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
-0.9 to +2.2 bar g Autoclave pressure transducer - This autoclave pressure sensor provides accurate pressure monitoring in medical, pharmaceutical, and industrial sterilization applications. Its robust design and integrated cooling element ensure reliable performance in demanding environments.
Chlorine dioxide (ClO2) resistant 20 bar PVDF pressure sensor - The dmk331 pressure transmitter offers reliable pressure measurement in chlorine dioxide applications up to 20 bar. Features PVDF, ceramic diaphragm, and FKM seals wetted parts for enhanced chemical resistance.
Featured absolute reference pressure sensor products
DS200P Sanitary Low Range Pressure Gauge, Switch and Sensor - All in one electronic switch, gauge and sensor designed specifically for use in the food, drink and biomedical industry for measuring process pressures.
SSPT Subsea Wet-Mateable Electrical Connector Pressure Sensor - This stainless steel ceramic sensing diaphragm based subsea connector pressure sensor provides a unamplified ratiometric millivolt output or an amplified analogue output signal corresponding to ranges from 0…1 bar (14.50 psi) up to 400 bar ( 5800 psi).
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
20 Pa DP range 0-10V output air pressure sensor for building management use - A low range 20 Pa range differential pressure sensor, ideal for monitoring filters, ventilation ducts, and HVAC systems in commercial and residential buildings.
Airflow and chamber pressure measurement for a portable modbus data acquisition trolley - Differential pressure sensor and a analogue signal to Modbus RTU RS-485 converter provided a flexible solution for measuring bidirectional pressures from a test chamber and an orifice plate on a mobile test rig.
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
DMP343 Low Range Pneumatic Pressure Sensor - DMP343 pneumatic pressure sensor for measuring very low range pressures on pneumatic control systems, heating, ventilation and air conditioning systems (HVAC) .- 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.
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
Zone 0 ATEX borehole water level sensor for flammable atmospheres - Monitor water levels in hazardous area boreholes with this ATEX-approved transmitter. 100m depth, Zone 0.
ATM/N Titanium Submersible Hydrostatic Pressure Transmitter - All Titanium submersible pressure transmitter for measuring the hydrostatic level of leachate, brackish water or sea water. Ranges from 1 up to 250mWC.
Related Help Guides
- 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
