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
High sulphuric acid content resistant 16 bar g 4-20mA water pressure sensor - This 4-20mA pressure sensor with PVDF, ceramic, and FKM construction is designed for water with high sulfuric acid content up to 10%. Ideal for chemical processing and wastewater treatment.
20 barg 4-20mA output 200degC steam pressure sensor for process control use - A hi-temp media 200°C/392°F max gauge pressure sensor for process control use to measure pressure of steam over a range of 0 to 20 bar g from the 1/2 BSP flush diaphragm male process connection, and sending the corresponding 4-20mA signal through the M12 connector electrical 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.
300 mmHg absolute vacuum pressure transducer with 10 volts output - Absolute pressure transducer for precise vacuum measurement. 0-300 mmHg range, 0-10V output, high accuracy.
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.
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.
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
DPS Low Differential Pressure Transmitter - Ultra low differential pressure transmitter for HVAC applications with 4-20mA current loop or amplified voltage output signal in pressure ranges from 0.1 mb up to 1 bar differential. 
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).
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
200m deep well pump water level sensor, switch & display - Protect your deep well pump with thhis submersible level transmitter and wall mounted indicator and alarm. This system provides reliable water level monitoring and pump protection at depths of up to 200 meters.
Low power consumption fuel tank level sensor - Reliable and accurate fuel level measurement in remote locations. Battery-powered with low power consumption.
Related Help Guides
- What is the difference between sealed gauge and vented gauge reference?
- Measuring vacuum with negative gauge or absolute ranges
- What is the difference between gauge and absolute pressure measurement
- Pressure device not reading zero? Get troubleshooting tips
- What is difference between working, burst and over pressure
- What is the difference between vacuum and absolute pressure
- Can you measure vacuum using a gauge pressure range
- 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
