7-Sonic-Nozzle-Test

High Accuracy Sonic Nozzle Test Rigs

Basics of Sonic Nozzle TestingThe Meter Under Test and the Volume Reference Standardare located in a temperature controlled test room and air isdrawn from the room through both the Meter Under Testand the reference standard in series. Temperature stabilityis very important in measurement so the meter under testshould always be in the test room for a suitable period oftime to acclimatise.2 – Landis+Gyr – Antony Cockshott

Critical Flow Venturi Nozzles ISO9300+Critical Flow Venturi Nozzles are designed andmanufactured to have a smooth, geometricallysymmetrical internal shape with a very smooth roundedinlet section converging to a minimum throat area anddiverging along a pressure recovery section.+The Critical Flow Venturi Nozzles are designed to therequirements as detailed in the Standard ISO9300.3 – Landis+Gyr – Antony Cockshott

Critical Flow Venturi Nozzles ISO93004 – Landis+Gyr – Antony Cockshott

Flow through a Sonic NozzleAs a gas acceleratesthrough the Nozzle, itsvelocity increases and itsdensity decreases.The maximum velocity isachieved at the throat,the minimum area, whereit just reaches Mach 1 orcritical flow.The flow then slowsagain as pressure isrecovered in the exitdivergent section of thenozzle.5 – Landis+Gyr – Antony Cockshott

Sonic Flow at the Throat+ By decreasing the pressure P2downstream eventually a point isreached where the velocity of the airreaches the local speed of sound (MachNumber =1) at the Throat.+ This occurs when P2

Flow Rate Under Real Conditions+ A nt = Cross sectional area of the sonicnozzle+ C d’ = Discharge coefficient (ISO9300)+ C * = Critical flow function (Air) (ISO9300)+ P o = Stagnation pressure (Abs) sonicnozzle inlet+ R=Universal Gas Constant+ M=Molar Mass (Air)+ T o =Stagnation Temperature (Abs) atsonic nozzle inlet+ C R = Critical flow coefficient+ Zo=Compressibility Factor at upstreamstagnation conditions7 – Landis+Gyr – Antony Cockshott

Air is Not an Ideal Gas+ The compressibility factor Z expresses the deviation from the idealgas laws at a given pressure and temperature for air Z≠1.+ The density of air varies as the temperature and moisture content inthe air varies. When the temperature increases the higher molecularmotion results in an expansion of the volume and thus decreasing thedensity.+ For the sonic nozzle equations in ISO9300 we need to know thecompressibility factor Z of the humid air and the density of the humidair (at the given Pressure and Temperature).+ The equation of the density of moist air requires input values for airtemperature, pressure and relative humidity (or dew-pointtemperature).8 – Landis+Gyr – Antony Cockshott

Sonic Nozzle Calculations9 – Landis+Gyr – Antony Cockshott

Repeatability of a Sonic Nozzle ProverSonic Nozzle Repeatability Data20/10/2011 to 15/03/20120.30.20.10-0.120/10/201122/10/201124/10/201126/10/201128/10/201130/10/20111/11/20113/11/20115/11/20117/11/20119/11/201111/11/201113/11/201115/11/201117/11/201119/11/201121/11/201123/11/201125/11/201127/11/201129/11/20111/12/20113/12/20115/12/20117/12/20119/12/201111/12/201113/12/201115/12/201117/12/201119/12/201121/12/201123/12/201125/12/201127/12/201129/12/201131/12/20112/01/20124/01/20126/01/20128/01/201210/01/201212/01/201214/01/201216/01/201218/01/201220/01/201222/01/201224/01/201226/01/201228/01/201230/01/20121/02/20123/02/20125/02/20127/02/20129/02/201211/02/201213/02/201215/02/201217/02/201219/02/201221/02/201223/02/201225/02/201227/02/201229/02/20122/03/20124/03/20126/03/20128/03/201210/03/201212/03/201214/03/2012-0.2-0.3Elster RVG Meter G16 Qmax, Repeatability ± 0.043% Test EquipmentSNIP4 Uncertainty ± 0.22%, 5 months 100 total tests.10 – Landis+Gyr – Antony Cockshott

Uncertainty of a Sonic Nozzle Prover+ Sources of Error- Pressure Measurement- Temperature Measurement- Relative Humidity (or Dew Point or Density)- Time Measurement- Analogue / Digital Converters- Initial Certification (Reference Flow Rate)+ Uncertainty typically ± 0.20 to 0.25 %11 – Landis+Gyr – Antony Cockshott

Sonic Nozzles in Combination ( 2 n -1 )2^10-1=1023, 2^7-1=127, 2^6-1=63, 2^5-1=3112 – Landis+Gyr – Antony Cockshott

Domestic Sonic Nozzle Rig x 3+ Testing Domestic Gas Meters, 3 Stations+ The CAPS utilises five installed critical flow venturinozzles for 0.5, 1.2, 1.6, 4.7, 6, 7.3, 8 and 9.6 m 3 /h+ First placed in operation March 2009+ Best Measurement Capability +/-0.20 %+ Capable of testing gas meters up to 10 m 3 /h+ CAPS has an automatic clamping fixture specificallydesigned for meter models 610, 602, 750 & 1010+ Fixed mass flow rate for a specified temperature,pressure and nozzle geometry when sonic velocity isachieved+ Regulation 13 Certified to the National MeasurementAct 196013 – Landis+Gyr – Antony Cockshott

Domestic Sonic Nozzle Rig x 314 – Landis+Gyr – Antony Cockshott

Sneak Peek – MAPS New Domestic Sonic Nozzle Rig15 – Landis+Gyr – Antony Cockshott

Sneak Peek – MAPS New Domestic Sonic Nozzle Rig16 – Landis+Gyr – Antony Cockshott

Sonic Nozzle Industrial Prover No 1+ The SNIP utilises six critical flowventuri nozzles that can be used in63 various flow rate combinations.Capable of testing gas meters up to25 cubic metres per hour+ First placed into operation April 2008+ Regulation 13 Certified in accordancewith the National Measurement Act1960. Best Measurement CapabilityEstimated +/-0.2 %.+ Fixed mass flow rate for a specifiedtemperature, pressure and nozzlegeometry when sonic velocity isachieved.+ Meters AL425 @ 2” Diff, AL425,AC630 @ ½” Diff.+ The testing is fully computerised withresults stored on a remote server.+ Automated test data formats &delivery17 – Landis+Gyr – Antony Cockshott

Sonic Nozzle Industrial Prover No 118 – Landis+Gyr – Antony Cockshott

Sonic Nozzle Industrial Prover No 2+ Designed to do AL425,630,800 & 1000+ SNIP No 2 utilises seven critical flowventuri nozzles that can be used in 127various flow rate combinations+ Fixed mass flow rate for a specifiedtemperature, pressure and nozzlegeometry when sonic velocity is achieved+ Capable of testing gas meters up to 61cubic metres per hour+ Best Measurement Capability+/-0.25 %+ The testing is fully computerised withresults stored on a remote server.+ Automated test data formats & delivery+ Placed into operation May 2009+ Regulation 13 Certified to the NationalMeasurement Act 196019 – Landis+Gyr – Antony Cockshott

What is SNIPW7 ?+ The SNIPW7 System is a meter verification prover used to test industrial gasmeters. SNIPW7 Systems are the next generation of test equipment which isbuilt upon the original SNIP (Sonic Nozzle Industrial Prover) system developedin 2008. However the SNIPW7 System has been upgraded with the followingfeatures;- Compatibility with Microsoft Windows7 Operating System- Compatibility with Microsoft .Net Framework (VB.Net)- Allow testing of meters with high frequency outputs 0.00084 to 5000 Hz- Allow testing of meters using 1 or 2 Transfer Standard Meters (TSM)Typical Flow rates typically 200 to 6,500 m 3 /h- Allow up to 10 sonic nozzle combinations (original SNIP was limited to 7)- 10 sonic nozzle combinations= Potentially 1023 flow combinations !- Typical Flow rates 0.5 to 500 m 3 /h- Fully automated test procedures- Regulation 13 Certified to the National Measurement Act 196020 – Landis+Gyr – Antony Cockshott

SNIPW721 – Landis+Gyr – Antony Cockshott

SNIPW722 – Landis+Gyr – Antony Cockshott

Meter Details23 – Landis+Gyr – Antony Cockshott

Test Setup Screen – Meter Details24 – Landis+Gyr – Antony Cockshott

Test Screen25 – Landis+Gyr – Antony Cockshott

Test Finish Screen26 – Landis+Gyr – Antony Cockshott

Manual Control Screen27 – Landis+Gyr – Antony Cockshott

Any Questions?+ Thanks for listening, and have a nice day!30 – Landis+Gyr – Antony Cockshott