orifice meter

orifice meter
Name	Orifice meter
Type	Differential pressure flowmeter
Invented	19th century
Used for	Measurement of volumetric and mass flow rates

orifice meter is a primary flowmeter that infers volumetric or mass flow from a differential pressure generated by a flow constriction. It is widely used across hydrocarbon, chemical, water, and power industries and appears in engineering projects, pipeline systems, and process plants. The device is associated with classical hydraulic research, industrial standards, and a lineage of flow measurement techniques.

Introduction

An orifice meter creates a pressure drop by inserting a restriction into a pipeline, translating that drop into flow via empirical and theoretical relations. The instrument’s practice connects to the legacies of Isaac Newton, Daniel Bernoulli, Leonhard Euler, George Gabriel Stokes, and experimental traditions found in institutions such as Massachusetts Institute of Technology, Imperial College London, Technical University of Berlin, ETH Zurich, and University of Cambridge. Industry adoption grew through organizations like American Petroleum Institute, International Organization for Standardization, American Society of Mechanical Engineers, British Standards Institution, and National Institute of Standards and Technology.

Operating Principle

Operation relies on principles articulated in Bernoulli's principle and the conservation laws associated with Leonhard Euler and Daniel Bernoulli. A constriction produces a higher velocity and lower static pressure; the differential pressure is measured upstream and downstream and used in a discharge equation developed from empirical factors introduced by researchers linked to Reynolds number effects studied by Osborne Reynolds. The flow coefficient and discharge coefficient are evaluated using correction factors from experimental programs reminiscent of work at National Physical Laboratory (United Kingdom), Delft University of Technology, and French National Centre for Scientific Research.

Design and Components

Basic components include a plate or nozzle with a sharp edge, a pipe run, tapping points, differential pressure taps, and a differential pressure transmitter such as those manufactured by Emerson Electric, Siemens, ABB Group, and Honeywell International. Construction materials reference standards from ASTM International and involve metallurgy common to suppliers like Carpenter Technology Corporation and Vallourec. The geometry follows guidelines promulgated by ISO standards and committees in API practice, and component tolerances are verified in test facilities at institutes such as Sandia National Laboratories.

Installation and Installation Effects

Correct installation requires straight-pipe run lengths, orientation, and upstream disturbance control; guidance is given in documents from API, ISO, and ASME. Upstream fittings such as elbows specified by Victaulic Company or valves from Embraco-class suppliers cause asymmetric flow profiles similar to phenomena investigated at Los Alamos National Laboratory. Installation near compressors like those from Siemens Energy or pumps from Sulzer affects profile recovery distances studied in wind-tunnel and pipe-loop campaigns at National Renewable Energy Laboratory and university laboratories. Field practice involves site engineering from firms such as Bechtel, Fluor Corporation, and TechnipFMC.

Performance, Accuracy and Uncertainty

Performance depends on diameter ratio, flow regime, and discharge coefficient databases developed by ISO and ASME. Uncertainty analyses reference statistical methods championed at Bell Labs and error propagation approaches used by NIST. Typical uncertainties in industrial applications are influenced by instrumentation from Yokogawa Electric Corporation and calibration services by organizations like Bureau Veritas and Intertek Group. High-Reynolds-number flows and two-phase mixtures produce deviations addressed in studies at Shell research centers and BP laboratories.

Applications and Industry Use

Orifice meters are prevalent in custody transfer metering in oil and gas pipelines operated by companies such as ExxonMobil, Chevron, TotalEnergies, Eni, and ConocoPhillips. They appear in water distribution managed by utilities modeled on Thames Water and New York City Department of Environmental Protection practices, in power plants designed by General Electric, and in chemical plants from BASF and Dow Chemical Company. Process control integrations connect to distributed control systems from Schneider Electric, Rockwell Automation, and Yokogawa.

Standards and Calibration

Key standards include those published by API, ISO, ASME, and national metrology institutes including NIST and NPL. Calibration is performed in flow laboratories operated by National Physical Laboratory (United Kingdom), NIST, PTB (Physikalisch-Technische Bundesanstalt), and commercial labs such as UL-accredited calibration houses. Traceability chains often reference intercomparisons organized by entities like OIML and regional metrology organizations.

Limitations and Alternatives

Limitations include permanent pressure loss, sensitivity to upstream disturbances, reduced accuracy with multiphase flow, and wear from abrasive fluids—considerations highlighted in technical reviews from SINTEF and DVGW. Alternatives encompass meters that avoid a permanent pressure drop or better handle complex fluids: ultrasonic meters from GE Measurement & Control, coriolis meters by Endress+Hauser and KROHNE, vortex meters from Yokogawa, and differential-pressure elements such as venturi meters favored in projects by Fluor Corporation and Bechtel.

Category:Flow measurement devices