How can you use a differential pressure measurement device to measure a negative pressure if it has been factory configured to measure a positive pressure range without making any adjustments to the electronics or the signal output?
Finding a pressure sensor to read negative pressure can be difficult since the vast majority of pressure measurement devices are only available with positive ranges as standard, since most applications require a positive pressure range, and therefore manufacturers understandably focus on the most popular pressure ranges for their product range.
Although manufacturers will often consider a custom configuration for measuring negative pressure, this could cause a delay to delivery and an extra cost compared to the standard pressure range configuration.
Featured differential pressure measurement products
901 Prescal Pressure Switch Specification and Data Sheet - Adjustable pressure switch for monitoring overpressure (5 mbar up to 12 bar), vacuum (-5 down to -700 mbar) or differential pressure (5 to 50 mbar) of liquid, gas and aggressive media. The pressure switch uses a scaled adjustment knob to enable the adjustment of trip and reset pressure without the use of a screwdriver. Page Contents Temperature Range […]
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.
There is a much simpler and convenient solution to measuring negative pressures. A differential pressure measurement device has two separate pressure connections so that the difference in pressure between the two connections can be measured. One connection will be marked as High (Hi) or Positive (+), and the other as Low (Lo) or Negative (-).
Typically when measuring positive pressures, the Low side connection would be open to ambient air pressure, and the High side connection would be connected to the positive pressure to be measured.
If you want to measure negative or suction pressure instead, you can reverse the connection, so that the High side connection is open to ambient air pressure, and the Low side connection is connected to the vacuum pressure. As the vacuum increases, the greater will be the difference in pressure between the Low and High side.
As an example, a 0 to +100 mbar differential pressure range will become a 0 to -100 mbar differential pressure range simply by reversing the connections.
Featured differential pressure measurement 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.
DPT200 High One Side Overload Differential Pressure Sensor - DP transmitter for measuring pressure difference between two pressure points which can tolerate up a very high overload pressure independently on either the positive or negative side port or both together at the same time.
Featured differential pressure measurement products
Low-range air pressure monitoring in raised floor plenums using a wireless SNMP gateway - This application required a robust method for maintaining constant pressure in a data center's underfloor plenum. The solution combines a sensitive ±25 Pa differential pressure sensor with a wireless transmitter and an Ethernet gateway that provides SNMP protocol support for seamless integration with existing network monitoring systems.- 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.
Related Help Guides
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- Measuring vacuum with negative gauge or absolute ranges
- Measuring the difference in air pressure between rooms
- What is the difference between vacuum and absolute pressure
- What does negative and positive gauge pressure mean
- Measuring vacuum as a negative gauge pressure using a dp sensor
- Measuring liquid level in a tank using a dp sensor
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Related Technical Terms
- Differential Pressure
- Dry/Dry
- Negative Gauge Pressure
- Static Line Pressure
- Suction Pressure
- Vacuum
- Wet/Dry
- Wet/Wet
Related Online Tools
- DP Flow Transmitter Output Calculator
- High and Low Side Pressure to Differential Pressure Calculator
- Suction Pressure to Vacuum Calculator
