The history of DP flow measurement goes back to at least the 17th century, though the measurement of flow using nozzles goes back to Roman times. At the beginning of the 17th century, Torricelli and Castelli arrived at the concepts that underlie differential pressure measurement today: that flowrate equals velocity times pipe area, and that the flow through an orifice varies with the square root of the head. In 1738, Bernoulli developed his famous equation for flowrate calculation.
The development of primary elements for use in measuring DP flow also began about this time. Pitot presented a paper on the use of the “Pitot tube” in 1732. Venturi published his work on the Venturi principle for measuring flow in 1797. However, Venturi’s work was not developed for commercial application until 1887 when Clemens Herschel used Venturi’s work to develop the first commercial flowmeter based on it. In 1898, Herschel published his paper, The Venturi Water Meter.
Max Gehre received one of the first patents on orifice flowmeters in 1896. The first commercial orifice plate flowmeter appeared in 1909 and was used to measure steam flow. Shortly thereafter, the oil and gas industries began using orifice plate flowmeters due to ease of standardization and low maintenance. In 1912, Thomas Weymouth, of the United Natural Gas Company, did experimental work on the use of orifice flowmeters to measure natural gas. Weymouth used pressure taps located one inch upstream and one inch downstream of a square-edged orifice. The Foxboro Company licensed Weymouth’s work and used it as a basis for building orifice meters shortly after this time.
The increased use of orifice meters captured the attention of several engineering organizations. These included the American Gas Association (AGA), the American Petroleum Institute (API), and the American Society of Engineers (ASME). The National Bureau of Standards (NBS) also became involved in this research. In 1930, a joint AGA/ASME/NBS test program was able to generate a coefficient-prediction equation based on extensive tests. In 1935, tests performed at Ohio State University in conjunction with the National Bureau of Standards served as the basis for flow equations that have been used by the AGA and ASME since that time.
Work in the United States was combined with European work in the late 1950s and resulted in the issuance of ISO Standards R541 for orifices and nozzles and R781 for Venturis. Standard R541 was issued in 1967 and R781 was released in 1968. At about the same time, an ASME Fluid Meters Research Committee began a study to reevaluate the Ohio State data and to add new data on coefficients. The results were issued in an ASME Fluid Meters Report in 1971.
J. Stolz proposed a universal orifice equation in 1975. His idea was to combine the Ohio State data into a single dimensionless equation that could be used for corner, flange, and D- and D/2 taps. He presented his equation in a paper in 1978. This equation appears in the ISO Standard 5167, published in 1980, which combines the previously published R541 and R781 standards into a standard for DP flow. The ASME Fluid Meters Research Committee adopted the ISO 5167 standard in 1981. In 1995, this standard was developed into the ASME MFC-3M standard for all orifice, Venturi, and nozzle flowmeters.