Sonic nozzles (4 pieces) with nominal flow rates 0.5 m3/h, 16 m3/h, 32 m3/h, 75 m3/h will be used to compare primary low-pressure test facilities.The laboratories should carry out the calibration using their common procedures.The procedure described in PTB Testing Instruction Volume 25: "Gas meters – Test rigs with critical nozzles" is recommended to be used. The parameters QV,20,tr,1000[L/h] and cpE[-] are required to be determined for each sonic nozzle.
Each laboratory will be responsible for the transfer of the sonic nozzles to the next laboratory. No other costs are expected.
- Test gas: air
- Upstream sonic nozzle pressure: near atmospheric
- Test temperature: (19.5 ÷ 22.5) °C