A differential pressure sensor is used to measure the difference between two pressures. It uses a differential pressure measuring element. Element isolated by a stainless steel corrugated diaphragm. This article will introduce the differential pressure sensor in detail. You will have a comprehensive understanding of differential pressure sensors.
What is Differential Pressure?
Differential pressure is a core parameter in industrial measurement. Differential pressure (Δp) is calculated by the relative difference between two pressure points:
(Δp=P₁-P₂).
We often use differential pressure gauges to measure the positive pressure end and the negative pressure end. In industrial fields such as petroleum, chemical industry, and metallurgy.
The Function of a Differential Pressure Sensor
Differential pressure sensors can be used to measure differential pressure/liquid level/density/ and flow.
Differential pressure sensors:
It measures differential pressure by detecting changes in capacitance. Its core structure consists of a stainless steel base, a corrugated isolation diaphragm, a glass layer, and a measuring diaphragm.
The metal film at the edge of the glass layer forms a capacitive structure with the central elastic diaphragm. The silicone oil medium transmits the pressure to the measuring diaphragm. The deformation of the diaphragm under the action of differential pressure causes a capacitance difference.
The sensor consists of a symmetrical structure with two chambers filled with silicone oil, which can transmit the differential pressure to the measuring diaphragm. It has high accuracy and reliability in the field of industrial measurement.
Differential pressure flow meter:
Differential pressure sensors use the Bernoulli principle to measure flow. It calculates the flow rate of the fluid by measuring the flow pressure difference in the pipeline. Thereby inferring the flow rate. Common devices include orifice plates, nozzles, venturi tubes, etc.
Differential level transmeter:
The principle of the differential pressure sensor measuring liquid level:
The pressure at different heights inside the liquid is different. And the pressure per unit area = liquid level height × liquid specific gravity. By measuring the pressure at a certain height inside the liquid. The height from this point to the liquid surface can be obtained.
Since the upper part of the container (liquid surface) itself may also have pressure. The upper pressure will affect the measurement results. Therefore, a differential pressure transmitter is needed to simultaneously measure the pressure. The pressure is above and below the liquid surface and offset (measure the differential pressure). To obtain the liquid surface height.
Differential Pressure Density Meter
Differential pressure sensors can also be used to measure density. Differential pressure measurement principle: The differential pressure density meter uses the gravity difference △P=ρgh generated by the liquid column. When h is constant, the differential pressure value measured by the differential pressure transmitter is divided by the gravity acceleration and length to obtain the density value.
Sino-Inst can supply various measuring instruments. Our products can measure level, temperature, flow and pressure. If you have any needs, please contact us.
How does a Differential Pressure Sensor Work?
A differential pressure sensor can measure the pressure difference between two locations. Its working principle is based on the deformation of an object. When it is subjected to different pressures.
Specifically, a differential pressure sensor usually consists of two interconnected chambers. Each chamber is connected to a pressure pipe. When fluids or gases pass through the sensor, they enter the two chambers and apply pressure. These pressures are transmitted to the measuring unit of the sensor through the interconnected pipes.
The measuring unit is generally made of sensitive materials. Such as semiconductors or metal sheets. When subjected to pressure, these materials will produce a small displacement. The displacement is proportional to the pressure.
These displacements are converted into electrical signals using external electronic circuits and amplified. And finally, a signal corresponding to the pressure difference is output. This process achieves accurate measurement of the pressure difference of the fluid or gas.
What does a Differential Pressure Sensor do?
Differential pressure sensors can be used to measure liquid level and flow. Differential pressure sensors can be used in the following industries:
Chemical Industry
Differential pressure sensors are widely used to monitor and control pipeline pressure differences. By measuring the pressure difference between two pipelines, the flow state of the fluid can be understood in real time. This enables accurate control of chemical equipment.
Differential pressure sensors are also used to monitor the blockage of filters, pressure changes in reactors, etc.
It provides important safety guarantees for chemical production.
Automotive Industry
Differential pressure sensors are used to measure the exhaust pressure difference between the front and rear channels of the engine exhaust particulate filter (DPF).
Medical Equipment Field
Differential pressure sensors are used to monitor air pressure changes in ventilators, pressure control of hemodialysis machines, etc.
Meteorological Monitoring
Differential pressure sensors are used to measure the atmospheric pressure difference at different altitudes. thereby calculating meteorological parameters such as wind speed and direction. This is of great significance to fields such as weather forecasting and aviation safety.
How to Check a Differential Pressure Sensor?
If the differential pressure sensor fails, it may affect the normal operation of the entire system. At this time, it is very important to troubleshoot the fault of the differential pressure sensor.
Physical Inspection
1. Appearance Inspection:
Check whether the appearance of the sensor is damaged, deformed or corroded. These problems may cause the sensor performance to deteriorate or fail completely.
2. Cable Inspection:
Check whether the sensor’s connection cable is intact, without damage, breakage or poor contact. Cable damage may cause data transmission interruption or error.
3. Environmental Condition Inspection:
Confirm whether the environment in which the sensor is located meets its working requirements. such as temperature, humidity, etc.
Unsuitable environmental conditions may affect the performance and life of the sensor.
Use a multimeter to detect
If no obvious problems are found in the physical inspection. A multimeter can be used to further detect the electrical performance of the sensor.
1. Set up the multimeter:
Set the multimeter to the appropriate voltage or resistance measurement position. Determine the appropriate measurement range according to the sensor’s operating manual.
2. Measure voltage or resistance:
Connect the probe of the multimeter to the corresponding port of the sensor. Measure its output voltage or resistance value.
If the measured value is significantly different from the standard value in the specification. It may indicate that the sensor is damaged.
3. Compare the measurement results:
Compare the measurement results with the technical indicators of the sensor. If the measured value is beyond the normal range, it can be preliminarily determined to be a sensor failure.
Diagnostic software detection
For some differential pressure sensors. You can also check their status through diagnostic software.
1. Connect the sensor to the diagnostic software:
Connect the sensor to the computer through the appropriate interface. Start the diagnostic software.
2. Read sensor data:
Read the real-time data of the sensor through the software. including parameters such as pressure difference and temperature.
3. Analyze data: Analyze the working status of the sensor based on the read data. If the data is abnormal or fluctuates too much, it may mean that there is a problem with the sensor.
How to Calibrate a Differential Pressure Sensor?
Due to the interference of various factors, the zero point of the differential pressure sensor may sometimes be offset. Therefore, it is very necessary to calibrate the zero point of the differential pressure sensor regularly.
Methods for zero point calibration of a differential pressure sensor
1. Using atmospheric pressure
The zero point of the differential pressure sensor can be calibrated by using atmospheric pressure. The specific operation method is as follows:
(1) Connect the differential pressure sensor to the measurement system without any pressure.
(2) Expose the two ports of the differential pressure sensor to the atmosphere at the same time. Wait for a while until the output of the differential pressure sensor stabilizes.
(3) Record the output value of the differential pressure sensor at this time, which is the zero point value.
2. Manual zero adjustment
Manual zero adjustment means to calibrate by manually adjusting the zero point value of the differential pressure sensor. The specific operation method is as follows:
(1) Connect the differential pressure sensor to the measurement system and preheat it.
(2) Record the output value of the differential pressure sensor without any pressure. This value is the current zero point value.
(3) According to actual needs, manually adjust the zero value of the differential pressure sensor until the output value is zero.
(4) Connect the differential pressure sensor to the measurement system. Perform actual measurement.
3. Automatic zeroing
Automatic zeroing refers to calibration by using the automatic zeroing function of the instrument. The specific operation method is as follows:
(1) Connect the differential pressure sensor to the instrument and preheat it.
(2) Start the automatic zeroing function of the instrument without any pressure.
(3) Wait for a while until the instrument completes automatic zeroing.
(4) Connect the differential pressure sensor to the measurement system. Perform actual measurement.
Sino-Inst is a supplier from China. We have many years of experience in instrument measurement.
Sino-Inst supplies various types of sensors. Our differential pressure sensors come with a one-year warranty. We offer international express delivery. We support a variety of custom solutions. Our measuring instruments are used in a variety of industries. We have many successful cases. If you have measurement problems, please contact us now!
Why do We Measure Differential Pressure?
Differential pressure measurement is the pressure measurement relative to the ambient atmospheric pressure. It is used to quantify the measured pressure.
In liquid level measurement, the differential pressure principle can solve the error of liquid height.
In flow meters, square root operation and temperature and pressure compensation are used to improve measurement accuracy.
How do You Know If Your Differential Pressure Sensor is Bad?
1. Abnormal output signal
An abnormal output signal of a differential pressure transmitter is one of the common faults. Possible problems include output signal fluctuation, large deviation or no output at all.
Reason: unstable input signal, sensor damage or circuit failure.
2. Failure of temperature compensation
Temperature compensation of the differential pressure transmitter is an important factor to ensure measurement accuracy. If temperature compensation fails, the measurement result will be inaccurate.
Reason: damaged temperature sensor or inaccurate calibration.
3. Zero drift
The output signal deviates from zero when there is no pressure input.
Reason: mechanical zero offset, transmitter aging or circuit failure.
4. Leakage
The leakage of a differential pressure transmitter will lead to inaccurate measurement results.
Reason: aging of seals, loose sealing or improper installation.
