generally, it is a Wheatstone full-bridge circuit, which uses the ohm gear of the multimeter to measure the impedance between the input terminals and the impedance between the output terminals. These two impedances are the input and output of the pressure sensor. impedance. If the impedance is infinite, the bridge is disconnected. It means that there is a problem with the sensor or the definition of the pin is not correctly judged;

Detection of zero point:
Use the voltage range of the multimeter to detect the zero output of the sensor without applying pressure. This output is generally a mV level voltage. If it exceeds the technical specifications of the sensor, it means that the zero point deviation of the sensor is out of range;

Pressure detection:
The method of checking the order is: supply power to the sensor, blow the air guide hole of the pressure sensor with the mouth, and use the voltage range of the multimeter to detect the voltage change at the output end of the sensor. If the relative sensitivity of the pressure sensor is large, this amount of change will be significant. If there is no change at all, you will need to switch to an air pressure source to apply pressure.

These types of sensors are also called pressure transmitters. Because 4-20mA signals are least affected by electrical noise and resistance in the signal line, these sensors are best used when signals must be transmitted over long distances. These sensors are typically used in applications where the lead must be 1000 feet or more.

Read more about: What Is 0-10V Signal Output?

What Is a Fluid Pressure Sensor?

Posted on July 25, 2022 by KimGuo11

What Is a Fluid Pressure Sensor?

Fluid Pressure Sensors refers to sensors that can be used to measure the pressure of liquid media. Such as measuring pressure of Oil, Fuel and other fluid systems (select a sensor with the appropriate range for your system). Fluid Pressure Sensors are also called liquid pressure sensor or liquid pressure transducer. Fluid Pressure Sensors have important uses. For example, the direct measurement of pressure in a fluid line. For example, put Fluid Pressure Sensors into the liquid, measure the liquid pressure, and estimate the liquid level. For example, by measuring the differential pressure of Fluid, the flow rate of the pipeline can be calculated.

Differential pressure flow meter advantages and disadvantages

What is a pressure sensor?

Typically, a pressure sensor (sometimes called a pressure transducer or pressure transmitter) is used to measure the pressure of a fluid (gas or liquid).
Pressure is an expression of the force required to stop a fluid from expanding, and is usually expressed in force per unit area.
Pressure sensors generate electrical signals related to the applied pressure. Such signals are usually digital or analog, but optical, visual and auditory signals are also common.
Industrial pressure sensors, also known as pressure transducers, pressure transmitters, pressure indicators and pressure switches.

Extended Reading: Smart pressure transmitter working principle

How do fluid pressure sensors work?

An instrument for measuring fluid pressure. Usually the measured pressure is compared to a reference pressure (such as atmospheric pressure or other given pressure), thus measuring the relative pressure or pressure difference.

According to the working principle, it can be divided into three types: liquid column, elastic and sensor.

The principle of the pressure sensor is to convert the pressure signal into an electrical signal. Such as strain type, elastic element deformation caused by resistance change. Piezoelectric, the use of piezoelectric effect.

Various pressure sensors can be miniaturized, more accurate and fast to measure, especially to measure dynamic pressure, realize multi-point inspection, signal conversion, long-distance transmission, computer connection, timely processing, etc., so as to develop rapidly and widely used.

Extended reading : Types of pressure sensors

Applications of fluid pressure sensors

Fluid pressure sensors are mainly used in: construction machinery, hydraulic and pneumatic systems, petrochemicals, energy and water treatment, water conservancy and hydropower, compressors and other fields:

In the hydraulic system, the pressure sensor is mainly used to complete the closed-loop control of the force. Extended reading: Hydraulic oil flow measurement solutions.

When the control spool moves suddenly, a peak pressure several times the working pressure of the system will be formed in a very short period of time.

In typical mobile and industrial hydraulics, any pressure sensor can quickly be destroyed if not designed with such extreme conditions in mind.

Shock-resistant pressure sensors are required. There are two main ways for pressure sensors to achieve shock resistance, one is a strain gauge chip, and the other is an external coil. Generally, the first method is used in hydraulic systems, mainly because Easy to install.

Another reason is that the pressure sensor is subject to constant pressure pulsations from the hydraulic pump.

Extended reading: extrusion melt pressure transducer

Fluid pressure sensors are often used in safety control systems, such as the safety management system of the air compressor itself.

In the field of security control, the application is generally considered from the performance aspect, as well as the safety and convenience of the actual operation.

The fluid pressure sensor can install some components and signal conditioners and other devices on a very small chip through materials and advanced processing technology. Therefore, its small size is also its advantage. Of course, it can also improve the accuracy of system testing to a certain extent. .

In the safety control system, the pressure brought by the compressor is controlled to a certain extent by installing a pressure sensor in the piping equipment of the air outlet. This is a certain protection measure and a very effective control system.

When the compressor starts normally, if the pressure value does not reach the upper limit, then the controller will open the air inlet and adjust the equipment to reach the maximum power.

Extended Reading: Resistive Pressure Transducer

Fluid pressure sensors play an important role in injection molds.

It is installed in the nozzle of the injection molding machine, the hot runner system, the cold runner system and the cavity of the mold to measure the distance between the nozzle of the injection molding machine and the cavity during the injection molding, filling, pressure holding and cooling of the plastic. plastic pressure.

Extended reading: High Pressure Hydraulic Flow Meter

There are many kinds of pressure sensors, for the special environment of mine pressure monitoring.

Mine pressure sensors mainly include: semiconductor piezoresistive pressure sensors, metal strain gauge pressure sensors, differential transformer pressure sensors, etc.

The above sensors are widely used in the mining industry, and the specific sensor to be used needs to be selected according to the specific mining environment.

Extended reading: High Pressure Flow Meters for Liquids-Steam-Gas

Pressure sensors are commonly used in air compressors, as well as air conditioning and refrigeration equipment. These sensor products are small in size and easy to install. In addition, the pressure guide port generally adopts a special valve needle design.

Extended reading: Pressure Sensor Applications In Various Industries

Read more about: Calculation Of Pressure Drop

Pressure Sensor For Liquid Level Measurement

In physics, the pressure P of a liquid is determined by the relationship: p=pgh.

For the same kind of liquid, the liquid density p is constant. Therefore, the pressure P of the liquid is linearly proportional to the height h of the liquid surface (the height from the liquid surface).

It is not difficult to find that the pressure of the liquid at different heights of the liquid level is also different.

As shown in the figure above, when the pressure sensor is used to measure the liquid level, the pressure sensor is installed at the bottom of the tank. When the liquid level in the tank changes, the height h from the tank bottom to the liquid level also changes at the same time, and the pressure naturally changes accordingly, thus achieving the purpose of continuous measurement.

One of the advantages of using pressure sensors for liquid level measurement is non-contact. Compared with mechanical and static methods, when measuring, it does not require too many parts to contact the liquid, and the installation is relatively convenient.

In addition, in terms of measurement principle, compared with similar non-contact measurement methods such as laser and ultrasonic, the relationship of pressure sensor measurement principle is simpler and linear, and it is more intuitive in data processing, analysis and processing.

Extended reading: Differential pressure level transmitter working principle

Pressure Sensors For Flow Measurement

The pressure of the fluid is an extremely important parameter in flow measurement. Differential pressure flowmeter uses the pressure difference at both ends of the throttling element to realize flow measurement.

In addition, the working pressure of the flowmeter can be known through pressure measurement, and necessary correction calculations are performed to ensure the accuracy of flow measurement.

Extended reading: flow rate and pressure relationship

Upstream and Downstream Flow Straight Pipe Requirements-for Flowmeter Installation

fluid depth pressure sensor

If we make the pressure sensor into a submersible sensor, it can be used to measure the depth of the liquid.

The most common fluid depth pressure sensor is what we often call the submersible hydrostatic pressure sensor. Used to measure the depth or level of liquids such as water, fuel.

Hydrostatic level measurement is often used for tank level measurement. Hydrostatic level measurement is one type of continuous level measurement.

Hydrostatic pressure sensors are used to measure the level or fill height of liquids. Hydrostatic pressure measurement is suitable for liquid level measurement due to the static pressure effect of non-flowing fluids. This physical principle describes the effect of the gravity of a stationary (i.e. non-flowing) liquid on the measurement point. This gravity is often described as “hydrostatic pressure”.

Related pressure transmitter

**SI-350 Sanitary Pressure Transmitter**

**High Frequency Dynamic Pressure Sensor**

Frequently
Asked
Questions

Nonlinear error: This is a factor that has little effect on the initial error of the pressure sensor. The reason for the error is the physical nonlinearity of the silicon chip, but for sensors with amplifiers, the nonlinearity of the amplifier should also be included, the linearity error curve can be a concave or convex dynamometer.
Offset error: Since the vertical offset of the pressure sensor remains constant over the entire pressure range, the diffusion variation of the converter and laser trim correction will generate offset errors.
Sensitivity error: The magnitude of the error is proportional to the pressure, if the sensitivity of the device is higher than the typical value, the sensitivity error will be an increasing function of the pressure. If the sensitivity is lower than typical, then the sensitivity error will be a decreasing function of pressure. The cause of this error is a change in the diffusion process.
Hysteresis error: In most cases, the hysteresis error of the pressure sensor can be completely ignored. Because the silicon chip has high mechanical stiffness. Typically, only hysteresis errors need to be considered when pressure changes are large.

Four errors of pressure sensors are inevitable. We can only choose high-precision production equipment. Using high technology to reduce these errors, it is also possible to perform error calibration at the factory and try to reduce errors as much as possible. Therefore, you don’t need to pay too much attention when using it, but try to reduce these errors as much as possible.

Extended Reading: MEMS Pressure Sensors

Please note that Pressure Transmitter Calibration is required after the pressure transmitter has been used for a period of time. In order to ensure the accuracy of the quantity.

A pressure transducer often called a pressure transmitter, is a transducer that converts pressure into an analog electrical signal.

Although there are various types of pressure transducers, one of the most common is the strain-gage base transducer.

Pressure applied to the pressure transducer produces a deflection of the diaphragm, which introduces strain to the gages.

The strain will produce an electrical resistance change proportional to the pressure.

Extended reading: Pressure transmitter working principle

Of course, you can install a pressure gauge.

Pressure transmitters can be categorized into four main types:

Gauge Pressure Transmitter.
Absolute Transmitters.
Differential-Pressure Transmitter.
Multivariable Pressure Transmitters.

Extended reading: High accuracy pressure transducers

Flow is an important parameter in industrial production and life. The amount of fluid flowing through a section of a pipe per unit time is called instantaneous flow. Instantaneous flow is divided into volume flow and mass flow. A flow sensor is a sensor that measures the flow of a fluid. Flow sensor is an important instrument in measurement technology, it is widely used in industrial process control, life science and technology, commercial application, military and other fields. In recent years, with the development of science and technology and the development of human needs, flow sensors are also constantly developing.

Extended reading: Digital Flow Meters

In the hydraulic system, the closed-loop control of the force is mainly caused by the pressure sensor.
The working principle of the pressure sensor in the hydraulic system is that the pressure acts directly on the diaphragm of the sensor. Make the diaphragm produce micro-displacement proportional to the medium pressure. Causes the resistance of the sensor to change. And by using an electronic circuit to detect the change, a standard signal corresponding to the pressure is converted and output.

Sino-Inst offers over 50 pressure sensors for fluid measurement. About 50% of these are differential pressure flow meters, 40% is the liquid pressure sensor, and 20% are pressure Level Transmitter.

A wide variety of Fluid Pressure Sensors options are available to you, such as free samples, paid samples.

Sino-Instrument is a globally recognized supplier and manufacturer of pressure measurement instrumentation, located in China.

Request a Quote

Please enable JavaScript in your browser to submit the form