Home > Flow Meter Calibrations > Critical Flow Venturis (CFV) and Sonic Nozzles Calibration and Training Services

Critical Flow Venturis (CFVs) and Sonic Nozzle Calibration & Training Services

Critical Flow Venturis and Sonic Nozzles are fluid flow measurement devices used in a number of industrial and scientific applications. Due to their high repeatability and reproducibility, they are considered to be very precise. Sonic devices operate on the principle that as fluid flows through the meter; the fluid accelerates as it approaches the throat. As the differential pressure increases, the velocity at the throat increases. When the velocity of the fluid reaches the local speed of sound, it is considered choked, sonic or critical. Once the flow has reached the critical state, increasing the differential pressure will not affect the fluid flow rate. Several components are important to a sonic device metering system; upstream and downstream piping, pressure sensors, temperature sensors and flow computers.

CEESI uses Critical Flow Venturis and Sonic Nozzles in our laboratories as transfer standards for calibration. When used in compliance with standards, it is not necessary to calibrate CFVs, and the typical uncertainty of a critical flow venturi metering system is on the order of 0.5-1.0%. The uncertainty of a sonic metering device can be reduced by calibrating the meter. Calibrated meters can have the uncertainty reduced to approximately 0.1%.

Meters from the following manufacturer’s have been calibrated and/or tested by CEESI:

Flow Systems
Fox Valve
PRC
Cox

Critical Flow Venturis (CFVs) and Sonic Nozzle Services

Calibration of Line Sizes from 3/4” to 36”
Typical uncertainties for CFV calibration are 0.5% in Colorado
Flow conditioner testing
Consulting on sonic device design
Consulting for sonic device flow measurement discrepancies
On-site auditing of sonic device setups
On-site sonic device validation
Training on fundamentals of sonic devices
Training on advanced sonic metering topics

Request a quote or contact us if you have questions about CFV/sonic nozzle calibrations.

Sample CFV/Sonic Nozzle Meter Calibration Certificates

Critical Flow Venturis (CFVs) and Sonic Nozzle Training Courses & Events

CFV/Sonic Nozzle Meter Publications & Papers

The following is a random sampling of documents relating to critical flow venturi (CFV) and sonic nozzle flowmeters from the Flow Measurement Technical Library . This library contains over 57,000 documents on flow measurement from NIST, ISHM, AGA, ISFFM, ASGMT, FLOMEKO, MSC and others; thousands of these documents are available for free download.

The Critical Flow Venturi: A Useful Device for Flow Measurement and Control
H. Hillbrath, 1971
Abstract: The critical flow venturi has outstanding advantages as a device for flow measurement and control. These include simple and predictable performancce due to its close approach to ideal, isentropic, one dimensional flow; low minimum choking pressure loss; and availability of supporting data on its application. however, this device has not recieved the degree of user acceptance it deserves, probalby primarily due to lack of a conveniant source of design data. This paper presents a summary of ess ....

Recent Advancements In Critical Flow Venturi Nozzle Technology
Walt Seidl and Emrys H. Jones, 1997
Abstract: Critical flow venturi/nozzles are precise flow rate measurement devices that are used in a number if industrial and scientific applications. This paper provides an overview of their application and recent developments in the art of operating a venturi /nozzle. Data presented in the last few years and in this forum provide an excellent base for which to begin a revision of the current ASME standard. For one skilled in the art, current critical flow nozzle standards provide ample guidance on the ....

Uncertainty Analysis of a Compressible Flowmeter Calibration Process
Tom Kegel, 1994
Abstract: This paper presents an uncertainty analysis of the process of calibrating a critical flow venturi with a primary flow standard using dry compressed air. The primary flow standard provides traceability to NIST through measurements of mass and time. The critical flow venturi is being calibrated foe use as a transfer standard. The uncertainty of the calibration process at a 95% level of confidence is estimated to be ±0.038%, data are presented that support this estimate.

The application of sonic (critical flow) nozzles in the gas industry.
P. Wright, 1993
Abstract: Sonic (critical flow venturi) nozzles have been used by some organizations as calibration standards for the accuracy testing of gas meters and have sometimes been used as flow transfer standards in inter-laboratory comparisons, but their routine application has been limited, possibly due to the lack of practical guidelines. The implementation of ISO 9300: 1990 ’Measurement of gas flow by means of critical flow venturi nozzles’ is discussed in relation to the practical applicati ....

Search the Flow Measurement Technical Library for papers on critical flow venturis and sonic nozzles.