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
16 bar, 200°C steam pressure transmitter and gauge - Combined pressure transmitter and indicator in one package with the option for use with high temperature media such as steam at 200°C
CIP cleaning low concentration acid solution pressure sensor with 100 inH2Og range and 4-20mA output - Hygienic CIP pressure sensor with 316L stainless steel flush diaphragm and food grade oil filling for low concentration acid solutions in food and beverage processing. 0-100 inH2O range, 4-20mA output, dairy pipe DN25 connection.
Featured absolute reference pressure sensor products
20 kg/cm² range 5Vdc output pressure transducer for potable water - Potable water pressure transducer with a 0 to 5 volts output and 0 to 20 kg/cm² absolute pressure range
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.
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 hot and cold aisle containment in datacenters using a differential pressure transmitter - Low range differential pressure transmitter with a local display was used to maintain precise room pressurization in a mission-critical datacenter environment for improved thermal management.
Balancing air pressure in marine engine rooms with a low range dp sensor - Low-range bidirectional differential pressure sensor helps maintain the critical air balance in a sealed vessel engine room, ensuring optimal engine combustion and ventilation performance.
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
- Measuring negative pressure in hospital construction zones with a low range differential pressure transducer - Low-range differential pressure transmitter provides the resolution needed to verify negative pressure in hospital construction vestibules, ensuring containment of dust and airborne contaminants.
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
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
LMK807 Plastic Submersible Level Transmitter - IP68 mid range pressure transmitter for measuring the level of highly contaminated and aggressive liquid media with a body made from PP-HT.
Dock bridge tidal flap submersible level transmitter with sea water compatibility - Marine bronze submersible level transmitter for reliable depth measurement in dock bridge applications with tidal flaps.
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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