Instrumentation & measurement
Differential-pressure flow sensors
Differential-pressure flow sensors infer flow from the pressure drop across a primary element such as an orifice plate, venturi or pitot tube. A manometer or differential pressure transmitter reads that difference, which is then converted to a flow rate.
Overview
Differential-pressure (DP) flow measurement is one of the longest-established methods. A primary element restricts or samples the flow, creating a pressure difference that rises with the square of flow velocity, and a secondary instrument reads that difference. For simple checks, a U-tube manometer filled with a suitable liquid shows the difference directly in millimetres of water column, for example across pitot tubes or orifices in air-handling and ventilation ducts. For continuous indication and control, a DP transmitter provides an electrical signal for square-root extraction and display.
Selecting the right differential-pressure flow sensor
Choose the primary element by fluid, line size, allowable permanent pressure loss and the flow range needed, since DP methods have a limited turndown. Then choose how the difference is read: a manometer for local visual checks, or a transmitter for remote indication and control. Impulse-line arrangement, fluid temperature and the compatibility of wetted materials also need checking.
Range overview
- Types and variants
- U-Tube Manometers
- Materials and grades
- Aluminium Casing with Acrylic Front (Manometer)
- Size range
- Manometer Height 7 to 27 Inches
- Pressure / temperature
- Manometer Scales 250-0-250 mm H2O and 750-0-750 mm
Exact specifications depend on the variant, material and size. Confirm ratings and certification against the datasheet or with our engineers before ordering.
Applications
- Differential Pressure Across Pitot Tubes and Orifices
- Air Handling and Ventilation Systems
Information that speeds up a quotation
Share what you know. Anything you are unsure of can be marked “not known” — our engineers will help confirm it.
- Fluid
- Flow min
- Flow max
- Size
- Accuracy
- Pressure
- Temperature
- Signal
- Power
- Certification
Need a datasheet?
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Frequently asked questions
What information do you need to quote a differential-pressure flow measurement?
Send the fluid, the minimum, normal and maximum flow, operating pressure and temperature, line size, the allowable pressure loss, and whether you already have a primary element such as an orifice or pitot tube. Say whether a local reading is enough or an electrical signal is needed, and give the output and power supply required for a transmitter.
When is a U-tube manometer enough?
A U-tube manometer suits local, periodic readings of small pressure differences, such as checking air flow across a pitot tube or orifice in an air-handling or ventilation duct. It needs no power and is read directly against its scale. Where a reading must be recorded, alarmed or used for control, a differential pressure transmitter is the better choice.
Ready to specify differential-pressure flow sensors?
Send the details you have — quantities, sizes, drawings or a part number. Unknowns are fine.