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
MEK solvent compatible pressure transducer with 5 bar g range and 0-5 volt output - Methyl Ethyl Ketone solvent compatible pressure transmitter with a 0-5V dc analogue output for measuring pressures from 0 to 5 bar gauge.
Trichloroethylene compatible 100 mbar Ex pressure transmitter - Intrinsically safe pressure transmitter with ceramic diaphragm for trichloroethylene compatibility. Ideal for low-pressure measurement in hazardous areas.
Featured absolute reference pressure sensor products
Near-atmospheric pressure transmitter for hazardous gas test chambers - Intrinsically safe pressure transmitter configured for a narrow, sub-atmospheric range to safely monitor dangerous gases in a test chamber.
DMP333 High Range Precision Pressure Transmitter - The DMP 333 is a stainless steel 316L wetted parts pressure sensor for high pressure ranges on applications such as hydraulic test benches, presses, and hydraulic actuation.
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
Detecting water intake blockage on submerged reservoir intake screen using two sensors - Discover a robust solution for measuring head loss and detecting ice blockages on remote water intake screens. Learn how dual submersible pressure transmitters with 4-20mA outputs overcome long-distance signal transmission challenges in reservoir monitoring.
Low Range DP Sensors - Low range differential pressure sensors for measuring very small pressure differences.
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
IMP Ceramic Strain Gauge Pressure Transducer - Ceramic strain gauge pressure transducer with a 2mV/V or 10mV/V output signal in pressure ranges from 1 bar up to 700 bar gauge or absolute.
Vacuum suction sensor & wall mount digital readout with switched contacts - Vacuum suction sensor that can provide a digital readout and a switched contact when the pressure gets too high
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
Water level transmitter for monitoring sump pit water depth - Low range water depth sensor with a 4-20mA output, for connecting to a PLC to control a sump pump and submerging into a pit to monitor the level
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
- Determining the hydrostatic pressure range for a tank level sensor
- Measuring vacuum with negative gauge or absolute ranges
- What is the difference between gauge and absolute pressure measurement
- Not reading zero when pressure is vented to atmosphere
- 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
- 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
Low Pressure Range
Barometric Pressure
Overpressure Protection
Suction Pressure
Absolute Pressure
Compound Pressure Ranges
Hydrostatic Pressure
Related Application Questions and Answers
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