Live from 1 October 2026

Understand and test the new IGEM/UP/1B Edition 4.

Same tightness test, new way to judge it. Watch the 5 minute guide, then let the Tightness Test app time the test, read your U-gauge from a photo, work out the volume, the allowed drop and the purge, and write the record.

Get the app Watch the guide

For Gas Safe registered engineers and their apprentices.

Tightness Test, IGEM/UP/1B Edition 4: the 5 minute guide

The 5 minute guide to Edition 4

Get it on Google Play Download on the App Store

What changed

The test is the same. How you judge it is new.

Edition 3 withdrawn

Edition 3 was withdrawn on 30 September 2026. Edition 4 applies to every test from 1 October 2026.

Drop set by installation volume

The allowed drop now depends on the installation volume (pipework, fittings and meter), not the meter size.

Retest the pipework alone

Appliances connected and a small drop? Isolate them and retest the pipework on its own.

Why now

Every gas customer needs a test to the new standard. Be the one who does it.

The emergency service won't do it for them.

Cadent and the gas transporters attend, make safe, and leave

After a smell of gas or a cut-off, the customer is told to get a Gas Safe engineer to test and reinstate. That is your call to take.

Edition 4 is new to everyone.

Landlords, agents and homeowners are asking

A tightness test to IGEM/UP/1B Edition 4, with a record they can keep, is a job you can offer today: on every service, safety check and reconnection.

Many houses will show a drop.

A small drop you'd once have passed is now a job

Under Edition 4 any movement on the gauge means isolating the appliances and re-testing the pipework. Expect to find leaks on your daily services and safety checks that need tracing and fixing: repair work you'd have walked past before.

Done in minutes, recorded properly.

Timed, judged and written up on your phone

The app does the Edition 4 sums and the paperwork, so the test pays its way on every visit and the record goes to the customer before you leave.

The Tightness Test app

The maths done for you, on site.

Reads your U-gauge

Take a photo at the start and the end. The app finds the level and reads it to the nearest 0.25 mbar; zoom in and correct it if you need to.

Judged the moment you enter the drop

Pass, isolate-and-re-test or fail against the Edition 4 table, with the next job spelled out. Test 1, 2, 3 all on the record.

Volume and purge

Pipe lengths, fittings and meter give the installation volume; purge volume 1.5 × IV and whether to purge to air or to ignition.

Gas rate calculator

Reads the meter from a photo, times the minute, gives m³/h and the heat input gross and net.

The test record

Let-by, every test, purge, leak detection fluid check and result on page one; your gauge photos on page two. Save the result on its own or issue the certificate.

The Gas Volume Calculator screen in the Tightness Test app

A look inside

What it looks like on the job.

Scroll sideways. Screens from the app, test figures from a demo account.

Home: start with a U-gauge, import a gauge result, or the calculators

Setup and let-by: an imported result fills the readings in

The reader finds the level on your photo and reads it

Tightness test: the verdict the moment the readings are in

The gauge moved: isolate and re-test, with the next job spelled out

Pipework-only re-test passed, risk assessment, final result

The record: your gauge photos on page two

Gas rate calculator: m³/h and the heat input

How it works

See it working, one short video per part.

Silent, captioned videos. The app videos are also in the app under Learn.

Get it on Google Play Download on the App Store

The 5 minute guide to Edition 44:50

What changed from Edition 3, how the drop is judged by volume, the re-test, the purge. Watch this first.

The whole app in four minutes4:03

Import an electronic gauge result1:09

Paste the printout from your gauge app: let-by, stabilisation and the tightness test fill in. Then the certificate.

Read a water U-gauge from a photo0:38

Take a photo at each reading. The app finds the level and reads it to 0.25 mbar; zoom in and correct it if you need to.

When the gauge moves1:06

The verdict the moment you enter the drop, the installation volume under it, the pipework-only re-test and the risk assessment.

The result and the record0:46

Save the result on its own or issue the certificate: page 1 the record, page 2 your gauge photos with the readings drawn on.

Gas rate calculator0:24

Two meter readings a minute apart, read from a photo or typed: m³/h and the heat input, gross and net.

Five steps on every job.

1. Setup and let-by

Gas, what is being tested, let-by and stabilisation, each timed.

2. Tightness test

Two minutes. Photo the gauge or type it. The verdict shows at once; the volume only if the gauge moved.

3. Purge and leak detection fluid

Purge by volume, repeat test, LDF on every disturbed joint.

4. Client and installation

Who and where, with the client's signature on the phone.

5. Result

PASS or FAIL against Edition 4. Save the result, or issue the certificate as a PDF.

Get the app.

Download the Tightness Test app and do your next test to Edition 4.

FAQ

Who is it for?

Gas Safe registered engineers, and apprentices working under one at a registered business. Every new account is checked against the Register before it opens.

What does UP/1B cover?

Installations up to 0.035 m³, pipe up to 35 mm, meter up to 16 m³/h. Above that, IGEM/UP/1A.

Does it replace my judgement?

No. It is an aid; you remain responsible for testing to the current IGEM/UP/1B.

What does it cost?

Nothing to download or use at the moment. If that changes we will tell you first, and your records stay yours.

Terms and privacy, in short

For Gas Safe registered engineers and their apprentices (learning only, no certificates); accounts are checked against the Register.
You stay in charge: the app is an aid, the test and the decision are yours.
Your records are yours. Photos are read on your phone; meter photos are not kept.
Your data is stored with Google Firebase, encrypted, never sold or shared.
Delete your account in the app and everything goes with it.

Full terms of use Privacy policy

Last updated 7 October 2026 · hi@flueprint.app