The industry’s most accurate and reliable flow meters


We maintain the industry's largest team of in-house hydraulic engineers to test, analyze, and calibrate our meters to deliver the verifiable accuracy that our customers require.  With accuracy performance margins of +/-0.25% lab calibrated and +/-0.5% bench calibrated, and years of accumulated performance verification, we stand by our products.


With no moving parts and precision manufacture, our Halmi Venturi HVT flow primaries regularly achieve decades of reliable service.  Relying on the Bernoulli principle, our engineers have finely calibrated our meters measure pressure differentials of fluids through simple sensors and special geometry. 

This elegance of the differential design means that there is little opportunity for system malfunction. This achievement is evidenced by our exemplary record of reliability as the largest supplier of Venturi flow meters to the industry.

Primary Flow Signal (PFS) engineers lead the industry in research and analysis of flow primaries, including the development of numerous technical studies and patented elements.

To learn more about our technology and how it works, please see our pages on:

Without proper calibration, a meter's accuracy can be impaired, and this miscalculation can cause inefficiency and loss for your system.

PFS can deliver the precise, independently verified, customized calibration that your application demands. And, as the premier provider of high accuracy flow metering solutions in North America for over 30 years, we apply a vast breadth and depth of knowledge and expertise to each individual system. 

PFS offers independent laboratory calibration services for any type of flow element:

  • Define and quantify accuracy of an existing installation
  • Develop flow calibration plan that will be useful to the client
  • Provide a new Operation and Maintenance Manual for the system and the new calibrated certified device
  • Provide flow calculations for flow elements that are no longer supported by their original manufacturers

Please select from the list below:

The HVT (Halmi Venturi Tube) is proven the most reliable and accurate flow metering technology for continuous pressurized line fluids. As the most thoroughly performance-substantiated flow measurement product in the world today, the HVT improves on the Classical Venturi in cost and accuracy for measuring.

HVTs are available prefabricated or cast-in-place in a variety of materials, shapes, and sizes; as single- or bi-directional flow meters. PFS also specifies and manufactures using non-traditional materials use to adapt to any needs.


  • Ideal for gas or liquid line fluids, including contaminated, highly viscous, or solids-bearing media
  • No annular chambers, therefore no plugging
  • Linear standard discharge coefficient of 0.99 (from approximately 75,000 pipe Reynolds number and above)
  • Standard accuracy of +/0.50% (2 Sigma)
  • Line size availability from 1 inch up to 180 inches
  • No downstream installation effect; minimal upstream effect


accuracy photo 1

16.0 Inch HT-PI Flow Primary

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HVT-PI Flow Meters