Tightness & Purge Calculator

Job and test context

I confirm the installation is within IGEM/UP/1B Edition 4 scope: installation volume up to 0.035 m³, pipework up to 35 mm (R1¼), meter up to 16 m³/h, and MOP up to 2 bar (natural gas 21 mbar / LPG 37 mbar nominal).

Gas and meter

Choose the fuel gas and the meter included in the test. Choose "No meter" when testing from an AECV.

Pipework

Add each run by material, size and measured length. For hidden runs, use the largest size fitted and round the length up.

+ Add another pipe run

Use the actual valves and fittings volume where you can work it out; the 10% allowance is the fallback.

What are you testing?

Your limit for this test

Test procedure

1. Turn off all appliances and the ECV. Connect the gauge at the meter test point.
2. Let-by test: raise the pressure to 7–10 mbar, close the ECV and watch for 1 minute. Any rise means the ECV is letting by.
3. Raise the pressure to the test pressure. Allow 1 minute for temperature to stabilise.
4. Tightness test: record the pressure, then watch for 2 minutes and record the final pressure.
5. Ask whether anyone can smell gas. Any smell of gas must be traced and repaired, whatever the gauge shows.

Before you start

Let-by test (1 minute)

Temperature stabilisation (1 minute)

Raise to the test pressure, then watch for at least 1 minute. Don't start the test until the reading is steady.

Tightness test (2 minutes)

Pipework-only retest

The drop is within the limit for this installation. Isolate the appliances and repeat the test on the pipework. The pipework must show no perceptible movement.