The pressure range is the most complicated and confusing specification parameters to define for a pressure sensor. If you do not fully understand the different types of pressure that can be measured, you are likely to end up reading pressures inaccurately, or worse still, damaging the sensor before you have had a chance to correct the situation.
The two main questions that you need to ask yourself are, what is the range of pressure I need to measure over, and what baseline pressure will it be relative to?
Reference Pressure
If you are measuring the direct pressure of a gas or liquid process then you will need either a gauge (g, rel) or absolute (abs, a) reference pressure range depending on whether you need to track relative to atmospheric air pressure changes (zero output = atmospheric pressure) or measure independently of atmospheric pressure changes (zero output = perfect vacuum). This will define the baseline pressure required, and will dictate the type of pressure sensor needed, since typically a pressure sensor will be manufactured to only measure gauge or absolute pressure, and cannot be modified once it has been built.
Featured gauge reference pressure sensor products
Ship lubrication oil pump pressure transmitter with DNV/GL marine approval certificate - DNV/GL certified DMK457 pressure transmitter for reliable monitoring of ship lubrication oil pumps. 0 to 6 bar range, and 4-20mA output.
100psig range 4-20mA output helium gas pressure sensor for research use - Gauge pressure sensor with 4-20mA output for measuring helium gas in research applications. Features all-welded stainless steel construction and a 1/4 NPT male process connection.
Featured absolute reference pressure sensor products
DS200 Combined Pressure Switch, Gauge and Sensor - Three in one electronic pressure switch, digital pressure gauge and pressure sensor with pressure ranges from 100 mbar up to 600 bar (1.5 to 9000 psi).
DMP331P Hygienic Flush Pressure Transmitter - Sanitary pressure sensor wth exposed diaphragm with no crevices for high temperatures up to 300 Degrees Celsius in ranges from 100mb up to 40 bar gauge or absolute
If you are measuring pressure between two points such as either side of an extraction fan, or across a filter, then you will need a differential pressure (dp) sensor.
Featured differential pressure sensor products
PrimAtü 10 Low Cost Low Range Differential Air Pressure Transducer - The PrimAtü 10 low cost low range differential air pressure transducer can detect and display both positive and negative differential pressure variations of very low low pressure ranges from 0.5 up to 1000 mbar/hPa, and output the pressure as a 4-20mA, 0-20mA or a 0-10Vdc analog output.
Low-range air pressure monitoring in raised floor plenums using a wireless SNMP gateway - This application required a robust method for maintaining constant pressure in a data center's underfloor plenum. The solution combines a sensitive ±25 Pa differential pressure sensor with a wireless transmitter and an Ethernet gateway that provides SNMP protocol support for seamless integration with existing network monitoring systems.
Pressure Units
Pressure ranges are typically specified by the manufacturer in bar (bar)or pounds force per square inch (psi) for medium to high pressures, and millibars (mbar), hectopascals (hPa), pascals (Pa) or inches of water column (inH2O, inWG, inWC) for low pressures. If your required pressure range is in other units then use a pressure converter to determine the pressure in common units.
Over-Range Pressure
It is important to think about the maximum pressure to be measured and the likely peak pressure that could be generated by the measured process. If there is a large difference between the two pressures then choosing a pressure sensor with a high overpressure rating to match the peak pressure is imperative to prevent calibration disturbance, mechanical damage or failure of the sensor.
Negative Pressure
Occasionally it is necessary to measure negative pressure or pressures below the baseline reference pressure. It is only possible to do this with a gauge reference or differential pressure sensor. For example you may want to measure suction or vacuum pressure which are pressures between full vacuum and atmospheric pressure. Another example of measuring negative pressure would be to apply a reverse the differential pressure across an air filter periodically, as a preventive maintenance measure to clean the air filter and improve air flow.
Compound Ranges
Negative pressure ranges can also be combined with positive pressure ranges to create a compound range or a bidirectional range. These can be used to combine vacuum and positive pressure ranges, or for measuring ventilation pressures in a duct where the air could be flowing in either direction.
Featured negative pressure sensor products
DCT531P RS485 Modbus RTU Flush Pressure Sensor - RS485 Modbus RTU serial interface pressure sensor with exposed all welded stainless steel 316L flush diaphragm in ranges from 100mb up to 40 bar gauge or absolute.
Suction Pressure Transducers - Choose suction pressure transducers with 0-5V or 0-10Vdc outputs. Ideal for measuring suction from millibars to 1 bar, ensuring linear and precise vacuum monitoring.
Liquid Head Pressure
It is also very common to use pressure sensors to measure liquid level by measuring the liquid head pressure. These pressure ranges are often specified in meters or feet of water column. Due to the variance in liquid density it is also possible to have specifically scaled ranges, for example 1.078 bar for a 10 metre high tank which contains a liquid of a slightly different density to water.
Featured liquid head pressure sensor products
OEM sensor for diesel tank level measurement - Submersible hydrostatic level sensor for OEM integration in diesel fuel tanks. Low-power, 0.5 to 4.5V output.
Seawater Hydrostatic Liquid Level Sensors - Submersible hydrostatic level sensors designed for long-term immersion in seawater, engineered with corrosion-resistant materials to withstand harsh coastal and offshore environments.
Related Help Guides
- Not reading zero when pressure is vented to atmosphere
- Measuring vacuum with negative gauge or absolute ranges
- What is the difference between gauge and absolute pressure measurement
- What is difference between working, burst and over pressure
- What is the difference between vacuum and absolute pressure
- What does negative and positive gauge pressure mean
- Measuring negative pressure using a positive differential pressure range
Related Technical Terms
- Absolute Pressure
- Barometric Pressure
- Bidirectional
- Burst Pressure
- Compound Pressure Ranges
- Differential Pressure
- FS – Full Scale
- Gauge Reference Pressure
- Hydrostatic Pressure
- MSL – Mean Sea Level
- Negative Gauge Pressure
- Overpressure Protection
- Rangeable
- Reference Pressure
- SG – Sealed Gauge
- Static Line Pressure
- Suction Pressure
- Vacuum
- Vented Cable
- Vented Gauge
