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.

What is a pressure sensor?

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.

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

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

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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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.

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