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RTD vs Thermocouple

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RTD vs Thermocouple- What is the difference? What are they used for?

Both RTDs and thermocouples are sensors used to measure heat such as Fahrenheit and Kelvin. Both thermocouple and thermal resistance belong to contact temperature measurement in temperature measurement. Although its role is to measure the temperature of the object the same. But their working principles and characteristics are different. Thermocouple is the most widely used temperature device in temperature measurement. Thermal resistance does not require compensation wires and is cheaper than thermocouples.

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RTD vs Thermocouple

As two major contact temperature sensors: thermocouple and thermal resistance. Their names differ by only one word and both can be used as sensors for measuring object temperature.

The choice of thermocouple or thermal resistance should be judged according to the measured object environment. Many people are not sure what to choose. Therefore, it is necessary to fully understand the difference between thermal resistance and thermocouple temperature sensor when choosing a temperature sensor.

RTDs stands for ‘Resistance Temperature Detectors’

Thermal resistance: no compensation wire is needed, the price is cheaper

The principle of temperature measurement of thermal resistance: based on the characteristics of the resistance of conductors or semiconductors that change with temperature.

Thermal resistance is one of the most commonly used temperature detectors in medium and low-temperature areas. The thermal resistance temperature measurement is based on the characteristic that the resistance value of the metal conductor increases with the increase in temperature for temperature measurement.

The advantage of thermal resistance: It can also transmit electrical signals remotely. High sensitivity and strong stability. Interchangeability and accuracy are better. However, power supply excitation is required. The temperature change cannot be measured instantaneously.

Disadvantages of thermal resistance: Although thermal resistance is widely used in industry. But because of his temperature measurement range, his application has been limited.

Industrial thermal resistance generally uses Pt100, Pt10, Cu50, Cu100, the temperature range of platinum thermal resistance is generally minus 200-800 degrees Celsius, and copper thermal resistance is minus 40 to 140 degrees Celsius.

Thermal resistors are mostly made of pure metal materials. At present, platinum and copper are the most widely used. In addition, materials such as nickel, manganese, and rhodium have now been used to make thermal resistors.

Thermal resistance does not require compensation wires and is cheaper than thermocouples.

Thermocouple: can transmit 4-20mA electrical signal far away

Thermocouple temperature measurement principle:

The principle of thermocouple temperature measurement is based on the thermoelectric effect. Connect two different conductors or semiconductors into a closed loop. When the temperature at the two junctions is different. The thermoelectric potential will be generated in the loop. This phenomenon is called the thermoelectric effect, also known as the Seebeck effect.

The thermoelectric potential generated in the closed-loop is composed of two kinds of electric potential. Thermoelectric potential and contact potential.

Thermoelectric potential refers to the electric potential generated by the temperature difference between the two ends of the same conductor.

Different conductors have different electron densities, so they generate different electric potentials.

The contact potential, as the name implies, refers to when two different conductors are in contact. Because their electron densities are different, a certain amount of electron diffusion occurs. The electric potential formed when they reach a certain equilibrium. The magnitude of the contact potential depends on the material properties of the two different conductors and the temperature of their contact points.

The advantages of thermocouples:
Wide temperature measurement range. The performance is relatively stable. At the same time, the structure is simple. The dynamic response is good. It can transmit 4-20mA electrical signals remotely. It is convenient for automatic control and centralized control.

Thermocouples currently used internationally have a standard specification. Internationally, thermocouples are divided into eight different divisions, namely B, R, S, K, N, E, J, and T. The lowest temperature can be measured at minus 270 degrees Celsius and the highest can reach 1800 degrees Celsius.

Among them, B, R, and S belong to the platinum series of thermocouples. Because platinum is a precious metal. So they are also called precious metal thermocouples and the remaining ones are called cheap metal thermocouples.

There are two types of thermocouples, common type, and armored type.

Ordinary thermocouples are generally composed of hot electrodes, insulating tubes, protective sleeves, and junction boxes. The armored thermocouple is a combination of thermocouple wire, insulating material, and a metal protective sleeve. A solid combination is formed by stretching.

But the electrical signal of the thermocouple needs a special wire to transmit, this kind of wire is called compensation wire.

Different thermocouples require different compensating wires, and their main function is to connect with the thermocouple to keep the reference end of the thermocouple away from the power supply so that the temperature of the reference end is stable.

Compensation wires are divided into two types: compensation type and extension type. The chemical composition of the extension wire is the same as that of the thermocouple being compensated. However, in practice, the extended wire is not made of the same metal as the thermocouple. Generally, a wire with the same electron density as the thermocouple is used instead.

The connection between the compensation wire and the thermocouple is generally very clear. The positive pole of the thermocouple is connected to the red wire of the compensation lead, and the negative pole is connected to the remaining color. Most of the general compensation wires are made of copper-nickel alloy.

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  1. Thermocouple English Thermocouple, abbreviated as TC, works on the principle of outputting a linear millivolt signal as the temperature changes. The instrument amplifies the signal and converts it into a temperature signal.
  2. Thermal resistance English Resistance abbreviation RTD working principle is: the resistance value changes linearly with temperature changes.
  3. The temperature transmitter can convert the thermocouple mV voltage signal or the resistance value signal of the thermal resistance into a 4-20mA standard signal for automation system control.
  4. Generally speaking, thermal resistance is cheaper than thermocouple.

Extended reading: RTD vs. Thermocouple: What’s the Difference, and Which Should You Use?

Here, we list some temperature measurement ranges of thermal resistance and thermocouple sensors, and the thermoelectric potential and thermal resistance values of 100°C.

Thermocouple

  • Platinum Guy 10-Platinum (Type S) (0-1300℃), T=100℃, E(100,0)=0.646mV.
  • Platinum Guy 13-Platinum (R type) (0-1300℃), T=100℃, E(100,0)=0.647mV.
  • Zhenming-Zhensi (K type) (0-1200℃) T=100℃E(100,0)=4.096mV.
  • Zhenming-Constantan (Type E) (-200-760℃), T=100℃, E(100,0)=6.319mV

Thermal resistance

  • Platinum thermal resistance (pt100) (-200-850℃), T=100℃, R=138.50Q
  • Copper thermal resistance, (Cu50) (-50-150℃), T=100℃, R=71.4Q.

RTD vs Thermocouple difference

A thermocouple is a sensor that measures temperature. It is a temperature sensor like a thermal resistance. But the main difference between thermocouple and thermal resistance lies in:

  1. The nature of the signal.

The thermal resistance itself is a resistance, and the change of temperature causes the resistance to produce a positive or negative resistance change; while a thermocouple produces a change in the induced voltage, which changes with the change of temperature.

  1. The temperature ranges detected by the two sensors are different.

The thermal resistance generally detects the temperature range of 0-150 degrees. The highest measurement range can reach about 600 degrees (of course, negative temperature can be detected).

The thermocouple can detect a temperature range of 0-1000 degrees (or even higher). Therefore, the former is low temperature detection, and the latter is high temperature detection.

  1. Different materials

From the material point of view, thermal resistance is a metal material. Metal materials with temperature-sensitive changes, thermocouples are bimetallic materials. Both two different metals.

Due to the change in temperature, a potential difference is generated at the two ends of two different metal wires.

  1. PLC modules are different

The thermal resistance corresponding to PLC and the input module of thermocouple are also different, this sentence is no problem. But generally PLC is directly connected to 4-20ma signal, and thermal resistance and thermocouple are generally equipped with transmitter before they are connected to PLC. If you connect to DCS, you don’t need to use a transmitter! The thermal resistance is the RTD signal, and the thermocouple is the TC signal!

  1. PLC also has thermal resistance module and thermocouple module, which can directly input thermal resistance and thermocouple signals.

6. Different prices

Thermocouples are available in J, T, N, K, S and other models. Some are more expensive than resistors, and some are cheaper than resistors. However, if the compensation wire is included, the comprehensive cost of the thermocouple is higher. Thermal resistance is a resistance signal, and thermocouple is a voltage signal.

  1. Different measurement principles

The principle of thermal resistance temperature measurement is based on the property of the resistance of the conductor (or semiconductor) that changes with temperature. The measurement range is minus 00 to 500 degrees. Commonly used are platinum resistance (Pt100, Pt10), copper resistance Cu50 (minus 50-150 degrees).

The principle of thermocouple temperature measurement is based on the thermoelectric effect to measure temperature. Commonly used are platinum rhodium-platinum (graduation number S, measuring range 0~1300 degrees), nickel chromium-nickel silicon (graduation number K, measuring range 0~900 degrees), nickel chromium-constantan (graduation number E, measuring range 0 to 600 degrees), platinum rhodium 30-platinum rhodium 6 (grading number B, measuring range 0 to 1600 degrees).

RTD vs Thermocouple, how to choose?

The selection of thermocouple should be based on comprehensive considerations such as the use temperature range, the required accuracy, the use atmosphere, the performance of the measurement object, the response time and the economic benefits.

  1. Selection of measurement accuracy and temperature measurement range
  • When the operating temperature is 1300~1800℃ and the accuracy is relatively high, the B-type thermocouple is generally used;
  • The accuracy is not high, and the atmosphere allows the use of tungsten rhenium thermocouples.
  • Tungsten rhenium thermocouple is generally used above 1800℃;
  • The operating temperature is 1000~1300℃, the accuracy is required and the high accuracy is available. S-type thermocouple and N-type thermocouple are available;
  • Generally use K-type thermocouple and N-type thermocouple below 1000℃;
  • Generally use E-type thermocouple below 400℃;
  • T-type thermocouples are generally used for measurement at 250°C and negative temperature. T-type thermocouples are stable and have high accuracy at low temperatures.
  1. The choice of atmosphere

S-type, B-type, and K-type thermocouples are suitable for use in strong oxidizing and weak reducing atmospheres. J-type and T-type thermocouples are suitable for weak oxidizing and reducing atmospheres. If a protective tube with better airtightness is used, the requirements for the atmosphere are not too strict.

  1. Choice of durability and thermal response

Thermocouples with larger wire diameters have better durability, but their response is slower. For thermocouples with large heat capacity, the response is slow. When measuring a temperature with a large gradient, in the case of temperature control, the temperature control is poor. It requires a fast response time and a certain degree of durability, so it is more appropriate to choose an armored couple.

  1. The nature and state of the measuring object to choose the thermocouple

The temperature measurement of moving objects, vibrating objects, and high-pressure vessels requires high mechanical strength. A chemically polluted atmosphere requires a protective tube. In the case of electrical interference, higher insulation is required.

Selection process: model-index number-explosion-proof grade-precision grade-installation and fixed form-protective tube material-length or insertion depth.

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Grease Flow Meters

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What is a Grease Flow Meter?

Grease Flow meters are meters dedicated to measuring the volume or mass flow of industrial grease fluids.

The most common Grease Flow meters are elliptical gear flow meters, also called positive displacement flowmeters. There are turbine flow meters, gear flow meters, and so on. Industrial grease can be measured online. Including hydraulic oil, steam turbine oil, refrigeration oil, heat treatment oil and heat transfer oil, etc. In addition, there are greases with lubricating oil as base oil and thickening agent.

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Industrial Grease Flow meters are different from grease guns or grease meters. Industrial Grease Flow meters need to deal with more complex conditions. The pipe diameter can range from DN10 to DN200, or even larger. So how to choose the applicable Industrial Grease Flow meters? Let’s analyze it together.

Characteristics of industrial grease

What are the types of industrial grease?

Industrial greases mainly include hydraulic oil, gear oil, turbine oil, compressor oil, refrigeration oil, transformer oil, vacuum pump oil, bearing oil, metal processing oil (liquid), anti-rust grease, cylinder oil, heat treatment oil, and heat transfer oil.

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In addition, there are greases with lubricating oil as base oil and thickening agent. The users of industrial lubricants are companies from all walks of life, and they use many varieties and large amounts.

The basic performance and main selection principle of industrial grease is viscosity. GB/T3141-94 is the ISO viscosity classification of industrial liquid lubricants, which is equivalent to the international standard ISO3448-1992 “Industrial Liquid Lubricants-ISO Viscosity Classification”.

So, when we choose an industrial grease flow meter, we first need to consider the viscosity of the grease. Then consider the flow range and temperature. And other special requirements of users.

Our commonly used industrial grease flow meters are oval gear flow meters, turbine flow meters, and gear flow meters. There is also a mass flow meter. Next, let’s discuss separately.

Grease Flow Meters-Oval Gear

Oval gear flowmeter is a volumetric meter for continuous or intermittent measurement and control of liquid flow in a pipeline.

Oval gear flowmeter, also known as positive displacement flowmeter. A positive displacement flowmeter as a mechanical flow meter is a common type of Volumetric Flow Meter. It can measure the volume flow of high viscosity and corrosive fluids.

  • Volumetric Flow Meters
  • High measurement accuracy;
  • The installation pipeline conditions have no influence on the measurement accuracy;
  • Can be used for high-viscosity liquids;
  • Wide range;
  • The direct-reading meter can directly obtain the cumulative and total amount without external energy.
  • Clear and clear, easy to operate.

Therefore, we recommend that when the grease viscosity is high, you can first consider using an oval gear flowmeter.
Viscosity: 0.6—2mPa.s—200mPa.s—1000mPa.s-2000mPa.s.
Temperature: -20~+200℃

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Grease Flow Meters-Turbine

Turbine flow meters are velocity flow meters, also called impeller flow meters. Can be used to measure the instantaneous flow and cumulative flow of liquids and gases.

Turbine flowmeters are widely used in flow measurement: petroleum, organic liquids, inorganic liquids, liquefied gas, natural gas, coal gas, and cryogenic fluids. Turbine flowmeter signals can be divided into pulse signals or current signals (4-20mA). It is suitable for use with secondary display, PLC, DCS, and other computer control systems.

Therefore, when measuring low-viscosity oils, such as diesel, edible oil, etc., we recommend that turbine flowmeters be considered first.

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Grease Flow Meters-Gear

Gear flow meter is a micro digital positive displacement flow meter. Can measure very small flow rates and quantify small volumes of liquid. High and low-temperature resistance (-196℃-200℃).

The Gear flow meter for Microflow is made of stainless steel and is used for precise continuous or intermittent measurement of the flow or instantaneous flow of liquid. It is especially suitable for the flow measurement of heavy oil, polyvinyl alcohol, grease, and other high-viscosity media. It can measure the viscosity of Fluid up to 10000Pa.s.

  • High pressure resistance (1.0-45MPa)
  • High and low temperature resistance (-196℃-200℃)
  • Can measure various viscous media
  • High precision and repeatability
  • Pulse output/analog output optional
  • Wide range ratio (1:100)
  • Wide measuring range
  • Strong anti-corrosion and anti-fouling ability (acid and alkali)

Therefore, it is recommended to use Gear flow meters, when you need to measure grease in the following situations:High viscosity, low flow rate;Ultra-high temperatureUltra-low temperature;Small caliber;high pressure.

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Grease Flow Meters-Mass

Mass flow meter directly measures the mass flow of the medium passing through the flow meter. It can also measure the density, temperature, and viscosity of the medium

Mass flow meter is a flow measuring instrument that measures the mass flow in the pipeline. The volume of a fluid is a function of fluid temperature and pressure and is a dependent variable. The quality of a fluid is a quantity that does not change with time, space temperature, and pressure. More about: What Is Mass Flow Rate?

The mass flow meter has high accuracy. But the price is expensive. Therefore, when you need high-precision measurement, you can choose to use a mass flow meter.

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Tool: Volumetric Flow Rate & Pipe Diameter to Flow Speed Calculator

Find the most appropriate industrial grease flow meter from Sino-Inst for a variety of engineering and industrial purposes. Suitable for various fluids with different pressures and volumes. The choice of these depends on whether the volumetric or mass flow rate is to be measured. Grease flow meters offered on the site have wide minimum and maximum pressure ranges, which is considered to be a desirable quality as they can be used for a wider variety of fluids. These grease flow meters are highly accurate.

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What is Flow Meter K-factor? And how to calculate?

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What is the K-factor in a flow meter?

K-factor is a coefficient calculated by calibrating and comparing with other measuring devices that meet the accuracy requirements. The Flow Meter K-factor will be confirmed before it is put into use.

This coefficient is a fixed value. It is the actual coefficient obtained by the flowmeter manufacturer after verifying each instrument. Nothing to do with the initial design

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The flow coefficient of the flowmeter refers to the proportional relationship between the measured flow and the flow of the standard device under certain conditions. The Flow Meter K-factor is given by the manufacturer when it is calibrated.

The K value is easily immobile. Therefore, as a manufacturer, we generally set a password for the flowmeter.

Flow meter k-factors

Liquid Turbine Flow Meter is a speed-type flow meter based on the principle of torque balance.

The fluid flows through the sensor housing. Because the blades of the impeller have a certain angle with the flow direction. The impulse of the fluid makes the blades have a rotational torque. After the friction torque and fluid resistance are overcome, the blades rotate. The speed is stable after the torque is balanced.

Under certain conditions, the speed is proportional to the flow rate.

Due to the magnetic permeability of the blade, it is in the magnetic field of the signal detector (composed of permanent magnets and coils). The rotating blade cuts the magnetic lines of force. The magnetic flux of the coil is periodically changed. Electrical pulse signals are induced at both ends of the coil.

This signal is amplified and reshaped by an amplifier. A continuous rectangular pulse wave with a certain amplitude is formed. It can be transmitted to the display instrument remotely. The instantaneous flow or total amount of the fluid is displayed.

Within a certain flow range, the pulse frequency f is proportional to the instantaneous flow Q of the fluid flowing through the sensor. The flow equation is:

Where:
f——Pulse frequency [Hz]
k——The meter coefficient of the sensor [1/m3], which is given by the calibration sheet.
Q——The instantaneous flow of fluid (under working condition) [m3/h]
3600-conversion factor in seconds

The meter coefficient of each sensor is filled in the verification certificate by the manufacturer. The k value is set in the matching display instrument. The instantaneous flow and cumulative total can be displayed.

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Vortex flowmeter is a speed-type flowmeter produced according to Karman’s vortex principle,
which can be used for the measurement and measurement of conventional gas, steam and
liquid.

Vortex flow sensor has high precision and wide range ratio, no moving parts in use, which can
improve mechanical stability and reduce maintenance. Vortex flowmeter is almost not affected by the temperature, pressure, and composition of medium when measuring the volume of working conditions.

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Therefore, it is convenient to calibrate the instrument, so the vortex street flow sensor is widely used in production and life.

When a trigonal column vortex generator is set in the fluid, regular vortices are generated alternately on both sides of the vortex generator, which is called Carmen vortex.

The vortex columns are arranged asymmetrically downstream of the vortex generator. Vortex flowmeter is produced according to this principle.

Vortexes are generated by generating bodies and the number of vortexes is detected by high-sensitivity sensors. In a certain range, the number of vortexes generated is proportional to the flow rate.

In vortex flowmeter, the relationship between flow rate and the number of vortexes generated
can be expressed by the following formula：

Q：Operating volume flow of the measured medium. The unit is m3/h。
F：Frequency of the number of vortices produced by the generating body. The unit is Hz.
K：Refers to the calculated or calibrated flow coefficient. It represents how many frequency signals per cube. the coefficient is usually obtained by calibration.

The formula of standard table method calibration coefficient K:

The formula can also be used for flow correction.

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K coefficient of gear flow transmitter (flow coefficient) defines the number of impulses per L within the unit flow precisely.

The following formula is used:

Q=f×60/K

Q=Instantaneous flow L/min
F=Frequency of output impulse(HZ)
K= Coefficient of gear flow meter(impulse/min)

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K-Factors calculation

1.What is a K-factor?

Simply stated a K-factor is a dividing factor. The term is usually encountered when dealing with pulse signals although analog K-factors are sometimes used.

2. Pulse Signal K-factors

All pulse output type flow meters when they are dispatched by their manufacturer will have a calibration certificate. The calibration certificate will show that the meter has been calibrated over its flow range and noted on the certificate will be the average K-factor for the meter.

This K-factor will be given in terms of the number of pulses produced by the meter for a given volumetric flow. (e.g.) 200 pulses per U.S. gallon, 150 pulses per liter, etc.

This K-factor is the value that is entered into a batch meter or indicator/totalizer in order to give a readout in engineering units.

Example 1

If the display on a rate meter is required in U.S. gallons per second, and the K-factor of the flow meter is 210 pulses per U.S. gallon, then the K-factor entered into the rate meter would be 210.

If a totalizer associated with the same flow meter was to be set up so as to totalize in U.S. gallons the totalizer K-factor would be 210.

If the totalizer was to be set to totalize in tenths of a gallon the K-factor would be 210/10 = 21

Example 2

If the display on a rate meter is required in U.S. gallons per minute, and the K-factor of the flowmeter is 210 pulses per U.S. gallon, then the K-factor entered into the rate meter would be: 210/60 = 3.5

3.K-factors for Analog Input Signals

When batching, indication or totalization has to be carried out using an analog input signal a KEP product first converts the 4 to 20 mA signal into a 0 to 10000 Hz. signal. The K-factor is then calculated by relating the engineering unit equivalent of 20 mA to the 10000 Hz. signal.

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Example 3

A vortex meter outputs 20 mA when the flow is 2000 U.S. gallons per minute, we wish to display the rate in gallons per minute.
The rate K-factor is = 10000/2000 = 5

The value of the totalizer K-factor will depend on whether the flow rate was given in units per second, a minute, or hour and whether it is desired to totalize in whole units, tenths, hundredths, etc.

If the flow rate was given in units per second the totalizer K-factor (for whole units) is obtained by multiplying the rate K-factor by 1.

If the flow rate was given in units per minute the totalizer K-factor (for whole units) is obtained by multiplying the rate K-factor by 60.

If the flow rate was given in units per hour the totalizer K-factor (for whole units) is obtained by multiplying the rate K-factor by 3600.

The totalizer K-factor in example 3 will be = 5 x 60 = 300 in order to totalize in gallons.

If we wished to totalize in tenths of a gallon the K-factor would be 5 x 60/10 = 30

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Example 4

An electromagnetic flow meter outputs 20 mA when the flow is 20 liters per second, we wish to display the flow rate in liters per second and totalize in M³.
The rate K-factor is 10000/20 = 500
The totalizer K-factor will be 500 x 1/0.001 = 500000

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4.Multi-Point K-factors

Some flow applications dictate that multiple K-factors are used. Two applications that require multiple K-factors are:

  • flow meters with nonlinear outputs
  • wide turndown flow applications

KEP meters have an option available that allows the user to input from 3 to 16 K-factors. This multi-point K-factor option is available for both pulse and analog inputs.

5.Multi-Point K-factors for Pulse inputs

The first step is to calculate K-factors to cover each flow range. This is done by taking the information on the flow meter manufacturer’s calibration sheet and calculating the K-factors as per section 2. An alternative to using the manufacturers’ data is to conduct tests on-site against a calibrated standard.

The second step is to relate an incoming frequency range from the flow meter to a given calculated K-factor.

The final step is to program these values into the KEP instrument.

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Example 5

A turbine flow meter has the following calibration data.

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6.Multi Point K-factors for Analog Inputs

The procedure for analog inputs is essentially the same as for pulse inputs.

The first step is to calculate K-factors to cover each flow range. This is done by taking the information on the flow meter manufacturer’s calibration sheet and calculating the K-factors as per section 3. An alternative to using the manufacturer’s data is to conduct tests on site against a calibrated standard.

The second step is to relate an incoming flow value from the flow meter to a given calculated K-factor.

The final step is to program these values into the KEP instrument.

Example 6

A vortex flowmeter has the following calibration data.

Base K-factor 10000/100 = 100

Note that the point after the final one should have a flow value entered that is very much higher than the true maximum flow rate of the meter. Note also that as the last two K-factors are the same any flow above 100 gpm will be modified by a K-factor of 104. The setup is now complete.

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What is a PID controller?

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What is a PID controller?

A PID controller is an instrument used in industrial control applications to regulate temperature, flow, pressure, speed, and other process variables. PID is the abbreviation for proportional integral derivative. PID controllers use a control loop feedback mechanism to control process variables and are the most accurate and stable controllers.

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Remote Recorders

What is meant by PID?

In the manufacturing process, if the equipment or space needs to be kept at a constant temperature, then PID is the best choice.
What is meant by PID?

P: Proportion, the input deviation is multiplied by a coefficient;
I: Integral, perform an integral operation on the input deviation;
D: It is differentiation, which performs a differential operation on the input deviation.

Mathematical description of PID:
u(t)=kp[e(t)+1/TI∫e(t)dt+TD×de(t)/dt].
Where
E(t) is the error signal;
U(t) is the output signal of the controller;
kp is the ratio coefficient;
TI is the integral time constant;
TD is the derivative time constant.

PID control is a kind of negative feedback control. Because in the feedback control system, the automatic regulator and the controlled object form a closed loop.

There are two possible situations when connected into a closed-loop: positive feedback and negative feedback.

The effect of positive feedback aggravates the imbalance of the inflow and outflow of the controlled object, resulting in system instability;

Negative feedback is to alleviate the imbalance, so as to correctly achieve the purpose of automatic control.

The instrument used in PID control is a PID regulator (also called a PID controller). Simply put, the PID control algorithm determines the price of the PID regulator. The temperature controller is also a kind of control algorithm that is more suitable for temperature control PID regulator. Its control algorithm is different from the regulator control algorithm commonly used for process control such as flow and pressure.

PID Controller Working Principle

PID controller, Promotion Integration Differentiation, that is, proportional-integral-derivative controller. It is mainly through the setting of three parameters Kp, Ki, and Kd. It is used to control the basic linearity and dynamic characteristics that do not change with time.

PID controller is based on the PID control principle to adjust the deviation of the entire control system. So that the actual value of the controlled variable is consistent with the predetermined value required by the process. Different control laws are applicable to different production processes. The corresponding control law must be selected reasonably. Otherwise, the PID controller will not achieve the expected control effect.

PID controller is a kind of feedback loop component that is very common in industrial control applications. This controller compares the collected data with a reference value. This difference is then used to calculate the new input value. The purpose of this new input value is to allow the system data to reach or maintain the reference value.

The PID controller can adjust the input value based on historical data and the occurrence rate of differences. This can make the system more accurate and more stable. It can be proved by mathematical methods. When other control methods lead to system stability errors or process repetitions, a PID feedback loop can keep the system stable.

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PID Temperature Controller Working Principle

Proportional integral derivative (PID) controllers can be used as a means to control temperature, pressure, flow, and other process variables. As the name suggests, PID controllers combine proportional control with additional integral and derivative adjustments. Help the equipment to automatically compensate for changes in the system.

Computer-controlled thermostat: Using PID fuzzy control technology* Use advanced digital technology to form a fuzzy control to solve the problem of inertial temperature error through the combination of Pvar, Ivar, and Dvar (proportional, integral, derivative).

Many manufacturers often encounter the problem of inertial temperature error in the process of using the thermostat. Suffering cannot be solved, relying on manual pressure adjustment to control the temperature.

PID controller Applications

The PID controller is the most widely used controller. There are many digital pid algorithms.
PID controllers are mostly used for temperature control. But there are other more advanced and lower-level programs.

The PID regulator used by the instrument ranges from tens of yuan to tens of thousands of yuan. The difference lies in IO precision, type, algorithm complexity, operation speed, and additional functions.

The PID algorithm used by PLC is also different. Usually simpler than meters.

In the field of temperature control, there are PID meters, smart fuzzy meters, fuzzy PID meters, and even industrial computers.

If the temperature control also needs to control the temperature rise curve, then a simple PID meter is not suitable. A set value generator is also needed, and most intelligent thermostats with this function are built-in.

  1. Classic PID control algorithm regulator

For example, the accuracy is 0.5%. The intelligent regulator is used for process control such as pressure, flow, and liquid level to achieve good control effects. The temperature control effect is not good when used for temperature control.

  1. Fuzzy control algorithm regulator

Such as accuracy of 0.3%. The fuzzy PID regulator is used for pressure, flow, liquid level, and other process control effects. It is best for temperature control in plastic/food/packaging machinery, heating furnaces, and other industries with a constant temperature effect of ±1℃. PID parameter self-tuning effect is excellent It is the classic PID control algorithm regulator. The price of the two is the same.

  1. Artificial intelligence control algorithm regulator

Such as an accuracy of 0.2%. This artificial intelligence regulator is suitable for all automatic control sites and can achieve very good control effects. The best constant temperature effect for temperature control is ±0.1℃. The effect of PID parameter self-tuning is better than the adjustment of classic PID control algorithms and fuzzy control algorithms The price is slightly higher. Product performance is no different from European and American products.

  1. Temperature controller

Such as an accuracy of 0.2%. The temperature controller is dedicated to the temperature control of various large lag working conditions (such as kilns, electric furnaces). The temperature is constant and does not fluctuate. The performance is not much different from that of Japanese island power products. The cost is lower.

Related measurement and control instruments

You may like:

Sino-Inst offers over 10 PID controllers for Industrial data recording and analysis.

It is widely used in hydropower, tap water, petroleum, chemical, machinery, hydraulic and other industries to measure, display and control the pressure of fluid media on site.

A wide variety of PID controllers are available to you, such as free samples, paid samples.

Sino-Inst is a globally recognized supplier and manufacturer of PID controllers, located in China.

What is a pressure sensor?

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What is a pressure sensor?

A pressure sensor is a device that senses a pressure signal and converts the pressure signal into a usable output electrical signal according to certain rules.

Pressure sensors have a variety of structural types. Common types are strain gauge, piezoresistive, capacitive, piezoelectric, vibration frequency pressure sensors.

Pressure sensors are mainly used in booster cylinders. Pneumatic-hydraulic booster cylinder. Gas-hydraulic booster. Air conditioning and refrigeration equipment and other fields.

Get a Quote More Pressure Sensors

Types of pressure sensors

Pressure sensors can be classified according to the pressure range they measure, their operating temperature range or the type of pressure they measure. In terms of pressure type, pressure sensors can be divided into several major categories.

Absolute pressure sensors

Absolute pressure sensors measure pressure relative to an ideal vacuum pressure (0 PS or no pressure). With reference to vacuum, the atmospheric pressure at sea level is 101.325 kPa (14.7PSI).

Gauge Pressure Sensors

Gauge pressure sensors are used in different applications because they can be calibrated to measure pressure relative to a given atmospheric pressure at a given location. A tire pressure gauge is an example of a gauge pressure indication. More about: What is Diaphragm pressure gauge?

Vacuum Pressure Sensors

Vacuum pressure sensors are used to measure pressures that are less than atmospheric pressure at a given location.

Differential Pressure Sensor

A differential pressure sensor or transmitter measures the difference between two or more pressures introduced as inputs to a sensing unit. An example is the measurement of the pressure drop across an oil filter. Differential pressure is also used to measure the flow or level in a pressurized vessel.

Sealed Pressure Sensors

Extended reading: Featured Diaphragm Seal Pressure Transmitters

A sealed pressure transducer is similar to a gauge pressure transducer, except that it has been calibrated by the manufacturer to measure pressure relative to sea level pressure.

More about Industrial Pressure Sensors

Featured Pressure Sensors

SI-503K Gas Pressure Sensor
SI-702 High Pressure Sensor
SI-702S Ultra-High Pressure Senors
SI-512H High Temperature Pressure Sensor
High Frequency Dynamic Pressure Sensor
SI-706 Combined Pressure and Temperature Sensor-Dual function
SI-338 Ceramic Pressure Sensor
Absolute Pressure Transmitter
Hydrostatic pressure transmitter
Diaphragm Seal Pressure Transmitter
Diffused silicon Gauge Pressure Transmitter
Cryogenic Pressure Transducer

Working Principles of Pressure Sensors

Pressure Sensors are devices that convert various pressures into another physical quantity (usually electricity) that can be easily processed and transmitted according to certain rules. pressure sensors generally consist of three parts: a sensitive element, a conversion element and a measurement circuit, sometimes with an additional auxiliary power supply.

Extended Reading: Digital Pressure Sensor-RS485

Let’s look at the technology used in pressure sensors in more detail.

Pressure measurement technologies

Strain gauge pressure sensors are sensors that measure pressure indirectly by measuring the strain of various elastic elements. Depending on the material used to make them, strain gages can be divided into two categories: metal and semiconductor. The operating principle of strain gauge elements is based on the “strain effect” of conductors and semiconductors. This means that the resistance of conductors and semiconductors changes when they are mechanically deformed.

When a metal wire is subjected to an external force, its length and cross-sectional area will change. The resistance value will be changed. If the wire is elongated by an external force, its length increases. When the cross-sectional area is reduced, the resistance value increases.

When the wire is compressed by an external force, the length decreases and the cross-section increases, the resistance value decreases.

The strain on the wire can be obtained by measuring the change in voltage across the resistance.

Extended Reading: Resistive Pressure Transducer

A piezoresistive pressure sensor is a sensor made by using the piezoresistive effect of single-crystal silicon material and integrated circuit technology. The resistivity of single-crystal silicon material changes when it is subjected to a force, and an electrical signal output proportional to the change in force is obtained through the measurement circuit. It is also called diffusion silicon piezoresistive pressure sensor, which is different from the paste type strain gauge that needs to feel the external force indirectly through the elastic sensitive element, but directly through the silicon diaphragm to feel the measured pressure.

Piezoresistive pressure sensors are mainly based on the piezoresistive effect. The piezoresistive effect is used to describe the change in resistance of a material when subjected to mechanical stress. Unlike the piezoelectric effect, the piezoresistive effect only produces a change in impedance and does not produce an electrical charge.

Extended reading: Silicon Pressure Sensor

Capacitive pressure sensor is a pressure sensor that uses capacitance as a sensitive element to convert the measured pressure into a change in capacitance value. This kind of pressure sensor generally uses a round metal film or metal-plated film as an electrode of the capacitor, when the film feels the pressure and deformation, the electric capacity formed between the film and the fixed electrode changes, through the measurement circuit can output a certain relationship with the voltage of the electrical signal. The capacitive pressure sensor belongs to the class of

The capacitive pressure sensor belongs to the pole pitch change type capacitive sensor, which can be divided into a single capacitance pressure sensor and a differential capacitance pressure sensor.

Extended Reading: Smart pressure transmitter working principle

The piezoelectric pressure sensor is mainly based on the piezoelectric effect (Piezoelectric effect), using electrical components and other machinery to convert the pressure to be measured into electricity. Then the relevant measurement work measurement precision instrument. For example, many pressure transmitters and pressure sensors.

Piezoelectric sensors cannot be used in static measurements. The reason for this is that the charge can be saved only when the circuit has an infinite input resistance after an external force is applied. However, this is not the case in practice.

Therefore, piezoelectric sensors can only be used for dynamic measurements. The main piezoelectric materials are amine dihydrogen phosphate, sodium potassium tartrate, and quartz. It is in quartz that the piezoelectric effect is found.

Extended Reading: Electronic Pressure Switch for Air Compressor

Electromagnetic pressure sensors are a variety of sensors that use the electromagnetic principle collectively, mainly including inductive pressure sensors, Hall pressure sensors, eddy current pressure sensors, etc.

Inductive pressure sensors work due to different magnetic materials and magnetic permeability. When pressure is applied to the diaphragm, the size of the air gap changes. The change in air gap affects the change in inductance of the coil. The processing circuit can convert this change in inductance into a corresponding signal output for the purpose of measuring pressure.

This type of pressure sensor can be divided into two types according to the magnetic circuit change: variable reluctance and variable permeability. The advantages of inductive pressure sensors are high sensitivity and large measurement range; the disadvantage is that they cannot be applied to high-frequency dynamic environments.

Extended Reading: MEMS Pressure Sensors

Hall pressure sensors are made based on the Hall effect of certain semiconductor materials.

The Hall effect is the phenomenon that when a solid conductor is placed within a magnetic field and a current is passed through it, the charge carriers within the conductor are deflected to one side by the Lorentz force, which then generates a voltage (Hall voltage). The electric field force induced by the voltage balances the Lorentz force.

The polarity of the Hall voltage confirms that the current inside the conductor is caused by the movement of negatively charged particles (free electrons).

Pressure sensors based on the eddy current effect. The eddy current effect is produced by a moving magnetic field intersecting a metallic conductor or by a moving metallic conductor meeting perpendicular to the magnetic field. In short, it is caused by the electromagnetic induction effect. This action produces a current that circulates in the conductor.

The eddy current characteristic makes eddy current detection have characteristics such as zero frequency response, so eddy current pressure sensors can be used for static force detection.

Vibro pressure sensors are frequency-sensitive sensors, and this frequency measurement has a very high degree of accuracy. Because time and frequency are the physical parameters that can be measured accurately. And the frequency signal in the transmission process can ignore the influence of cable resistance, inductance, capacitance, and other factors.

At the same time, the Vibro-sinusoidal pressure sensor also has strong anti-interference ability, small zero-point drift, good temperature characteristics, simple structure, high resolution, stable performance, easy data transmission, processing, and storage. It is easy to realize the digitalization of the instrument. Therefore, the vibrating-sine type pressure sensor can also be used as one of the directions of sensing technology development.

Extended reading: Best Price Ceramic Pressure Sensor

Extended reading: Pressure indicator transmitters

Pressure sensors, pressure transducers, and pressure transmitters

A pressure sensor is a device or device that can sense a pressure signal and convert the pressure signal into a usable output electrical signal according to a certain rule.
A pressure sensor usually consists of a pressure-sensitive element and a signal processing unit. According to different test pressure types, pressure sensors can be divided into gauge pressure sensors, differential pressure sensors and absolute pressure sensors. A pressure sensor is the core part of pressure transmitter.

In a pressure transducer, a thin-film or piezo-resistive pressure sensor is mounted on a process connection. The transducer converts pressure into an analog electronic output signal, typically as a millivolt per volt output. These signals are not linearized or temperature compensated.

A pressure transmitter has additional circuitry that linearizes, compensates, and amplifies the signal from a transducer. The different signal types are typically voltage signals (eg, 0 to 5 or 0 to 10 volts), milliamp (eg, 4 to 20 milliamp), or digital. The instrument can transmit the signal to a remote receiver.

Extended reading: Static pressure vs dynamic pressure vs total pressure

Pressure sensor performance parameters

Pressure sensors mainly have the following parameters.

1.Capacity.

The range refers to the rated load of the pressure sensor. The general unit is KGf, N, etc.. Such as the range of 100KGf, the sensor measurement range is 0-100KGf.

2. Rated output.

Sensitivity is the output signal coefficient of the pressure sensor, the unit is mV / V, common 1mV / V, 2mV / V, the full range of the pressure sensor output = working voltage * sensitivity, for example: working voltage 5VDC, sensitivity 2mV / V, the full range of output that is 5V * 2mV / V = 10mV, such as pressure sensors full range of 100KG, pressure full 100KG, the output that is 10mV, pressure 50KG that is 5mV.

3. Non-linearity.

Non-linearity is the percentage of the maximum deviation between the output value of the empty load and the output value of the rated load determined by the straight line and the actual measured curve of the increased load for the rated output value. In theory, the output of the sensor should be linear, but in fact it is not. Non-linearity is the percentage deviation from the ideal. Non-linear units: %FS, non-linear error = range * non-linearity, such as the range of 100KG, non-linearity of 0.05% FS, non-linear error that is: 100KG * 0.05% = 0.05KG.

4. Repeat ability.

Repeatability error refers to the repeated loading of the sensor to the rated load and unloading under the same environmental conditions. The maximum difference of the output value on the same load point during the loading process on the percentage of rated output.

5.Creep.

Creep refers to the load remains unchanged, other test conditions also remain unchanged, the pressure sensor output change over time on the percentage of rated output, generally taken 30min.

6.Hysteresis.

Hysteresis refers to the pressure sensor from no load gradually loaded to the rated load and then gradually unloaded. In the same load point on the maximum difference between the loaded and unloaded output on the rated output value of the percentage.

7. Zero balance.

Under the recommended voltage excitation, the output value of the pressure sensor at no load is a percentage of the rated output. Theoretically, the output of the pressure sensor at no load should be zero, in fact, the output of the pressure sensor at no load is not zero, which there is a deviation, zero output is the percentage of deviation.

8.Input resistance.

Input resistance is the signal output open circuit, the sensor is not pressurized, from the pressure sensor input (Cang positive pressure sensor for the red and black line) measured impedance value.

9.Output resistance.

Output resistance is a short circuit at the input of the pressure sensor, the sensor is not pressurized, the impedance measured from the signal output (Cangzhou pressure sensor for the green and white lines).

10.Insulation impedance.

Insulation impedance is the DC impedance value between the circuit of the pressure sensor and the elastomer.

11.Operation Temp range.

Operating temperature range refers to the pressure sensor in the temperature range of its performance parameters will not produce permanent harmful changes.

12. Compensated temp range.

Temperature compensation range refers to the temperature range, the rated output of the sensor and zero balance are closely compensated, so as not to exceed the specified range.

13. Temperature effect on zero.

Temperature effect on zero refers to the effect of changes in ambient temperature on the zero point of the pressure sensor. Generally used for every 10 ℃ change in temperature, the amount of change in zero balance caused by the percentage of the rated output to express, the unit: % F.S./10 ℃.

14. Temperature effect on out.

Sensitivity temperature drift is the change in the sensitivity of the pressure sensor caused by changes in ambient temperature. Generally expressed as a percentage of the rated output for each 10 ℃ change in temperature caused by the change in sensitivity, the unit is: F.S./10 ℃.

15. Safe Load Limit.

Safe overload means that the load will not cause destructive damage to the pressure sensor, but can not be overloaded for a long time.

16. Ultimate overload.

Ultimate overload is the limit value of the pressure sensor load.

17. Excitation voltage Excitation recommend.

Excitation voltage refers to the working voltage of the pressure sensor, generally 5-12VDC.

Extended Reading: Up to 800°C High Temperature Pressure Sensor

Applications of Pressure Sensors

Pressure sensor is one of the most commonly used sensors in industrial practice. It is widely used in various industrial self-control environments. It involves water conservancy and hydropower, railroad transportation, intelligent building, production automation, aerospace, military, petrochemical, oil well, electric power, ship, machine tool, pipeline and many other industries.

The following is a brief introduction to some application examples of pressure sensors.

  1. Application to hydraulic system

Pressure sensor in the hydraulic system is mainly to complete the closed-loop control of the force. When the control valve spool moves suddenly, a spike pressure of several times the working pressure of the system will be formed in a very short period of time.

  1. Pressure sensors in the application of water treatment

China’s environmental protection water treatment industry, in recent years, has been rapid development, and the future prospects are promising. Water and wastewater treatment processes rely on the use of pressure sensors to provide an important means of control and monitoring for system protection and quality assurance.

  1. Application in injection molding

Pressure sensors have an important role in injection molds. Pressure sensors can be installed in the nozzles of injection molding machines, hot runner systems, cold runner systems and mold cavities to measure the plastic pressure somewhere between the nozzle of the injection molding machine and the mold cavity during the injection, filling, holding and cooling processes.

  1. Applications in compressors, air conditioning and cooling equipment

Pressure sensors are commonly used in air compressors and air conditioning and refrigeration equipment. These sensors are compact and easy to install, and the pressure guide port is usually designed with a special valve needle.

  1. Used in monitoring mine pressure

Sensor technology as one of the key technologies for mine pressure monitoring.

On the one hand, we should properly apply the existing variety of sensors to serve the mining industry;

On the other hand, sensor manufacturers develop and develop new pressure sensors to adapt to more mining industry applications.

Note that the pressure transmitter needs to be calibrated after a period of use. In order to ensure the accuracy of the quantity.

FAQ

A proximity sensor is a device that has the ability to sense the proximity of an object… It uses the sensitivity of the displacement sensor to the approaching object to identify the proximity of the object. And output the corresponding switch signal. Therefore, the proximity sensor is often referred to as a proximity switch.

It is a general term for a sensor that replaces a contact detection method such as a switch for the purpose of detecting an object without touching it. It detects the movement and presence of the object and converts it into an electrical signal.

Proximity sensor, also known as contactless proximity sensor, is the ideal electronic sensor quantity proximity sensor.

When the metal detection body close to the sensor sensing area. The sensor can be no contact, no pressure, no spark, rapid electrical command. Accurate response to the position and travel of the motion mechanism. Even for general travel control, the positioning accuracy, operating frequency, service life, ease of installation and adjustment, and the ability to adapt to harsh environments are incomparable to those of general mechanical travel sensors. It is widely used in machine tool, metallurgy, chemical, light textile and printing industries.

Translated with www.DeepL.com/Translator (free version)

A differential pressure sensor is a sensor used to measure the difference between two pressures, usually at the front and rear ends of a piece of equipment or component.

Extended reading: Differential Pressure Transmitter Installation Guide

Oil pressure sensor is a device that converts pressure signals into electrical signals through the piezoresistive effect.

Oil pressure sensor is one of the most commonly used sensors in industry. It is widely used in various industrial automatic control environments, involving water conservancy and hydropower, engineering machinery, aerospace, transportation, petrochemical, machine tools, pipelines and many other industries.

Extended reading: High Pressure Hydraulic Flow Meter

As an important part of hydraulic equipment, the pressure sensor is used for pressure measurement and control. It can accurately measure the pressure to be measured and transmit the test results to the subsequent display or control in a timely manner.

Extended reading: Miniature Pressure Switch

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What is a pressure sensor? and other questions about pressure sensors. We hope that after reading this article, you will have a clear understanding.

Sino-Inst offers over 20 Pressure sensors. A wide variety of Pressure sensors options are available to you. Such as free samples, paid samples.

Sino-Inst is a globally recognized manufacturer of Pressure sensors, located in China. Sino-Inst sells through a mature distribution network that reaches all 30 countries worldwide. Pressure sensors products are most popular in Europe, Southeast Asia, and Mid East. You can ensure product safety by selecting from certified suppliers. With ISO9001, ISO14001 certification.

Water depth sensor- Water level sensor Solutions

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How do you measure the depth of water?

Water depth sensors are also known as water level sensors. Water depth sensors are often used to measure tank levels, well depths, river depths, etc. There are many different types of water depth sensors. All of them are used to measure the water level by submerging underwater or above the water surface. Then, they are converted into a water depth or water level signal. For example, submersible hydrostatic level meter, ultrasonic level meter, etc.

RFQ More level sensors

At present, the common measurement principle of liquid level meter in the industry involves mechanics, thermal, electrical, optical, and other aspects. The product models even reach hundreds of kinds. Of course, different types of level meters mean that they are produced, used, and calibrated in different ways. It is not possible to fit all measurement environments.

Water Depth/Level Sensors Types

The following will be from the perspective of the measurement method, for the current market more than ten kinds of liquid level meter classification. To help users in the selection of products to make the appropriate choice.

Water Depth Sensors measured by buoyancy

The buoyancy type level meter has a float (float ball or float). The float is in equilibrium on the static liquid level. When the liquid level changes, the float is displaced with the liquid level. The electronic component acquires the float displacement in a certain way. And then converted to the liquid level change.

Due to the different ways of receiving float displacement by electronic components, the buoyancy method liquid level meter is divided into magnetic flap level meter, float level meter, magnetostrictive level meter, etc.

Magnetic level meter consists of magnetic float, cylindrical container, scale and transmitter.

The float moves with the liquid level in the container, and the magnetic field of the float acts on the sensor. The sensor is a strip of rubber-sealed in a stainless steel tube of equal length to the measured liquid level. There are numerous reed switches welded to it at intervals of 1cm or less.

When the reed switch is at the same level as the float, it closes. Otherwise, the transmitter receives the current signal generated by the amount of resistance connected to the reed switch, which is converted to the liquid level.

Float movement is shown on the scale as a red and white bead flip, indicating the liquid level.

Extended reading: Water Tank Level Controller

Float level meter has a float, spring, magnetic steel chamber and indicator, designed according to Archimedes’ law and magnetic coupling principle.

The displacement of the float causes the magnetic field of the magnet chamber to change. The magnetic sensor inside the indicator precisely measures the change of the surrounding magnetic field.

Float Level Sensors – Single and Multipoint

The magnetostrictive level meter is mainly composed of float, waveguide, and transmitter.

The electronic component of the transmitter generates a low-voltage current pulse, which starts timing and generates a magnetic field that propagates down the magnetostrictive line.

The float moves along the measuring rod as the level changes, and the magnet inside the float also generates a magnetic field. When the two magnetic fields meet, the magnetostrictive lines are twisted to form a torsional stress wave pulse. The velocity of the pulse is known, and the pulse propagation time is calculated to correspond to the exact change in the liquid level.

Magnetostrictive Level Transmitters

Extended reading: Magnetostrictive Hydraulic Cylinder Position Sensor

Liquid level meter measured by pressure

The level meter of pressure method is the level meter that reflects the liquid level by measuring the liquid pressure through its pressure measuring element. It is generally composed of transmitter, sensor and pressure probe. The sensor is a special metal rod or cable with a built-in capillary hose, and the probe is constructed as a stainless steel cylinder core with a diaphragm at the bottom.

The probe intrudes into the liquid and tests the difference between the static pressure of the liquid and the actual atmospheric pressure, which varies with the liquid level. The electronic components receive the differential pressure signal to reflect the change in liquid level. According to the different materials of sensors are divided into two types of rod and cable type.

Rod type pressure level meter sensor is a metal rod. Its general technical parameters are, the measurement range is generally 0 ~ 5m, output signal: (4 ~ 20) mA, measurement accuracy is generally ± 0.5%.

SMT3151TR Submersible Level Transmitter
Hydrostatic level transmitter is also called hydrostatic level gauge. The rod-type Hydrostatic level transmitter 4-20mADC standard signal output. Flange or threaded installation. Can withstand high temperatures up to 450 ℃.

Because the sensor is a cable, can be bent, convenient handling and loading, so the range of the cable type pressure level meter can be very large, there are 100m, or even 300m, its measurement accuracy is generally ± 1.0%.

SI-151 Hydrostatic Level Sensor
Hydrostatic Level Sensor (Best Price), also called Hydrostatic level transmitter. Continuous level measurement in liquid applications with pressure sensors.

Differential pressure level meter is also through the detection of pressure differences to measure the liquid level.

The level meter has two pressure-taking ports in the gas phase and liquid phase.

The pressure at the gas phase pressure point is the pressure of the gas phase in the equipment. The pressure at the liquid phase pressure point is not only affected by the gas phase pressure, but also by the static pressure of the liquid column.

The difference between the liquid phase and gas phase pressure is the static pressure generated by the liquid column, which is converted into the liquid surface height.

Flange Mounted Differential Pressure Transmitter
Extended Diaphragm Seal DP Level Transmitter
Remote Seal Differential Pressure Transmitter
Differential pressure(DP) level transmitter

Liquid level meter measured by reflection

At present, there are two main types of reflective level meters: radar level meter and ultrasonic level meter. Their principles are basically the same, they are through the emission – reflection – reception of ultrasonic or electromagnetic wave (radar wave) way to measure the liquid level height.

Radar level measurement uses Non-contacting radar technology for Continuous level measurement. Liquids and solids are commonly measured with this measuring technique.

Radar level transmitters use radar technology to perform non-contact continuous level measurement. The radar level indicator converts the level into an electrical signal. The level signal output can then be utilised by other instrumentation to monitor or control. Liquids and solids are commonly measured with this measuring technique. Like: Fly ash silo. Radar level sensors are divided into: Pulsed radar technology and frequency modulated continuous wave (FMCW) radar level sensors.

Sino-Inst produces a 120GHz FMCW radar level sensor, 26GHz radar level meter, 6GHz level meter.

Extended reading: Radar Level Meter for Corrosive Liquids

Extended reading: Radar Water Level Sensor Applications

Ultrasonic Level Sensing sensors and transmitters are used for continuous, non-contact level measurement.

Ultrasonic Level Sensing is a low-cost liquid level measurement technology. Ultrasonic Level Sensing sensors and transmitters are used for tank or river level measurement. Ultrasonic Level Sensing does not need to contact the medium, can be continuously measured at low cost. Therefore, Ultrasonic Level Sensing is very popular among users. Ultrasonic liquid level sensors are available in general and intrinsically safe types. Output 4~20mA standard signal or output the measurement result to the secondary meter through RS-485. Meets the system’s automatic control.

Extended Reading: Wireless Water Meter

Liquid level meter through the conductive method of measurement

Level meters in the conductive mode are based on the electrical principle. The level is measured by means of measuring capacitance or resistance. This type of level meter mainly includes capacitance level meter, radio frequency conductivity level meter, resistance level meter.

The Capacitance level meter uses the change of measuring capacitance to measure the level of the liquid.

By a metal rod inserted into the liquid container, the metal rod is a pole of capacitance, the container wall is the other pole of capacitance. The medium between the two electrodes is the liquid and the gas above it.

As the dielectric constant of the liquid and the dielectric constant of the gas on the liquid surface is different, the level of the liquid is measured by the change of the capacitance between the two electrodes.

Extended reading: Capacitive water level sensor

RF conductivity level meter is an upgraded version of capacitance level meter, which can be understood as measuring conductivity with high frequency radio waves.

When the instrument works, the sensor of the instrument and the filling wall, and the measured medium form the conductivity value. When the level changes, the conductance value changes accordingly. The circuit unit converts the measured conductance value into a level signal output. To achieve the level measurement.

Extended reading: Radar Non Contact Water Level Sensor

Deep Well Water Level Sensor

Deep Well water level sensor is to apply Hydrostatic Level Sensor to deep well. The Well water level sensor submerged in deep well works together with a submersible water pump. The range within 300m ～ 1000m.

Deep Wells Water level sensor is based on the principle that the measured liquid pressure is proportional to the height of the liquid. The piezoresistive effect of the advanced foreign isolated silicon diffused sensor is used. Change to electrical signal. After temperature compensation and linear correction, convert to 4-20mA standard electrical signal. Well water level sensor submerged in deep well work together with water pump. It is extremely difficult to replace and submit an inspection. Therefore, it adopts stainless steel cable, waterproof, sealing ring, and other four-level seals. Special cables and special water sealing technology make the transmitter highly reliable and stable.

Extended Reading: 3 inch (3″) Water Flow Meter

Portable Ultrasonic Water Depth Gauge

Water Depth Gauge is a portable water depth detector based on the principle of ultrasound. Ideal water depth measuring instrument for ships, oceans, reservoirs, lakes, rivers, and shallow water level monitoring.

Water Depth Gauge is a necessary instrument to measure water depth in reservoir, lake, river, shallow sear. Place ultrasonic transducer on water surface or into a certain position into water. The device can caculate current water depth. HS-SFCC Portable Ultrasonic Water Depth Gauge It has perfect water depth measurement function. Control function, data transmission function and man-machine communication function. This machine integrates ultrasonic transceiver sensor, servo circuit, temperature compensation sensor and compensation circuit unit, display, control signal output and serial data or analog output unit (optional) as a water depth measuring instrument. It has the characteristics of low maintenance, high reliability, long life, convenient use, simple operation and accurate measurement. Therefore, it is widely used in water area monitoring.

Read more about: Common River Water Level Measurement Methods

How do you measure water level in tank with sensor?

The Water Tank Level Sensor is an important part of the water tank level control system. Using a level sensor for the water tank, solenoid valve, control box, liquid level switch and other accessories can effectively form a Water Tank Level control system. Monitor the materials stored in the water tank. Master important data such as its liquid level, reserves, and quality. A reasonable liquid level can ensure the safe, reliable, and efficient operation of the storage tank.

Read more about: Water Tank Level Sensors for Level Control

More Level Measurement Solutions

Sino-Inst offers over 20 Water depth sensors for level measurement.

About 50% of these are liquid level meters, 40% is the tank level sensor.

A wide variety of Water depth sensors options are available to you, such as free samples, paid samples.

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

How to Select Ultrasonic flow detectors?

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What is an ultrasonic flow detector?

An ultrasonic flow detector is often understood as an ultrasonic flow meter or ultrasonic transducer. In fact, an Ultrasonic flow detector refers to the probe part of the ultrasonic flow meter or sensor part. Ultrasonic flow detectors can be equipped with different ultrasonic flow detectors to meet different measurement needs. For example, a portable ultrasonic flowmeter can be equipped with a clamp Ultrasonic flow detector. commonly used in water, oil, and other single liquid flow rate detection.

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Ultrasonic flow detectors types

Ultrasonic flow detectors can be divided into external paste type, insertion type, and pipe section type according to the installation method.

A) Clamp-on type

External paste type ultrasonic flowmeter is produced earlier, the user is more familiar with and more widely used ultrasonic flowmeter. Installation of the transducer without pipeline disconnection. That is posted that use, it fully embodies the ultrasonic flowmeter installation is simple, easy to use characteristics.

Extended reading: Portable ultrasonic flow meter for water

B）Pipe section type

Certain pipelines due to material sparse, poor sound conduction, rust and corrosion is serious. Lining and pipeline space with gaps and other reasons. Resulting in serious ultrasonic signal attenuation. Ultrasonic flowmeter with external paste type can not be measured normally. Generated the pipe segment ultrasonic flowmeter.

Pipe segment ultrasonic flowmeter to the converter and measuring tube composition as a whole, to solve the external paste flowmeter measurement in a problem. Measurement accuracy is also higher than other ultrasonic flowmeter. But at the same time also sacrificed the advantages of the external paste type ultrasonic flowmeter non-flow installation. Requires the installation of the transducer to cut the pipe.

Extended Reading: Inline Ultrasonic Flow Meter

C) Insertion type

Insertion type ultrasonic flowmeter in between the above two. Installation can be non-stop flow, the use of special tools have water pipes on the hole, the transducer into the pipe, complete the installation. Transducer pipeline, its signal emission, receiving only the measured medium. Its measurement is not limited by the pipe quality and pipe lining materials.

TM series standard clamp-on Ultrasonic flow detectors

  • With a strong magnet, when measuring steel and cast iron pipes, the sensor only needs to be adsorbed on the outer wall of the pipe.
  • Equipped with a ground terminal, can be used in the occasion of strong electromagnetic interference.
  • Can be fixed by a steel belt, steel wire rope, tensioning belt, special clamps.
  • The upper cover of the sensor is marked with the direction of ultrasonic signal emission.
  • The protection level can reach IP68 after the junction box is filled with glue.
  • Complete specifications, divided into large, medium, and small models, measuring pipe diameter range: DN15~DN6000mm.
  • Temperature range: -40~90℃.
  • According to the different uses, the standard clamp-on sensors are divided into two categories: portable and stationary.

1 Tensioning belt fastening groove
2 Wire rope fastening groove
3 Steel belt fastening slot
4 Top cover fastening screw
5 Signal emission direction indication arrow
6 Sound wedge
7 Powerful magnets
8 Anti-slip groove

9 Upstream and downstream sign sticker
10 Cable interface
11 Installation distance measurement starting and ending points
12 Product information label
13 Positive terminal block
14 Negative terminal block
15 Ground terminal block
16 Junction box

Clamp-on Ultrasonic Flow Meter Working Principle

Clamp on Ultrasonic Flow Meter adopts the measurement principle of time difference method. It uses the ultrasonic wave emitted by the sensor to propagate in the flowing fluid. The sound wave propagation speed in the downstream direction will increase, and the backward direction will decrease. In the same propagation distance, there will be different transmission times. According to the difference between the transmission time and the measured The relationship between fluid velocity measures the fluid velocity.

The flow rate of the fluid is different in different positions in the tube. The flow rate in the center of the tube is faster than the flow rate near the wall of the tube. The flow velocity distribution of the fluid in the pipeline can be represented by the flow velocity cross-sectional distribution diagram.

By setting the flowmeter and considering the cross-sectional distribution of the flow velocity, the average flow velocity can be calculated. Then the volume flow of the fluid can be obtained according to the cross-sectional area of the pipe.

Notes:
V measure fluid velocity
M ultrasonic reflection times
D pipe diameter
θ The angle between the ultrasonic signal and the fluid
T up The time when the downstream sensor transmits the signal to the upstream
T down Time from upstream sensor to downstream
ΔT = T up – T down

Guess You’ll Like: Ultrasonic flow meters types & technical guide

HT series high temperature clamp-on ultrasonic flowmeter sensor

  • With high temperature resistant powerful magnet, when measuring steel and cast iron pipes, the sensor only needs to be adsorbed on the outer wall of the pipe.
  • Equipped with ground terminal, can be used in the occasion of strong electromagnetic interference.
  • Can be fixed by steel belt, steel wire rope, tensioning belt, special clamps.
  • The upper cover of the sensor is marked with the direction of ultrasonic signal emission.
  • The protection level can reach IP68 after the junction box is filled with glue.
  • Complete specifications, divided into large, medium and small specifications, measuring pipe diameter range: DN15~DN6000mm,
  • Temperature range: -40~160℃.
  • According to the different uses, high temperature clamp-on sensors are divided into two categories: portable and fixed.

1 Tensioning belt fastening groove
2 Wire rope fastening groove
3 Steel belt fastening slot
4 Top cover fastening screw
5 Signal emission direction indication arrow
6 Sound wedge
7 Powerful magnets
8 Anti-slip groove

9 Upstream and downstream sign sticker
10 Cable interface
11 Installation distance measurement starting and ending points
12 Product information label
13 Positive terminal block
14 Negative terminal block
15 Ground terminal block
16 Junction box

Extended reading: Flow Totalizer F3000X for Data collection and calculation

Other commonly used ultrasonic flow detectors:

What Does an Ultrasonic Doppler Flow Detector Measure?

From the ultrasonic measurement principle, the time difference method is suitable for measuring pure and less impurity liquids. Such as tap water, river seawater, sewage treatment plant effluent, etc. The Doppler method is suitable for measuring liquids and slurries with a high impurity content. Such as urban drainage, mud, pulp and so on.

Judging from the company’s years of practical experience, the two measurement methods are relatively vague for the quantitative indicators of the impurity content of the measured medium. The main reason is that there is currently no effective instrumentation for measuring the impurity content of liquids.

Doppler ultrasonic flowmeter flow rate measurement is based on the Doppler effect. The probe emits a beam of ultrasonic waves obliquely upward. Ultrasound propagates in fluids. The fluid will contain impurities such as bubbles or particles (it can be considered that the impurities in the fluid are at the same speed as the water flow).

When the ultrasonic wave contacts the impurities in the fluid, the reflected ultrasonic wave will produce a Doppler frequency shift Δf. The Doppler shift Δf is proportional to the flow velocity. The flow velocity of the fluid can be measured by measuring the Doppler frequency shift Δf.

The Dopp ultrasonic flowmeter uses the velocity area method to measure the flow. The flow velocity V is measured using an ultrasonic flow velocity sensor. Use a pressure water level gauge to measure the water level H. The channel parameters set in the controller in advance. The controller can use the water level to automatically convert the flow area S. The formula for the flow rate of the fluid is:

Q= V×S

Wherein V- – – -flow velocity S- – – -flow area Q- – -instantaneous flow

Since the velocity area method is used to measure the flow, it can be applied to any shape of the section.

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FAQ

Ultrasonic flowmeter refers to a flowmeter developed based on the principle that the propagation velocity of ultrasonic waves in the flow medium is equal to the average flow velocity of the measured medium and the vector sum of the velocity of the sound waves in the stationary medium.

According to the principle of signal detection, ultrasonic flowmeter can be divided into propagation speed difference method (direct time difference method, time difference method, phase difference method and frequency difference method), beam shift method, Doppler method, mutual correlation method, spatial filtering method and noise method, etc.

Our time difference ultrasonic flowmeter: measuring the time difference caused by the difference in propagation velocity when propagating downstream and upstream to calculate the measured fluid velocity.

The measurement accuracy of the ultrasonic flowmeter is very high. Almost no interference from various parameters of the measured medium.

Sino-Inst manufactures and supplies ultrasonic flow meters with an accuracy of 1%. This accuracy can meet the measurement needs of most customers.

In particular, it can solve the flow measurement problems of strong corrosive, non-conductive, radioactive and flammable and explosive media that other instruments cannot.

So what causes the inaccurate measurement of the ultrasonic flowmeter?

The following are the reasons for the inaccurate measurement:
The influence of pipeline parameter equipment on the accuracy of ultrasonic flowmeter measurement.
The influence of upstream and downstream straight pipes on the accuracy of ultrasonic flowmeter measurement.
The influence of couplant on measurement accuracy.
The influence of the installation position of the ultrasonic flowmeter transducer on the measurement accuracy.

Sino-Inst produces and supplies ultrasonic flow meters mainly for measuring water, seawater, industrial sewage, acid and alkaline liquids, alcohol, beer, various oils, and other single homogeneous liquids that can conduct ultrasonic waves. Of course, there are also ultrasonic flowmeters that can measure gas.

According to the measurement method can be divided into Doppler ultrasonic flowmeter, time difference ultrasonic flowmeter, hybrid ultrasonic flowmeter.

A）Doppler type ultrasonic flowmeter

B) time difference ultrasonic flowmeter

C）Mixed ultrasonic flowmeter

Related products:

Find more Ultrasonic Flow Meters for Liquids|Clamp-on|Insertion|inline

Sino-Inst, Manufacturer for Ultrasonic flow detectors. It can measure a single sound-conducting liquid medium of DN 15—150mm. It can measure even liquids such as water, seawater, oil, and slurry.

Sino-Inst’s Ultrasonic flow detectors, 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.

Irrigation Flow Meters for Agriculture Water System

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What is an irrigation flow meter?

The irrigation flow meter is a flow meter designed for agricultural irrigation water counting. Agriculture, horticulture, etc. require water for irrigation. And water is becoming more and more expensive. The installation of flow measurement devices allows for effective monitoring and management of agriculture water systems.
The old mechanical water meters and today’s ultrasonic flow meters and electromagnetic flowmeters are widely used.

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Agricultural irrigation water system

It consists of irrigation canal head project, water transmission and distribution project and field irrigation project.

①Irrigation canal head project has reservoirs, pumping stations, dammed diversion projects, damless diversion projects, wells and other forms. Used to draw irrigation water at the right time and in the right amount.

② water transmission, water distribution projects include channels and canal buildings. Its task is to safely transport and reasonably distribute the water introduced at the head of the canal to all parts of the irrigation area. According to its function and scale, the general fixed channel is divided into dry, branch, bucket, agricultural four levels. Depending on the size of the irrigation area and the terrain, the number of levels of channels can be increased or decreased appropriately. Drainage buildings include diversion buildings, water measuring buildings, restraint buildings, articulation buildings, cross buildings, flood drainage buildings, drainage buildings, etc.

③ Field irrigation project refers to the temporary furrows, water transmission monopoly ditches and field irrigation ditches below the agricultural canals, border fields, and temporary water distribution and water measurement buildings. Used to irrigate the farmland. To meet the needs of normal crop growth or soil improvement.

Extended reading: Industrial VS Residential inline water flow meters

Irrigation flow meters for sale

Magnetic Water Flow Meter
Remote Magnetic Sewage Flow Meter
Insertion Magnetic Flow Meter
Handheld Ultrasonic Flow Meter
Ultrasonic Clamp on Flow Meter
Dual Channel Ultrasonic Water Meter

A 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, a Magnetic Flow Meter is the best flow meter choice.

Read more about Everything You Need To Know About Electronic Flow Meters

The ultrasonic flow meter measures the liquid flow rate quickly and effectively. There are two types of ultrasonic flowmeter technology: Doppler frequency shift and transit time.

Transit time ultrasonic flow meter is most suitable for measuring the flow of cleaning liquid. Therefore, it is the most popular type of ultrasonic meter.

Doppler ultrasonic flow meter can measure the frequency difference of sound waves reflected from bubbles or particles in the airflow. It is suitable for aerated or dirty liquids.

Insertion Ultrasonic Water Flow Meter-Old Style
Insertion Ultrasonic Water Flow Meter-New Style

Card-type water meter with fixed control function, according to the local climate conditions, crops or green plants growth habits, program control can set up to five timed water supply time per day, in order to achieve water-saving irrigation, scientific irrigation.

The open channel flowmeter uses an ultrasonic sensor with a Parshall groove to measure open channel flow. Ultrasonic open channel flow meter is composed of 3 parts: level sensor, water measuring sink, and flow totalizer.

Ultrasonic open channel flowmeters are used to measure the flow of fluids in non-full tubular open channels and natural flowing water surfaces. It is called open channel flow detection. The measuring flume that is not full is called an open channel. The open channel flowmeter measures the water level in the measuring weir trough and then calculates the flow rate according to the water level flow relationship of the corresponding measuring weir trough.

Extended Reading: Chilled Water Flow Meter

Radar flow meter is a fully automatic flow meter based on microwave technology. It adopts advanced K-band plane radar technology. Through non-contact way to measure the flow rate and water level of the water body. According to the built-in software algorithm, it calculates and outputs the real-time section flow and accumulated flow.

The radar flow meter can be used for non-contact flow measurement in rivers, irrigation channels, underground drainage networks, flood control, and early warning. The product features low power consumption, compact size, high reliability, and easy maintenance. The measurement process is not affected by temperature, sediment, river pollutants, floating objects on the water surface, and other factors.

Extended Reading: Collection of Industrial Insertion Flowmeter Type

Extended reading: 2 inch Water Flow Meter

river flow measurement instruments

The methods of river flow measurement are as follows:

1.Flowmeter method
The flow of the river is measured directly using a flow meter.
There are many types of flowmeters, mainly including differential pressure, electromagnetic, trough and weir flowmeters.
It can be selected and used according to the flow range of the actual flow and the test accuracy requirements.

2.Volume method
Pour river water into a container of known capacity and measure the time it takes to fill the container. Repeat the measurement several times. A method of calculating the amount of water by finding its average value t(s).
The method is simple and easy to implement and has high measurement accuracy. Suitable for rivers with small river flow.
However, there should be an appropriate drop between the overflow port and the receiving water body, or an aqueduct can be used to form an error.

3.Buoy method
Select a straight river reach, and measure the cross-sectional area of ​​the water flow within a 2m interval of the river reach. Find the area of ​​its average cross-section.
Drop buoys in the upper reaches of the river and measure the time it takes for the buoys to flow through the identified reaches (L).
Repeat the measurement several times to obtain the average value (t) of the required time.
The flow rate (L/t) can be calculated.
The flow can then be calculated as follows:

Q=60V*S

where Q is the water flow, and the unit is m^3/min.
v is the average velocity of water flow, and its value is generally 0.7L/t, m/s.
S is the average cross-sectional area of ​​water flow, in m^2.

4.Flow meter method
By measuring the cross-sectional area of ​​the water flow, the river flow rate is measured with a current meter to calculate the river flow.
When measuring, the number of vertical measuring points and the number of horizontal measuring points need to be determined according to the depth and width of the channel.
This method is simple, but it is easily affected by water quality, and it is difficult to achieve continuous determination.

5.Acoustic Doppler flow velocity measurement
Acoustic Doppler flow velocity measurement is developed using the principle of acoustic Doppler. It can simultaneously measure the cross-sectional shape, water depth, flow velocity and flow rate of the river bed at one time, and is suitable for flow monitoring of large rivers.

The flowmeter’s host and transducer are housed in a waterproof container. All immersed in water when working. It is connected with a portable computer through a waterproof cable, and the operation and control of the flowmeter are carried out on the portable computer.
From the initial blind zone of more than 1m, it has been reduced to the so-called “zero blind zone”. The section unit is reduced to the current 0.05~0.25m. Make it possible to apply it on wide and shallow rivers.

Read more about: Common River Water Level Measurement Methods

Battery operated electromagnetic flow meter-GRPS-new irrigation water flow meter

GPRS wireless remote electromagnetic flowmeter inherits the advantages and functions of the original electromagnetic flowmeter and supports GPRS wireless communication.

Only a mobile phone card with GPRS wireless Internet access function is required, and you can easily log in to the Internet and establish a connection with a remote computer without connecting other module devices. Support Kingview.

The battery-powered converter comes standard with a regular lithium battery pack that lasts 3–6 years. If equipped with a high-capacity lithium battery pack, the continuous working time will be longer.

It can easily realize remote monitoring of the electromagnetic flowmeter’s instantaneous flow, instantaneous flow rate, flow percentage, fluid conductance ratio, forward cumulative value, reverse cumulative value, alarm status and other data. With disconnection automatic connection function, support dynamic IP address.

This Battery operated electromagnetic flow meter has become the choice of many users.

How to Select the Right Agriculture Flow Meter

Due to the modernization of agriculture and the realization of precision agriculture, flowmeters are bound to play an increasingly important role in farmland irrigation.
Therefore, on the basis of a comprehensive comparison of the measurement methods and characteristics of various flowmeters on the market. You should choose flow meter products that are more in line with the requirements of farmland water conservancy irrigation, safe, reliable, economical and durable.

The principle of choosing a flowmeter is to have a deep understanding of the structural principles and fluid characteristics of various flowmeters. At the same time, the selection should be made according to the specific situation of the site and the surrounding environmental conditions. Economic factors must also be taken into account.

In general, you should choose from the following five aspects:

① Performance requirements of the flowmeter;

  • Whether to measure flow (instantaneous flow) or total amount (cumulative flow);
  • Accuracy requirements;
  • Repeatability;
  • Linearity;
  • Flow range and range;
  • Pressure loss;
  • Output signal characteristics and flowmeter response time, etc.

② fluid characteristics;

  • Fluid temperature and pressure
  • fluid density
  • Viscosity
  • Chemical corrosion and scaling
  • compression factor

③ Installation requirements;

  • Field piping wiring
  • The flow direction of the fluid
  • The upstream and downstream straight pipe sections of the flowmeter
  • Pipe diameter and pipe vibration
  • The installation position of the valve
  • Protective accessories
  • Electrical connection and electromagnetic interference
  • Pulsating flow and unsteady flow

④ Environmental conditions;

  • Ambient temperature
  • Ambient humidity
  • Security
  • Electrical interference

⑤ The price of the flow meter.

  • Installation fee
  • Running cost
  • Testing fee
  • Maintenance costs and spare parts costs, etc.

Frequently
Asked
Questions

Help Center

In theory, there are many ways to measure irrigation flow.
However, from a practical application point of view I will tell you:

If it is a closed pipe, use a flowmeter. Electromagnetic flowmeters or ultrasonic flowmeters are both good choices.
If it is an open channel, then an open channel flow meter is used.

If you want to divide the flow meter into three categories. I think it can be divided into volumetric flowmeters, mass flowmeters, and velocity flowmeters.

If you choose a water meter. Then the diameter of the water meter is determined according to the rated flow of the water meter and the user’s water consumption and water use method.

If you choose a flow meter. It is necessary to combine the selection reference parameters mentioned above.

The general measurement is to use an electromagnetic flowmeter.

Magnetic flowmeters use the principle of Faraday’s Law of Electromagnetic Induction to measure the flow rate of liquid in a pipe. In the magnetic flowmeter pipe parts, a magnetic field is generated and channeled into the liquid flowing through the pipe.

As fluid flows through the magnetic field, conductive particles in the fluid create changes. This variation is used to measure and calculate the velocity of water flow through the pipe. When the fluid moves faster, more voltage is generated. The electronic transmitter processes the voltage signal to determine the liquid flow.

Read more about Digital Water Flow Meters

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Sino-Inst is Manufacturer of Irrigation Flow Meters. We supply more than 20 kinds of Irrigation Flow Meters. 60% magnetic flow meter, 20% ultrasonic flowmeters, and other types of flowmeters.

Irrigation Flow Meters are mainly used for flow measurement of Agriculture Water System.
It can measure even liquids such as water, seawater, oil, and slurry.

Irrigation Flow Meters enable stable water measurement and control. This greatly meets the measurement needs of many Farm and irrigation industry applications. Can be used from small to large tubes.

Sino-Inst’s Irrigation 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 Irrigation Flow Meters, level sensor, or other device, give us a call.

Static Pressure vs Dynamic Pressure vs Total Pressure

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You may have heard of Static Pressure, Dynamic Pressure and Total Pressure. Especially in some industrial process pipe parameters. So what are Static Pressure, Dynamic Pressure and Total Pressure? What is the difference between them? How are they measured? Let’s take a look together.

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Static pressure vs dynamic pressure vs total pressure

According to the knowledge of fluid mechanics. The vertical force acting on the unit area of the fluid is called pressure. When the air flows along the inner wall of the duct, its pressure can be divided into static pressure, dynamic pressure and full pressure. The unit is mmHg or kg/㎡ or Pa, respectively.

Static pressure (Pi).

What is static pressure?

Static pressure is the pressure generated by the air molecules hitting the duct wall due to irregular movement.
When calculating, the static pressure with absolute vacuum as the calculation zero points are called absolute static pressure.
The static pressure with atmospheric pressure as the zero point is called relative static pressure.
The static pressure of air in air conditioning refers to the relative static pressure.
The static pressure is positive when it is higher than atmospheric pressure, and negative when it is lower than atmospheric pressure.

Dynamic pressure (Pb).

What is dynamic pressure?

Dynamic pressure refers to the pressure generated by the flow of air, as long as the air flow in the duct has a certain dynamic pressure, and is positive. Dynamic pressure = 0.5 * air density * wind speed 2 .

Total pressure (Pq).

What is total pressure?

The total pressure is the algebraic sum of the static and dynamic pressures: Pq=Pi+Pb .

The total pressure represents the total energy of 1m3 of gas. If the atmospheric pressure is the starting point of the calculation, it can be positive or negative.

Extended reading: Pressure indicator transmitters

Extended reading: Pressure Sensor Applications-Featured Industry Applications

The difference between static pressure, dynamic pressure and total pressure

Different nature

  1. Total pressure: The pressure measured parallel to the wind flow, directly opposite to the direction of the wind flow.
  2. Static pressure: the pressure on the surface of an object at rest or in uniform linear motion.
  3. Dynamic pressure: When the object is moving in the fluid, the surface in the direction of the fluid movement. The fluid is completely blocked, where the fluid velocity is 0. Its kinetic energy is transformed into pressure energy, and the pressure increases.

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Features are different

1.Total pressure: air conditioning units or fresh air units are often installed at the end of the fan, the fan outlet wind speed is high, high dynamic pressure, static pressure is small. Engineering often installed at the exit of the anechoic static pressure box, reduce the dynamic pressure, increase the static pressure. At the same time, the same flow, muffling effect.

2.Static pressure: with no noise, no vibration, no impact.

3.Dynamic pressure: only the directional flow of air to show dynamic pressure. Dynamic pressure is directional, only the plane perpendicular or oblique to the direction of wind flow pressure. The plane of the vertical flow direction to bear the maximum dynamic pressure, the plane of the parallel flow direction to bear the dynamic pressure is zero. In the same flow section, because the wind speed at each point is not equal, the dynamic pressure varies. Dynamic pressure is not absolute pressure and relative pressure, always greater than zero.

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Different applications

  • Total pressure: applied to air conditioning or fan products.
  • Static pressure: applied to fluid dynamics.
  • Dynamic pressure: applied to mines, aerospace, etc.

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What is an example of static and dynamic pressure?

Example of static pressure: When water is stored in a closed container, the pressure generated by the water in the container is static pressure. For example, water stored in a water tower develops pressure due to its height.

Example of dynamic pressure: When water flows in a pipe, in addition to the static pressure due to the weight of the water, there is also pressure due to the flow speed of the water. This part of the pressure is dynamic pressure. For example, the pressure created when water from a faucet hits the bottom of a wash basin.

Dynamic Pressure Calculator

Dynamic pressure is the kinetic energy of a flowing fluid – liquid or gas – per unit volume – and can be expressed as

pd = 1/2 ρ v²

Where:
pd = dynamic pressure (N/m2 (Pa), lbf/ft2 (psf))
ρ = density of fluid (kg/m3, slugs/ft3)
v = velocity (m/s, ft/s)

Online Dynamic Pressure Calculator

What is a dynamic pressure sensor?

The piezoelectric effect is the main operating principle of dynamic pressure sensors. Dynamic pressure sensors cannot be used for static measurements.

This is because the charge after an external force is only saved when the circuit has an infinite input impedance.

This is not the case in practice, so this determines that dynamic pressure sensors can only measure dynamic stresses.

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Static pressure sensor and dynamic pressure sensor difference

  1. Diaphragm pressure sensor is according to the structure of the sensor, according to the sensing principle diaphragm pressure sensor can be divided into different types such as piezoresistive, strain gauge, inductive, capacitive, piezoelectric, etc.
  2. Among the above different principles of pressure sensors, piezoelectric pressure sensors are only suitable for measuring dynamic pressure. Therefore, dynamic calibration is required; other dynamic and static pressures can be measured. The most applications belong to the quasi-static measurement of very low frequency. Therefore, static calibration is the most used form of calibration. When the measured pressure band is wide, all kinds of pressure sensors should do frequency response calibration.

Extended reading: Silicon Pressure Sensor

Applications of dynamic pressure sensors

Dynamic pressure sensors are mainly used in the measurement of acceleration, pressure and force.

Dynamic pressure sensors are also widely used in biomedical measurements. For example, ventricular catheter microphones are made of piezoelectric sensors. Because dynamic pressure measurements are so common. This is why dynamic pressure sensors are so widely used.

Dynamic pressure transducers are used in a wide range of applications, typically to measure speed, pressure, and force. Therefore, they have a very high value in some products.

Extended reading: Best Price Ceramic Pressure Sensor

Frequently
Asked
Questions

Help Center

The static pressure sensor is based on atmospheric pressure or absolute vacuum, and compares the difference between the measured pressure and atmospheric pressure or absolute vacuum.

A static pressure sensor can be thought of as a specific form of differential pressure sensor. However, due to the measurement requirements, there will be large differences in the structure of the two.

In ventilation systems, static pressure is the pressure exerted by the air inside a building relative to the outside air pressure when the exhaust fan is turned on. Measuring and maintaining proper negative pressure allows ventilation systems to mix outside and inside air more efficiently.

Extended reading: Industrial Pressure Transmitters|Buy from the manufacturer

Dynamic pressure, when an object moves in a fluid, on the surface facing the direction of fluid motion, the fluid is completely blocked. The fluid velocity here is 0. Its kinetic energy is converted into pressure energy. The pressure increases. Its pressure is called total resistance pressure . Abbreviated as total pressure or total pressure, represented by P. The difference between it and the pressure at the undisturbed place (ie static pressure, represented by P static) is called dynamic pressure (represented by P dynamic)

Extended reading: Featured Diaphragm Seal Pressure Transmitters

The duct static pressure sensor is a detection instrument that mainly detects the difference of wind pressure on both sides of the filter. Real-time data monitoring and measurement of gas positive pressure, negative pressure and differential pressure can be realized through the wind pressure sensor. Equipped with a pitot tube pressure device, it can realize the three-in-one detection of wind pressure, wind speed and air volume.

Extended reading: how to calibrate a pressure transmitter

Diaphragm pressure sensors are based on the structure of the sensor. According to the sensing principle, diaphragm pressure sensors can be divided into different types such as piezoresistive, strain gauge, inductive, capacitive, and piezoelectric.

Among the above-mentioned pressure sensors with different principles, piezoelectric pressure sensors are only suitable for measuring dynamic pressure. Therefore, dynamic calibration is required;

Other dynamic and static pressures can be measured, and the most widely used is the quasi-static measurement with a very low frequency. Therefore, static calibration is the most widely used calibration form. When the measured pressure frequency band is wide, all kinds of pressure sensors should be calibrated for frequency response.

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Sino-Inst offers over 20 Pressure Transducers.

About 50% of these are 4-20ma Low-Pressure Transducers, 40% are Differential Pressure Gauge, and 20% are Diaphragm Seal Pressure transmitters, 20% are 4-20ma differential pressure transmitters.

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

Sino-Instrument is a globally recognized supplier and manufacturer of Pressure Transducers, located in China.

The top supplying country is China (Mainland), which supply 100% of Pressure Transducers respectively.

Sino-Inst sells through a mature distribution network that reaches all 50 states and 30 countries worldwide.

Pressure Transducers products are most popular in Domestic Market, Southeast Asia, and Mid East. 

You can ensure product safety by selecting from certified suppliers, with ISO9001, ISO14001 certification.

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The influence of Reynolds number on the accuracy of the flow meter

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What is Reynolds number?

Reynolds number is a dimensionless number that can be used to characterize the flow of a fluid. The ratio of the inertial force Fg and viscous force (internal friction) Fm during fluid flow is called Reynolds number. It is expressed by the symbol Re. Re is a factorless quantity. The Reynolds number can be used to distinguish the flow of fluid is laminar or turbulent. It can also be used to determine the resistance to the flow of an object in a fluid.

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Instrument constant of flow meters, i.e. Reynolds number

Reynolds number is an infinite parameter used as a criterion to determine the flow pattern of a fluid as it flows through a pipe. It is related to pipe diameter, flow rate, and medium viscosity.

The first used to determine the flow pattern of the fluid is turbulent flow through laminar flow. A side Re greater than 3200 or more can be judged as turbulent flow. Of course, from the laminar flow to the turbulent flow of the Reynolds number has a transition. So be specific and say that the Reynolds number must be greater than a certain value to say is to restore turbulent flow. Less than a certain value is said to be restored laminar flow.

Re = ρvd/μ, where v, ρ, μ are the fluid velocity, density and viscosity coefficient, d is a characteristic length. For example, if fluid flows through a circular pipe, d is the equivalent diameter of the pipe.

When measuring the flow rate of a fluid in a pipe, it is often necessary to understand its flow state, velocity distribution, etc. Reynolds number is to characterize the fluid flow characteristics of an important parameter.

Fluid flow inertia force Fg and viscous force (internal friction) Fm ratio called Reynolds number. Re is a factor less quantity.

The Reynolds number is small, which means that the fluid flow between the viscous force between the masses dominates, the fluid masses parallel to the inner wall of the pipe flow regularly, laminar flow state.

Reynolds number is large, which means that the inertia force dominates, the fluid is the turbulent flow state, general pipe Reynolds number Re < 2000 for laminar flow state, Re> 4000 for turbulent flow state, Re = 2000 ~ 4000 for the transition state.

In different flow states, the law of motion of the fluid. The distribution of velocity is different, so the average velocity of the fluid in the pipeline υ and the maximum velocity υmax ratio is also different. Therefore, the size of the Reynolds number determines the flow characteristics of viscous fluids.

When the external conditions are geometrically similar (geometrically similar pipes, fluid flowing through geometrically similar objects, etc.), if their Reynolds numbers are equal, the fluid flow state is also geometrically similar (hydrodynamically similar). This law of similarity is the basis for the standardization of flow measurement throttling devices.

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The influence of Reynolds number on the vortex flowmeter

The influence of Reynolds number on the vortex flowmeter in a certain range of Reynolds number. Vortex flowmeter output frequency signal with the volume of flow through the measuring tube between the relationship is not affected by the fluid properties (density, viscosity) and components. That is, the flow coefficient is only related to the vortex generator and the shape and size of the pipe.

Therefore, only in a typical medium in the calibration of its flow coefficient and applicable to a variety of media. This is a major advantage of the vortex flowmeter.

However, if the Reynolds number exceeds this range, it will have an impact.

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Vortex flowmeter working principle

In the fluid flow in the pipeline set a vortex generator (resistance fluid). So in the volume downstream of the generator will alternately produce a regular vortex. This vortex is called Kaman vortex street.

The vortex generator is the main component of the detector. It is closely related to the flow characteristics (meter coefficient, linearity, range, etc.) and resistance characteristics (pressure loss) of the meter, and the requirements for it are as follows.

A vortex flowmeter can control the vortex in the direction of the axis of the vortex generator synchronous separation.
In a wide range of Reynolds numbers, there is a stable vortex separation point, maintaining a constant Strohal number.
The ability to produce a strong vortex street with a high signal-to-noise ratio of the signal.
Simple shape and structure, easy processing and standardization of geometric parameters, as well as installation and combination of various detection elements.
materials should meet the requirements of fluid properties, corrosion resistance, abrasion resistance, and resistance to temperature changes.
The inherent frequency is outside the frequency band of the vortex street signal.

Due to strict environmental requirements, some process industries, especially chemical, paper, and water treatment, are all placed under the strict monitoring of the agency. This will drive the vortex flowmeter production increase.

In addition, the privatization of municipal water treatment has become the trend, which will generate new investment to update the aging water treatment and sewer systems.

Multi-variable vortex flowmeters, which can measure temperature and pressure in addition to flow, are also in commercial use. Although its output is negligible, growth can be expected throughout the forecast period.

This enhanced measurement capability allows users to purchase fewer meters, requiring fewer process measurement points and thus fewer potential leak paths.

Read more about: How Vortex Flow Meter measure efficiently? For steam, gas, liquid 

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