Fuel Line Pressure Testing Details?

[bshawco]

The KAI includes detailed instructions (and a kit) for pressure testing the fuel tank. But, when it comes to pressure testing the fuel lines, not so much.

I don't yet have the fuel pump that ships with the engine. Therefore, I believe I need to bridge the IN & Out lines of the bulkhead fittings, the fuel pump and the tank.

One of those bridges will include a pressure gauge and Schrader valve.

Then I pressurize the system and test each fitting with soapy water.

Someday, I'll need to re-test with the fuel pump and engine connected.

I'm wondering:

1) Is all that correct?

2) Should I use a Home Depot quality pressure gauge and related fittings?

3) What pressure should I use for a 12sI fuel system?

Thanks in advance.

 

[John-G]

Below you will find links to my blog ... I've included all the posts (the good and bad) .... if you read it all you will see I changed testing strategy and also changed the pressure gauge from inches of water to PSI.

I ended up looping the the main fuel line to the return line aft of the fuel pump and capped off the fuel return line at the firewall shelf with a cap .... this way I could test both runs at the same time. Compressed air was put into the lines at the gascolator using a Schrader valve on a brass T that the pressure gauge screwed into.

Think I used 10 PSI for testing. Note:The pressure will vary depending on ambient temps. If the shop is warm and you pressure the system then come back in the morning when the shop is cold, you will see what appears to be a loss of pressure ... wait until the shop warms back up before determining if there is a leak or not.

http://www.dogaviation.com/2014/04/pressure-testing-fuel-lines-begins.html

http://www.dogaviation.com/2014/04/rv-12-fuel-line-pressure-testing.html

http://www.dogaviation.com/2014/04/fuel-line-testing-encouraging.html

http://www.dogaviation.com/2014/04/fuel-line-pressure-test-completed.html

Happy building.

 

[TS Flightlines]

Brad----if you are talking about the rigid tubes, the normal fuel pressure on a 912IS is 40-46 psi. If you want to test each tube there are several ways.
1) dont worry about 'blowing up' the tube---46 psi is way below the burst pressure of the tube. Back in the early days, I made a pressure tester from an old parts washer container. Bulkhead fitting in the side with a few adapters for the different sizes that might be necessary. A supply hose in the tank, just because a rigid tube might be odd shaped. Inlet air, regulated to the desired pressure.
I eventually changed that to a hydraulic ram pump with a large reservoir to develop a bunch more pressure for doing hose work. I would put whatever in some sort of container to capture posslble fluid leaks from flares, etc. Saves the mess. You dont have to have something exotic like the testers we use, but the simple home build ones serve the same purpose.

Tom

 

[BobbyLucas]

I pressure-tested my tank ages ago when I built it and it still leaked when I put gas in the first time recently. I "tested" the lines by fueling up and running the pumps - no leaks.

Is there some reason I need to do an air pressure test, or is that just something to do early on while repairs are easier?