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Differential Meter (Square Root Meter) Calibration Services

Differential meters refer to any meter that uses an obstruction in the flow to create a differential pressure. Any differential meter uses calculations based on the Bernoulli Principle. The Bernoulli Principle states that there is a relationship between the pressure in the pipe and the velocity of the flowing fluid. The primary differential producer provides a restriction in the flowing area that causes the fluid to accelerate. This acceleration can be measured by measuring the pressure drop across the differential producer. There are several important components of differential metering system. The actual meter is not just the differential producer, but includes the upstream and downstream lengths as well as any taps, thermowells, and flow conditioners. Other components in a differential measurement system include pressure and differential sensors (transducers), RTDs, and flow computers. All components of a differential flow measurement system must be evaluated when evaluating the system. Major benefits to using differential producing meters include reliability and repeatability.

Differential Meter Differential Meter

CEESI has been instrumental in the research and development of differential producing meters. For meters like orifice meters, venturi meters, and nozzles, there is not a need to flow calibrate each individual meter, provided the metering system is in compliance with applicable industry standards. The uncertainty associated with using these in compliance with a standard is on the order of 0.5 – 1.5%. Reduced uncertainties may be obtained by calibrating the actual meter run and/or system. For other meters, it is imperative to calibrate each individual meter. There is a standard for a testing protocol for differential type meters. API MPMS 22.2 provides guidance for what data needs to be taken in order to properly identify the performance of a differential producing meter.

CEESI has performed testing and calibration on the following meter types:
  • Brandt Tube™
  • Cameron NUFLO™ Differential Pressure Cone Meter™
  • Dynamic Flow Computers SmartCone Meter™
  • Elbow Meter
  • Laminer Flow Element
  • McCrometer V-Cone Meter™
  • McCrometer Wafer Cone Meter™
  • Pitot Tubes
  • Self Averaging Pitot Tube
  • Subsonic Flow Nozzle
  • Subsonic Venturi Meters
  • Rosemount Annubar Meter™
  • Rosemount Conditioning Orifice Plate Meter™
  • Veris Accelabar Meter™
  • Veris Verabar Meter™
  • Wedge Meters


  • Calibration of Line Sizes from 3/4” to 36” (full list of capabilities)
  • Capable of reaching flowrates over 1 Billion Cubic Feet per Day (BCFD) in Natural Gas
  • Typical uncertainties for differential meter calibration are 0.23% in Iowa, and less than 0.5% in Colorado
  • Flow computer testing and verification
  • API MPMS 22.2 Testing
  • Flow conditioner testing
  • Consulting on differential meter station design
  • Consulting for differential flow measurement discrepancies
  • On-site auditing of differential metering setups
  • On-site differential meter validation
  • Training on fundamentals of differential meters
  • Training on advanced differential metering topics
Request a quote or contact us if you have questions about differential meter calibrations.


We have invested considerable resources into creating the Flow Measurement Technical Library so that could be a useful resource to the flow measurement community. There are free downloadable papers and abstracts from a variety of organizations relating to differential meters. This library contains over 71,000 documents from organizations including NIST, ISHM, AGA, ISFFM, ASGMT, FLOMEKO, MSC, AGMSC, WGMSC, ASME, NEL, and others.

Search the Measurement Library for papers on differential meters.

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