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
Hastelloy diaphragm -100 to 50 kPa g range manometer - Small manometer device with membrane protected against corrosive material (chemicals) and which we would prefer to be covered with Hastelloy steel. 
5000 psi WECO® 1502 pressure transmitter and loop indicator - Loop powered display for mounting on a wall in hazardous area connected to a pressure transmitter with hammer union WECO™ 1502 process connection
Featured absolute reference pressure sensor products
DMP457 Marine Approved Pressure Transmitter - Marine approved stainless steel diaphragm pressure transmitter with 4-20mA current loop output for shipbuilding in ranges from 100mb to 600 bar gauge or absolute.
Power generation OEM engine oil pressure sensor with 75bar abs range and RS485 - Robust RS485 absolute pressure sensor for OEM engine oil monitoring in power generation. 0-75 bar range, G1/4 male process connection, and M12 electrical connector. 9-32V DC supply.
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
Monitoring vacuum depression in food powder drying towers with a low range dp transmitter - DP transmitter for precise vacuum measurement and control for coconut powder drying towers to ensure consistent product quality.
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.
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
Suction Pressure Sensors - Suction pressure sensors for measuring negative gauge reference pressure. Select pressure sensors for measuring the level of pressure below ambient atmospheric pressure.- Monitoring vacuum depression in food powder drying towers with a low range dp transmitter - DP transmitter for precise vacuum measurement and control for coconut powder drying towers to ensure consistent product quality.
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
Borewell water level sensor for 100m water height - Low cost solution to measuring the water level in a borewell with a water height of as much as 100 metres above the submerged sensor
Aquaculture submersible freshwater level & temperature transmitter - Use this submersible dual output transmitter for monitor or controlling the water level and temperature of freshwater ponds & tanks used in aqua farming.
Related Help Guides
- Measuring vacuum with negative gauge or absolute ranges
- What is the difference between gauge and absolute pressure measurement
- What is the difference between vacuum and absolute pressure
- Measuring negative pressure using a positive differential pressure range
- Not reading zero when pressure is vented to atmosphere
- What is difference between working, burst and over pressure
- What does negative and positive gauge pressure mean
Related Technical Terms
- Bidirectional
- Burst Pressure
- FS – Full Scale
- Gauge Reference Pressure
- MSL – Mean Sea Level
- Negative Gauge Pressure
- Reference Pressure
- SG – Sealed Gauge
- Static Line Pressure
- Vented Cable
- Vented Gauge
Related Product and Application Guides
Barometric Pressure
Overpressure Protection
Hydrostatic Pressure
Suction Pressure
Absolute Pressure
Compound Pressure Ranges
Related Application Questions and Answers
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