Pick what you are testing. You get the test pressure, the hold time and the gauge range to use — with the code section each number comes from, so you can check it against your inspector before you pump up.
A 2 lb system runs at 2 psi. The test pressure is 1.5× this, and never below 3 psi.
The code holds a house for 10 minutes whatever its volume. Everything else is timed by how much pipe you are testing.
These are defaults, not a ruling. Local amendments override them, and some utilities ask for more. Confirm the required pressure, duration and gauge spec with your AHJ before the test.
For anything above a standard low-pressure system, the model code sets the test pressure as a multiple of what the piping will actually carry, with a floor underneath it:
| Input | Test pressure |
|---|---|
| Working pressure 0.25 psi | 3 psi1.5 × 0.25 = 0.4, so the 3 psi floor applies |
| Working pressure 2 psi (2 lb system) | 3 psi1.5 × 2 = 3, exactly the floor |
| Working pressure 5 psi | 7.5 psi1.5 × 5, above the floor |
Source for the rule: IFGC 2021 §406.4.1, mirrored in IRC §G2417.4. This page runs the same function the app runs on site, checked against the app's own test vectors.
The same job can have three different right answers depending on which code your state adopted and how it amended it.
| Rule set | Pressure and hold |
|---|---|
| IFGC / IRC, single-family dwelling | 3 psi · 10 minIFGC 2021 §406.4.1 & §406.4.2 · IRC §G2417.4 |
| IFGC / IRC, anything bigger | 3 psi · 30 min+Half an hour for each 500 ft³ of pipe volume or part of it, up to 24 hours — §406.4.2 |
| Uniform Plumbing Code jurisdictions | 10 psi · 15 minUPC §1213.3: not less than 10 psi for 15 minutes with no perceptible drop |
| Welded piping and systems over 14 in. w.c. | 60 psi · 30 minUPC §1213.3; NFPA 54 §8.1 as commonly adopted |
Several states amend these numbers further in their own plumbing or fuel-gas code. If your inspector quotes a number that is not on this page, the inspector is right — record the code edition you tested to on the certificate.
Air, nitrogen, carbon dioxide or an inert gas — and the code names oxygen as the one thing that must never be used. The fuel gas itself is not on the permitted list either. IFGC 2021 §406.2 · IRC §G2417.2
A manometer, or a dial gauge whose top of scale is no more than five times the test pressure — 15 psi for a 3 psi test. Many jurisdictions tighten this further, for example 0.1 psi increments or a range no more than twice the test pressure. IFGC §406.4
Whether a written test report is accepted instead of a witnessed test is up to the Authority Having Jurisdiction — it is an administrative decision in the adopted code, not a number in the gas chapter. Ask before the inspection.
One and a half times the working pressure, and never less than 3 psi. A house or a 2 lb system therefore tests at 3 psi; a 5 psi system tests at 7.5. Jurisdictions on the UPC ask for 10 psi instead, and that is the number most search results quote.
Ten minutes for a single-family dwelling or a system holding under 10 cubic feet. For anything larger the IFGC asks for half an hour per 500 cubic feet of pipe volume, or part of it, up to 24 hours. UPC jurisdictions use 15 minutes at 10 psi, and 30 minutes at 60 psi for welded or high-pressure work.
Oxygen — it is named outright in the code. The fuel gas itself is not permitted either: the list is air, nitrogen, carbon dioxide or an inert gas.
Yes. Air is the first medium the code lists, and it is what most tests use.
That is set by your jurisdiction and your licence, not by the model code — in most places the licensed installer performs it and the inspector witnesses or accepts a written report.
The calculator gives you the numbers. The app runs the hold on the wall clock, keeps the start and end gauge photos as proof, and prints the one-page certificate with these same citations on it.