Let-by and tightness test

LET-BY, STABILISATION AND TIGHTNESS TEST HELPER

Edition 4 helper for live-gas let-by, temperature stabilisation and tightness testing. For qualified engineers only.

Scope: This helper covers the IGEM/UP/1B Edition 4 live-gas procedure. Edition 4 is in effect. Edition 3 may run alongside it until 30 September 2026 and is withdrawn from 1 October 2026. If the installation is not connected to a live gas supply, use the applicable air-test procedure in Appendix 3 instead.

A) Installation Volume

Installation volume (m³) Fuel gas type Natural Gas LPG / Air LPG Test arrangement Select the test arrangement New installation, no appliances connected, or appliances isolated Existing installation with appliances connected and not isolated Known or suspected gas escape

This decides whether Edition 4 requires no perceptible movement or permits use of the connected-appliance pressure-drop table.

Smell of gas during the test Select an answer No smell detected Smell detected or suspected Use saved installation volume from the IGEM calculator

Checking saved installation volume...

B) Equipment Used

Equipment type Water gauge Digital manometer - 1 decimal point Digital manometer - 2 decimal points

Select the equipment used. This sets the let-by fail threshold.

C) Let-by Check

For Natural Gas, LPG/Air and LPG, adjust the pressure to between 7 and 10 mbar and observe the let-by period for 1 minute.

Enter both readings after completing the one-minute let-by period.

D) Temperature Stabilisation

Select the fuel and installation details to obtain the applicable Edition 4 tightness test pressure.

Allow 1 minute for pressure and temperature to stabilise. Do not continue until a stable reading is obtained.

E) Tightness Test

Continue for a further 2 minutes at the correct test pressure.

Enter the tightness test start and end readings to calculate the pressure drop and support assessment against current IGEM guidance.

F) Stopwatch

Use this to time the let-by, stabilisation or tightness test stage. You can still use your own stopwatch separately if preferred.

START TIMER STOP TIMER RESET TIMER

Procedure confirmation

One-minute let-by test completed Stabilised for at least one minute and continued until the reading was stable Further two-minute tightness test completed

G) Results

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Disclaimer:
This Edition 4 helper is intended only to support qualified engineers carrying out live-gas let-by, temperature stabilisation and tightness testing. It does not replace the complete IGEM/UP/1B Edition 4 procedure, formal training, manufacturer instructions or professional judgement. It must not be used for an air test or as the sole basis for declaring an installation safe. The user remains responsible for checking the current standard and following all required safety procedures.

Copyright © TomKat Gas Training Ltd. All rights reserved. This tool may not be copied, reproduced or distributed without permission.