- Instrument Type
- 4-20mA Transmitters
- 0-5, 10V Transducers
- mV/V Sensors
- Digital Sensors
- Absolute Sensors
- ATEX Transmitters
- Calibration Pumps
- Calibrators
- Compound Ranges
- Digital Gauges
- Digital Manometers
- Digital Readouts
- DP Transmitters
- Indicators - Pressure
- Liquid Level Sensors
- Loggers - Pressure
- Loggers - Liquid Level
- Suction Pressure Sensors
- Switches
- Accessories
- Your Application
- Absolute Reference
- Air/Pneumatics
- Barometric/Atmospheric
- Certificates & Approvals
- Data Logging
- Differential
- Electrical Signal
- Flush Diaphragm
- Gauge Reference
- High Accuracy
- High Frequency Response
- High Range
- High Temperature
- Intrinsically Safe
- Leak Testing
- Level Measurement
- Low Ranges
- Measuring Range
- Media Compatibility
- Miniature
- OEM Design
- Overpressure Protection
- PC Interfacing
- Pressure Calibration
- Process Connection
- Testing
- Sensor Technology
- Submersible
- Temperature & Pressure
- Vacuum
- Water Level
- Water Pressure
- Your Industry
- Manufacturers
Gauge Reference Pressure
Gauge reference pressure is a pressure measured relative to atmospheric or barometric pressure.
The most used pressure reference is gauge pressure which is signified by a (g) after the pressure unit (e.g. 30 psi g), and means that the pressure measured is the total pressure minus atmospheric pressure. There are two types of gauge reference pressure which are called vented gauge (vg or g) and sealed gauge (sg).
A vented gauge pressure transmitter for example allows the outside air pressure to be exposed to the negative side of the pressure sensing diaphragm, via a vented cable or a hole on the side of the device, so that it always measures the pressure referred to ambient barometric pressure.
Thus a vented gauge reference pressure sensor should always read zero pressure when the process pressure connection is held open to the air.
A sealed gauge reference is very similar except that atmospheric pressure is sealed on the negative side of the diaphragm. This is usually adopted on high pressure ranges such as hydraulics where atmospheric pressure changes will have a negligible effect on the accuracy of the sensor so venting is not necessary.
This also allows some manufacturers to provide secondary pressure containment as an extra precaution for pressure equipment safety if the burst pressure of the primary pressure sensing diaphragm is exceeded.
There is another way of creating a sealed gauge reference and that is to seal a high vacuum on the reverse side of the sensing diaphragm. Then by adjusting the electronics the output signal is offset by 1 bar so the pressure sensor reads close to zero when measuring atmospheric pressure.
A sealed gauge reference pressure transducer will never read exactly zero because atmospheric pressure is always changing and the reference in this case is fixed at 1 bar.
Site Last Updated: 04/02/12
Glossary - Find explanations for terminology used in specifying and using pressure instruments
Pressure Conversion - Look up conversion factors or select a conversion table for a particular pressure unit
Pressure Measuring Guide - Collection of guidance notes for sourcing, setting up and using pressure measurement equipment
News Articles - Archive of application notes, product releases and technical information
Answers - Search for questions already answered or submit a new question about a pressure measurement topic or product
Pressure Sensor Specification - Select parameters with PSAT to generate a spec for your own use or to submit as an enquiry
Product Finder - Choose multiple product and application types to filter out a suitable product
- 27/03/09 : Measuring vacuum pressure with negative gauge or absolute pressure ranges
- 29/11/08 : What is the difference between a pressure transducer and a transmitter
- 15/09/08 : What is the difference between gauge and absolute pressure measurement
- 17/08/08 : What to consider when selecting a differential pressure sensor
- 10/02/08 : What affects the performance of low pressure sensors
- 19/01/08 : Supply voltage and load resistance considerations for pressure transmitters
- 06/01/08 : Measuring liquid level in a sealed tank with a hydrostatic pressure sensor
- 18/09/07 : Interpreting specifications of pressure sensor accuracy