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
10 bar g steam pressure transmitter - High temperature pressure transmitter for use with steam pressures up to 10 bar gauge.
5 psi steam boiler pressure sensor with 300°F cooling element and 1/4″ npt male - This 5 psi steam pressure sensor with 4-20mA output is designed for high-temperature applications, with 1/4" NPT male and integrated 300°F cooling element for reliable steam pressure monitoring in autoclaves & sterilizers.
Featured absolute reference pressure sensor products
33X High Accuracy Digital Output Pressure Sensor - High precision pressure transducer with an accuracy of 0.05% full scale with a RS485, USB or RS232 digital interface for connecting to a PC.
35X Flush Diaphragm Digital Output Pressure Sensor - Highly accurate digitally compensated pressure transducer with G1/2 male flush pressure port.
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
100 Pa bi-directional range differential air pressure transmitter - Bi-directional low range 4 to 20 milliamp differential pressure transmitter covering an air pressure range from -100 to +100 pascals, for cleanrooms, isolation rooms, and filter monitoring.
DPT100 Modbus RTU RS485 Differential Pressure Sensor - The DPT 100 is a high-accuracy differential pressure transmitter designed for fast test processes in leakage and flow measurement applications where rapid response time and high sampling rates are essential
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
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.
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
Underwater 50 metre sea depth 4-20mA output sensor - All titanium underwater sensor for measuring seawater depth with a measurement range of 0 to 50 metres providing a 4 to 20 mA output signal.
Screw-in 2m height onboard marine vessel diesel tank base mount level sensor - Monitor fuel levels in marine diesel tanks with the DMK 458 hydrostatic level sensor. Marine-approved and designed for viscous fluids.
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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