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
Tire fabrication curing press wireless pressure monitor - Engineers in tire manufacturing required a method to wirelessly monitor low-range gauge pressure inside a curing press. A solution combining a wireless transmitter with a high-gain remote antenna provided the necessary signal integrity for process control.- HVAC chilled water wireless pressure monitoring in BMS - Upgrade your Building Management System with a reliable wireless pressure sensing system. This case study explores the implementation of a 0-10 bar gauge wireless transducer and receiver pair for HVAC applications, highlighting the 'plug and play' installation and long-term, low-maintenance operation.
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.
Marine approved atmospheric pressure sensor - Marine-approved pressure sensor for atmospheric pressure measurement on ships. 4-20mA output, 800-1200mbar range.
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
Differential Pressure Transmitters - Differential pressure transmitters for measuring the DP of fluids and gases across particle filters and along a length of pipe to monitor flow.
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.
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.
DS210 Combined Low Pressure Switch, Indicator and Sensor - Low range three in one pressure switch, pressure indicator and pressure sensor for use on pneumatics and HVAC applications.
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
25m borehole submersible pump level indicator and control switch with level sensor - I am hoping to use a borehole where the pump is about 25m below the surface. I would like the pump to operate automatically by switching on when the water has returned to about 14m below ground level and off at about 20m below the ground.
LMP305 Borehole Level Transmitter - Submersible stainless steel pressure transmitter ideal for geotechnical surveying with a 19mm diameter for measuring hydrostatic water level in bore-holes.
Related Help Guides
- Not reading zero when pressure is vented to atmosphere
- Measuring vacuum with negative gauge or absolute ranges
- What is the difference between gauge and absolute pressure measurement
- 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
- 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
