Category
Liquid Differential Pressure Transmitters
Differential pressure measurement for water and other liquids, across pumps, filters and heat exchangers.
A liquid differential pressure transmitter shows how hard a pump is working and when a strainer is blocking, using a sensor built for water pressure, not the pascal ranges used for air. The Beck 988 transmitter covers 0 to 2, 0 to 6 or 0 to 10 bar, and the Beck 908 switch covers 40 to 1000 mbar.
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Selection guide
Liquid Differential Pressure Transmitters Guide
How a liquid differential pressure transmitter works
The Beck 988 uses a ceramic (Al2O3) measuring cell across two ports to sense the pressure drop caused by a pump, strainer, filter or heat exchanger. Because liquids carry far more force than air at the same differential, the sensor and its seals are built for bar-range pressures and for continuous contact with water or process liquid, rather than the low pascal ranges used on air DP transmitters.
How to choose a liquid differential pressure transmitter
- Continuous monitoring: the Beck 988 transmitter gives 0 to 2, 0 to 6 or 0 to 10 bar ranges, with a 4 to 20 mA two-wire or 0 to 10 V / 4 to 20 mA three-wire output, for plotting pressure drop over time.
- Simple alarm: the Beck 908 switch, listed under differential pressure switches, trips a contact at 40 to 200 mbar or 150 to 1000 mbar, for a blocked-filter or dry-run alarm without continuous readout.
- Medium: both suit liquid and gaseous, non-flammable, non-aggressive media as standard; the 908 is available with materials for aggressive media when specified.
- Temperature and connection: the 908 handles -10 to +80 °C through brass G 1/8 connections.
For air and gas circuits, see air differential pressure transmitters.
FAQ
Common questions
Transmitter or switch for a water filter or strainer?
A switch, such as the Beck 908, gives a simple blocked-filter alarm at one set point. A transmitter, such as the Beck 988, shows the pressure drop continuously, so you can trend it and plan cleaning before the alarm trips, rather than reacting after it does.
What pressure ranges does the Beck 988 liquid transmitter cover?
0 to 2, 0 to 6 and 0 to 10 bar, with a 4 to 20 mA two-wire output or a 0 to 10 V / 4 to 20 mA three-wire output, using a ceramic (Al2O3) measuring cell suited to continuous liquid contact.
Can the Beck 908 switch handle aggressive liquids?
Yes, when specified with suitable materials. Standard versions suit non-aggressive, non-flammable liquids and gases; tell us the liquid and its concentration and we'll confirm the right diaphragm and connection combination for your service.
How is liquid differential pressure used to protect a pump?
A DP switch or transmitter across the pump's suction and discharge, or across a strainer ahead of it, alarms if the pressure drop shows the pump is running dry or the strainer is blocking, before the pump is damaged by cavitation or loss of flow.
What's the difference between a liquid and an air differential pressure transmitter?
A liquid DP transmitter, such as the Beck 988, is built for bar-range pressures and continuous contact with water or process liquid. An air DP transmitter is built for much smaller pascal ranges and needs a more stable zero, since air and gas differentials are typically far lower than liquid ones.
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