A guide to differential pressure measurement including explanations, applications and choice of products for measuring pressure with an differential pressure.
Differential pressure is the difference in pressure between two separate points.
A differential pressure can be measured between two points on independent systems or between two different points on the same system.
Differential Pressure Transmitters - Differential pressure transmitters for measuring the DP of fluids and gases across particle filters and along a length of pipe to monitor flow.
Low Differential Pressure Transmitters - Low differential pressure transmitters for measuring small pressure differences between two measurement points on across ventilation fans, air filters or clean room walls.
Low Range DP Voltage Output Transducers - Low range differential pressure transducers are essential for monitoring and controlling air movement in a variety of applications, including ventilation systems, air extraction systems, and building management systems.
High Accuracy DP Sensors - High accuracy differential pressure sensors for measuring with a high degree of accuracy and resolution to obtain precise dp readings.
Digital Interface DP Sensors - Explore our range of differential pressure sensors featuring RS485, RS232, and USB digital interfaces.
Air DP Sensors - Air differential pressure sensors play a vital role in maintaining environmental control and safety within critical applications such as cleanrooms, laminar flow cabinets, and ventilation systems.
Intrinsically Safe DP Sensors - Intrinsically safe differential pressure sensors are essential for accurate pressure measurement in hazardous environments where explosive atmospheres may be present.
Rangeable DP Sensors - Rangeable differential pressure (DP) sensors provide a high degree of flexibility in measurement applications by allowing users to adjust the output signal.
Low Range DP Sensors - Low range differential pressure sensors for measuring very small pressure differences.
Wet / Wet Differential Pressure Sensors - Wet/Wet differential pressure transducers and transmitters which are compatible with liquids on both positive and negative side process connections.
Differential Pressure Voltage Output Transducers - Differential pressure transducers with amplified volts output for measuring the dp of liquids and gases.
Applications
The main use for a differential pressure sensor is to measure the difference in fluid or gas pressure across a restriction in a pipe. The flow can then be determined by converting the differential pressure reading with bernoulli’s equation. Since flow is proportional to the square root of the differential pressure in a closed pipe it is sometimes preferred to use a square root output signal from the differential pressure sensor to simplify the conversion to a flow measurement.
Other applications for measuring differential pressure are as follows:
Hydrostatic level measurement of a tank’s content, where the gas at the top of the tank is not vented. The difference in pressure between the bottom and the top is measured to determine the true hydrostatic pressure.
Leakage monitoring by measuring the difference in pressure between a controlled reference pressure and the component under test pressurised to the same pressure.
Airspeed using a Pitot tube which provides two air channels, one for measuring the total air pressure facing the airflow and the other for the static pressure measured perpendicular to the air-flow. The difference between the two channels provides the air velocity pressure. This method is used on aircraft to measure air speed and in wind tunnels to simulate air velocity for testing the aerodynamics of an object.
Questions & Answers
Differential vs Gauge
When do you need to measure differential pressure instead of gauge pressure?
You would you use a differential when you need to measure pressure between 2 connection points, and when the reference pressure (negative side) is not the same as atmospheric pressure.
Which side of DP transmitter to connect to vacuum
Which side of the impulse line connections for a dp transmitter is the blower vacuum or suction side?
If the output of the dp transmitter is scaled for a positive pressure range, e.g. 0 to +1 bar = 4 to 20 mA, then you can measure 0 to -1 bar suction but connecting the vacuum to the negative side, and leaving the positive side vented to atmosphere.
Related Help Guides
- Measuring liquid level in a sealed tank with a hydrostatic pressure sensor
- Measuring the difference in air pressure between rooms
- Measuring negative pressure using a positive differential pressure range
- Measuring liquid level in a tank using a dp sensor
- Measuring density of a liquid using a dp sensor
- How do you measure flow rate with a dp cell
- Measuring vacuum as a negative gauge pressure using a dp sensor
- What can a DP sensor be used to measure beyond differential pressure?
- Measuring flow rate of a liquid or gas using a dp sensor
- Measuring gauge pressure using a dp sensor
- Measuring absolute pressure using a dp sensor
- Measuring barometric pressure using a dp sensor
- Measuring vacuum as an absolute range using a dp sensor
- What does the suffix a, abs, d, dp and diff, g, rel and sg mean after the pressure units in a pressure range?
Related Technical Terms
Related Online Tools
Related Product and Application Guides
Glossary of Pressure Reference technical terms
- Absolute Pressure
- Compound Pressure Ranges
- Gauge Reference Pressure
- MSL – Mean Sea Level
- Negative Gauge Pressure
- Reference Pressure
- SG – Sealed Gauge
- Suction Pressure
- Vacuum
- Vented Cable
- Vented Gauge
Help from Pressure Reference resources
- Pressure device not reading zero? Get troubleshooting tips
- Measuring vacuum with negative gauge or absolute ranges
- What is the difference between gauge and absolute pressure measurement
- What does negative and positive gauge pressure mean
- Measuring negative pressure using a positive differential pressure range
