Job and test context
This STS assistant is configured for domestic dwellings with installation volume no greater than 0.035 m³. IGEM/UP/1B itself may cover other qualifying installations, but this tool does not assess them. The engineer must confirm pressure, pipe bore, meter capacity, installation volume and all other scope conditions against the full standard.
Installation volume
Choose the actual pipe material and nominal size, then enter its measured length. The reference volume per metre is filled in automatically. Add every run in the section being tested; use a verified manufacturer value for unlisted pipework. STS must check these preset reference values against its final licensed Edition 4 copy before live use.
The metric/imperial choice describes the meter register. A listed meter fills in its internal capacity in m³ regardless of the register type. For any other meter use verified manufacturer data in m³, never the cumulative consumption reading. Where actual valves and fittings volume is known, enter that value. Otherwise, the 10% fallback is applied to the calculated pipework volume. The selected amount is added to pipe and meter volumes. Select “No meter” when excluded and enter 0.
Test readings and checks
Before the timed test
Confirm the checks required for this arrangement using the controlled procedure.
On-site test helper
Guided test timer
One stage at a time. Set up the gauge and valve as prescribed before you press Start.
- Let-by · 1 min
- Stabilise · 1 min
- Tightness · 2 min
Record gauge readings
Enter the readings observed during each stage. The pressure drop is calculated from the tightness readings; gauge movement remains your observation.
Enter all four readings to document the test stages.
Use the procedure and timings in STS’s controlled copy of the standard. A 0.25 mbar reading on a water or suitable digital gauge, or 0.2 mbar on a one-decimal digital gauge, can count as “no perceptible movement” under ISU 133 Edition 2; the engineer must assess the instrument and actual movement. This form does not infer gauge movement from a number.
Calculation and prompts
A satisfactory tightness test is required immediately before admitting fuel gas for purging. Maintain good ventilation, prevent gas accumulation and control ignition sources except the intended burner ignition. Keep the purge area attended and follow the complete procedure, including every branch and final appliance checks.
Method threshold uses installation volume, before × 1.5. Quantity alone does not authorise a purge. NG method reference: BPEC Module 6, pages 43–46 (Edition 3); IGEM’s Edition 4 FAQ confirms that the purging procedure is unchanged.
STS GasCheck · Tightness & Purge Calculator • Reference: IGEM/UP/1B Edition 4 and Gas Safe Register Industry Standard Update 133 (Edition 2). Calculation aid only. Its output is not a gas safety certificate, test result, approval or sign-off. A competent gas engineer must verify the inputs, use the full current standard, perform the physical test and determine and record the outcome. Job entries are saved on this device only; clear the form after the job. Contact details submitted through the separate welcome form are held by STS. For a suspected gas escape, follow the full investigation and unsafe-situations procedures.