leak detection repair
Bubble Method Leak Detection
Find the exact spot of a leak with bubble solution.
9 steps4 criticalLimit 10 min
Steps
- 1Bring the system or the section under test up to the test pressure in your procedure; dry nitrogen is a commonly used test gas for pressure testing refrigerant lines
- 2Choose a bubble solution made for refrigerant leaks, or soapy water if your course allows it
- 3Put on eye protection and gloves before handling the solution
- 4Critical stepSpray or brush an even coat onto every fitting, joint, braze and service port
- 5Watch each joint for bubbles; large leaks bubble at once, slow leaks can take seconds or minutes
- 6Mark every spot where bubbles form
- 7Critical stepWipe the tested areas with a damp cloth
- 8Critical stepRecord the method, each leak location, and the result (and the gas and pressure used, if your employer requires it)
- 9After the repair, retest the repaired joint before any refrigerant is added back
What graders are watching for
Tips
- A bubble test shows where a leak is, but only if gas is pushed through it. Very slow leaks can take minutes to show, so a clean first look is not proof of a tight joint.
- Use a solution made for refrigerant leaks. One manufacturer says solutions made for natural gas are thinner, cling less to the pipe, and can be blown off before the leak is found.
- Nitrogen is exempt from the Part 82 venting ban; refrigerant is not. Never purge or release refrigerant to the air to make a test easier.
Common mistakes
- Testing only the joints you suspect.
- Moving on before slow leaks have had time to bubble.
- Using a thin natural-gas solution that runs off the pipe.
- Using a pressure drop alone to locate a leak; it says a leak exists, not where.
Practice this skill
Practise the sequence in the app with critical-step highlighting and a rationale for each step.
Start your 7-day free trial7 days free, then $9.99/month. Cancel anytime.
Sources and how we check them: How we verify.