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  #1  
Old 06-13-2022, 11:37 AM
UNCRV UNCRV is offline
 
Join Date: Aug 2020
Location: NC
Posts: 37
Default Fuel line test

On the Rv12is I wanted to get an idea of what the community thought on this topic. I decided to test a couple of the fuel lines before I went much further on the build so I capped three ends and put a pressure gauge in the system as well as a valve and inflated the system to 50 psi. I found several leaks using dish soap and tightened those connections and pumped the system back up. After 24 hours it lost 10 psi. Is this acceptable or do I need to chase this down?
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  #2  
Old 11-29-2022, 08:58 AM
UNCRV UNCRV is offline
 
Join Date: Aug 2020
Location: NC
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After I figured out the problem with this was the cheap pressure gauge I got the res of the lines installed. Is there any problem with pressurizing the entire system with the fuel pumps installed using air (minus the tank which is out of the plane at the moment). I donít see why it would cause a problem with the pumps but wanted to check here first.
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  #3  
Old 11-29-2022, 09:31 AM
Freemasm Freemasm is offline
 
Join Date: Nov 2017
Location: Orlando
Posts: 949
Default At a minimum

Have someone with a fire extinguisher stand fire watch for you. There's a recent, well known case for such.
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  #4  
Old 11-29-2022, 09:56 AM
UNCRV UNCRV is offline
 
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Oh I meant using compressed air from a hand pump to pressurize it, not fuel.
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  #5  
Old 11-29-2022, 10:17 AM
Mikeyb Mikeyb is offline
 
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Location: Pasadena ca
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I did leak down pressure testing and bubble testing with air on my -8 plumbing from the from the tank connection fittings to the firewall. It’s probably the best way to find small leaks. I was unaware of the fire danger. Look forward to hearing about that.
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  #6  
Old 11-29-2022, 10:25 AM
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Roadjunkie1 Roadjunkie1 is offline
 
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Location: Erie, Colorado
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Default Fuel line pressure testing........

Quote:
Originally Posted by UNCRV View Post
.........inflated the system to 50 psi. I found several leaks using dish soap and tightened those connections and pumped the system back up. After 24 hours it lost 10 psi. Is this acceptable or do I need to chase this down?
I believe testing hose/line pressure to twice what you expect the system to handle is sufficient. That would be 20 psi for a fuel line as most will only see 10 psi in service.
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  #7  
Old 11-29-2022, 10:26 AM
UNCRV UNCRV is offline
 
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Location: NC
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Default

Quote:
Originally Posted by Mikeyb View Post
I did leak down pressure testing and bubble testing with air on my -8 plumbing from the from the tank outlet fittings to the firewall. Itís probably the best way to find small leaks. I was unaware of the fire danger. Look forward to hearing about that.
Did you have the fuel pumps installed? Thatís the only thing I was curious about potentially damaging.

Was this fire using air or was it using fuel? Iím curious about that as well
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  #8  
Old 11-29-2022, 10:28 AM
Freemasm Freemasm is offline
 
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Yeah, sorry. Tend to scan versus read for detail these days which is not appropriate obviously, Read "pressurize with fuel pumps..." and skipped forward. Known by several names such as "in-service leak testing" in industrial world. My apologies.
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  #9  
Old 11-29-2022, 11:01 AM
Mikeyb Mikeyb is offline
 
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Fuel pump installed. Limited pressure to 30 psi but I have an AFP FI fuel pump. I found a leak in the pump!
Leak testing is an art. It’s hard to define an acceptable leak rate. You are looking for bubbles that take 10 minutes to form 2mm diameter in pure water. Using a real leak detection fluid like “Snoop” helps because it forms small bubbles faster that look like fuzz. It’s not hard to get it tight enough that the pressure remains unchanged for days and you can see the pressure rise and fall with temperature.
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Last edited by Mikeyb : 11-29-2022 at 11:07 AM.
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  #10  
Old 11-29-2022, 02:40 PM
UNCRV UNCRV is offline
 
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Location: NC
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Quote:
Originally Posted by Roadjunkie1 View Post
I believe testing hose/line pressure to twice what you expect the system to handle is sufficient. That would be 20 psi for a fuel line as most will only see 10 psi in service.
I could be mistaken but I think the 12is runs about 45 psi. With 4 lines installed with several fittings And pumped up to 50 psi I had a 2 psi drop over about two months which could have been from temperature drop also. However now I have added about 4 more lines plus multiple other fittings and the pumps and filters so wanted to check all that too.
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