What Is a Fluid Pressure Sensor?

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

Fluid Pressure Sensor

What is a pressure sensor?

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

How do fluid pressure sensors work?

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

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

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

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

Extended reading : Types of pressure sensors

Applications of fluid pressure sensors

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

In the hydraulic system, the pressure sensor is mainly used to complete the closed-loop control of the force.

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

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

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

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

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

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

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

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

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

Fluid pressure sensors play an important role in injection molds.

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

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

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

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

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

Pressure Sensor For Liquid Level Measurement

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

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

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

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

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

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

Extended reading: Differential pressure level transmitter working principle

Pressure Sensors For Flow Measurement

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

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

Extended reading: flow rate and pressure relationship

Differential pressure flow meter advantages and disadvantages

Upstream and Downstream Flow Straight Pipe Requirements-for Flowmeter Installation

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

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

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

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

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

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

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

Extended reading: Pressure transmitter working principle

Pressure transmitters can be categorized into four main types:

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

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

Extended reading: Digital Flow Meters

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

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

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

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

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