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Tuesday, April 28, 2020 | History

2 edition of Primary calibrations of critical flow venturi nozzles in high-pressure gas found in the catalog.

Primary calibrations of critical flow venturi nozzles in high-pressure gas

T J S. Brain

Primary calibrations of critical flow venturi nozzles in high-pressure gas

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Published by National Engineering Laboratory in East Kilbride .
Written in English


Edition Notes

Statementby T.J.S.Brain and J.Reid.
SeriesN.E.L. report no.666
ContributionsReid, J.
The Physical Object
Paginationiv, 18p. :
Number of Pages18
ID Numbers
Open LibraryOL13712417M

How High Accuracy is reached with Sonic Nozzles for Gas Calibrators Feb 15 Read Times. No electronic signal measurement or flow regulation are needed as flow condition are blocked by gas physics conditions of the critical flow. The simple setup of a sonic nozzle calibrator is key in reducing potential sources of uncertainty.


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Primary calibrations of critical flow venturi nozzles in high-pressure gas by T J S. Brain Download PDF EPUB FB2

This Standard applies only to venturi nozzles in which the flow is critical. Critical flow exists when the mass flow rate through the venturi nozzle is the maximum possible for the existing upstream conditions. At critical flow or choked conditions, the average gas velocity at the nozzle throat closely approximates the local sonic velocity.

The Premature Unchoking Phenomena of Critical Flow Venturis Richard Caron, Charles Britton, and Tom Kegel,ASME Fluids Engineering Division Summer Meeting Abstract: The choking pressure ratio (CPR) for a Critical Flow Venturi (CFV) is defined as the ratio of the maximum permissible exit pressure to the inlet pressure that can exist across the venturi and still.

ISO (E), Measurement of Gas Flow by Means of Critical Flow Venturi Nozzles. Castillon, “Mise au point d’un etalon de debit constitue detugeres en regime sonique,” by: 2. A “sonic nozzle” (also known as “Critical Flow Venturi” or “Critical Flow Nozzle”) is a flow meter that can be used as a calibration standard for gas flow meters or any flow measurement device.

By design, sonic nozzles are a constant volumetric flow meter. After calibration, the corresponding nozzles still offer the same very reliable means of gas metering, however, as long as they are employed within their specifications.

The flow fields in nozzles with Reynolds numbers below the range given by the standard (Re=×10 3 –×10 4) have been investigated by von Lavante et al. [5] experimentally as well as by: 2. The flow rate was measured using a mass flow meter composed of multiple critical flow Venturi nozzles and was adjusted to a set value by controlling the pressure of the gas upstream of the nozzles.

This document describes NIST's high pressure natural gas flow calibration service (NGFCS). Flow calibrations are conducted offsite at the Colorado Experimental Engineering Station Incorporated (CEESI) in Garner, Iowa.

A parallel array of nine turbine meter working standards (TMWS) are used to calibrate customer flowmeters over a flow range from m 3 /s to 9 m 3 /s at nominal pressures Cited by: 2. Flow Stability of Critical-Flow Venturi Nozzles. Series of CFD (computational fluid dynamics) simulations were performed for Critical-Flow Venturi Nozzles (CFVN) to investigate the stability of transonic and supersonic shock structures forming within the nozzle geometries.

5 and mm throat diameter nozzles with ISO form. KEYWORDS: Critical Nozzle, Discharge Coefflcient, Crltical Flow. INTRODUGION A Venturi sonic nozzle is a well-accepted and utilized f1ow measurement device in most high-pressure gas test facilities.

It is accurate and Its measurement uncertainty 15 well documented In the ISO standard [1 ]. TheseFile Size: 2MB. In the ejector primary nozzle (1) motive fluid accelerates and expands () (Figure ) from the high pressure p 1 to the pressure p 2 which is lower than secondary flow suction pressure.

The flow at the outlet of the primary nozzle is usually supersonic, and the nozzle profile is convergent-divergent. Currently, state-of-the-art commercial calibrations of high-pressure gas flowmeters are performed with uncertainties that range between % and %, depending on pressure and flowrate.

These measurement capabilities are traceable to primary standards using several steps in which the flowrate range and pressures are increased.

Uncalibrated flowmeters include a theoretical performance curve similar to the calibrated performance curve but based on ideal theoretical performance data. Sonic Nozzles (Sonic Venturi, Critical Flow Nozzle, Critical Flow Venturi) designed to ASME MFC-7M Specifications. Available for most gases.

Critical Flow Nozzles (Sonic Nozzle, Sonic Venturi, Critical Flow Venturi) designed to ASME MFC-7M Specifications. Available for most gases.

Air flow ranges from pounds per second ( scfm) and up. Most any end connection. Venturi Flowmeters (Sub-Sonic Venturi, Venturi Tube, SAO, Meter Run) designed to ASME MFC-3M Specifications. Flow nozzle accuracy is typically 1% AR, with a potential for % AR if calibrated.

While discharge coefficient data is available for Reynolds numbers as low as 5, it is advisable to use venturi nozzles only when the Reynolds number exce Flow nozzles maintain their accuracy for long periods, even in difficult service.

Critical flow Venturi nozzle A critical flow Venturi nozzle (CFVN) is a convergent-divergent restriction inserted into a system and is used to determine the mass flow rate of a gas flowing through a system. In the critical flow Venturi nozzle the gas flow accelerates to the critical velocity at the throatFile Size: KB.

7.A.1 Design. With the intention of reducing the uncertainty in flow measurement using Venturi tubes, Venturi tubes of different shapes (ones with longer convergents, ones without sharp corners or even ones with curved convergents) were tested (Reader-Harris et al.).

The first design was of a Venturi tube with a machined convergent of angle Author: Michael Reader-Harris. Primary calibrations are considered to have measured the trapped discharge coefficient, whereas nozzles in applications, where a constant pressure ratio is applied for a long time, have a discharge coefficient inherent to the pressure ratio; inherent and trapped coefficients can differ by –%.Cited by: 3.

For the flow setting of air and pure gases for recurring calibration tasks of flow meters critical nozzles according to standard DIN EN ISO are an ideal, long-time stable transfer standard.

They are very efficient when used with nozzle galleries. Flow nozzles provide reliable, accurate flow measurement and long-term repeatability, particularly in steam applications with high flow velocities.

Control of the media mix In the blower systems of combustion furnaces, the adjustment of the fuel-air ratio to the firing capacity is controlled by Venturi tubes. RITTER Multiple Sonic Nozzle Calibration System Calibration service facilities that must maintain multiple types and sizes of meters, require the ability to calibrate a wide range of?ow rates.

RITTER wet test meters measure from 1 to 18, litres/hr. Dry gas meters can measure from 40 tolitres/hr. This file presents the national references developed by LNE-LADG (Associate Laboratory for Gas Flow Measurement) to ensure the traceability of high-pressure gas flow measurements.

The main feature of the traceability chain maintained by LNE-LADG is the use of critical flow Venturi nozzles as transfer standards. The Laboratory has used these nozzles since the early s. We developed a new nozzle manifold that reduced the uncertainty of flow calibrations from % to as low as % for flows of air up to kg/s (43 L/min at reference conditions of kPa and K).

The nozzle manifold also reduces the time required to complete calibrations by a factor of Author: Aaron N. Johnson, Chunhui Li, John D. Wright, Gina M. Kline, Christopher J. Crowley. ISO specifies the geometry and method of use (installation in a system and operating conditions) of critical flow Venturi nozzles (CFVN) used to determine the mass flow-rate of a gas flowing through a system.

It also gives the information necessary for calculating the flow-rate and its associated cturer: Multiple. Distributed through American National Standards Institute. Venturi nozzles enable the measurement of flow rates in pipelines by reference to changes in fluid pressure when passing through a constricted area.

With Venturi flow meters, you will see notably better pressure recovery compared to orifice-style flow meters. This causes a less pressure drop across the venturi i.e. the differential pressure is less.

Low DP means low permanent pressure loss. Venturi can be used for a wide variety of applications that include air, water, vapor, steam, gas, chemical substances, sludge and slurry applications. B rain, T.J.S. and M ac D onald, L.M.

Evaluation of the performance of small-scale critical flow venturi using the NEL gravimetric gas flow standard test facility. Fluid Flow Measurement in the Mid s. Edinburgh: HMSO,pp.

[28] B rain, T.J.S. and R eid, J. Primary calibration of critical flow venturis in high-pressure gas. RITTER Multiple Sonic Nozzle Calibration System Calibration service facilities that must maintain multiple types and sizes of meters, require the ability to calibrate a wide range of flow rates.

RITTER wet test meters measure from 1 to 18, litres/hr. Dry gas meters can measure from 40 tolitres/hr. Reaffirmed “Measurement of Gas Flow by Means of Critical Flow Venturi Nozzles” it is stated “The Venturi nozzles specified in this Standard are called primary devices.” Nozzles have been used for many years to prove natural gas meters.

Sonic Nozzles have a long history, are well documented and the formulas, although a bitFile Size: KB. In case of a nozzle, critical pressure may be defined as that maximum value of back-pressure, which gives maximum mass-flow-rate of the fluid is called critical pressure.

The above definition conforms with the fact that when back-pressure is decre. “Measurement of Gas Flow by Means of Critical Flow Venturi Nozzles” it is stated “The Venturi nozzles specified in this Standard are called primary devices.” Nozzles have been used for many years to prove natural gas meters.

Sonic Nozzles have a long history, are well documented and the formulas, although a bitFile Size: KB.

Choked flow is a fluid dynamic condition associated with the Venturi effect. When a flowing fluid at a given pressure and temperature passes through a constriction (such as the throat of a convergent-divergent nozzle or a valve in a pipe) into a lower pressure environment the fluid velocity increases.C d {\displaystyle C_{d}}: discharge.

Standards for Flow Nozzles, Venturies and Orifices. ISO specifies the geometry and method of use (installation and operating conditions) of nozzles and Venturi nozzles when they are inserted in a conduit running full to determine the flow-rate of the fluid flowing in the conduit. Unlike a “true Venturi meter” its high pressure sensation comes from a corner location on the inlet side of the center flange.

In order to claim that a tap senses “true static pressure”, the tap must sense pressure perpendicular to the axis of the flowing line fluid. Calibration Capabilities Below is a list of flow measurement calibration capabilities including NIST traceable calibration ranges for the facilities in Colorado and Iowa.

Both Colorado and Iowa facilities are accredited to ISO/IECas explained by the quality assurance program. The critical flow venturi nozzles dealt with can only beu sed within limitst hat ares pecified, for example nozzle throat to inlet diameter ratio and Reynolds number.

This Standards pecifies the geometry and methoodf use (installation and operating conditions) of critical flow venturi nozzles inserted in a system to determine the mass flow rate. (b) Flow Nozzles & Venturi Tubes - Flow Nozzles and Venturi Tubes are primary rate devices which will handle about 60% more flow than an orifice plate for the same bore under the same conditions, and can therefore handle higher velocity flows.

If a differential limit is chosen, then a smaller bore nozzle. ISO Measurement of gas flow by means of critical flow Venturi nozzlesCategory: w.

The characteristics of the position and form of the transition surface through the critical velocity are computed for flow through flat and round nozzles from subsonic to supersonic velocity. Corresponding considerations were carried out for the flow about profiles in the vicinity of sonic by: ISO specifies the geometry and method of use (installation in a system and operating conditions) of critical flow Venturi nozzles (CFVN) used to determine the mass flow-rate of a gas flowing through a ry: p.

All these sections when connected together, forms venturi flow meter. Venturi tubes gives accurate measurement of non-viscous fluids in clean as-well-as dirty fluids, manufactured strictly in accordance with ISO, ASME MFC- 3M, BS etc.

For critical measurement applications, wet calibration at reputed flow laboratories can be offered. NMI-Euroloop in Rotterdam does both liquid and gas flowmeter calibration, as does VSL.

Besides doing flow calibrations, VSL is the primary metrology laboratory for much of Europe. In the United Kingdom, the leading facility is the National Engineering Laboratory (NEL, ).

Another important facility in Dorsten, Germany is pigsar.Generally, the physical property generated by the primary flow element is more convenient to measure than the flow itself.

The properties of the primary flow element, and the fidelity of the practical installation to the assumptions made in calibration, are critical factors in the accuracy of the flow measurement.

The pipe Rd limitations have the same effect on the Universal Venturi Tube except that the minimum pipe Rd for the Universal Venturi Tube is 80, which means the flow rate can be quite a bit lower than the classical, yet still maintain the standard +/ percent accuracy that is the standard accuracy for the Universal Venturi Tube.

However.