Testing Hard Fuel Lines for Leaks?

[cv2065]

Hey guys. My 3/8” Nicopp fuel lines are complete with bends and Ham-Let compression fittings. I just need to install in the car. Man those fittings are high end and worth every penny!

Before I install, I thought that I would test the integrity of the fittings...and even more so, my work getting them installed. I was thinking of using maybe a bicycle pump on one end and some soap and water on the fittings to pressurize the line. Anyone done this or have a better suggestion?

Would give some quick peace of mind as I go to install.

Thanks!

96840

[Boydster]

Since my fuel system is running at about 55psi, I set my compressor at 100 psi then used adapters and fittings to install the various lines straight to the compressor. Some I did on the car. The poured a soap solution over the hoses and fittings to watch for leaks.

Its good standard practice to go about 100% over the pressure you'll be putting into it.

Good to see you getting along...

[phileas_fogg]

I tested my lines with a set of fittings (https://www.amazon.com/gp/product/B009S5ICJY/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1), a bicycle pump, & a bucket of soapy water. I know you said hard lines, but when you get to soft lines test them as well and be sure to flex the hose at the fitting. I had a couple of hoses that didn't leak until I started moving the hose around.


John

[cv2065]

I tested my lines with a set of fittings (https://www.amazon.com/gp/product/B009S5ICJY/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1), a bicycle pump, & a bucket of soapy water. I know you said hard lines, but when you get to soft lines test them as well and be sure to flex the hose at the fitting. I had a couple of hoses that didn't leak until I started moving the hose around.


John

Ah, that’s perfect! I can just hook up my soft lines on the end of the hard and test all together. Thanks John!

[mikeinatlanta]

I test my lines with CO2 at around 800 psi. Wouldn't consider less.

[cv2065]

I test my lines with CO2 at around 800 psi. Wouldn't consider less.

How do you go about pressurizing with CO2 at that rate Mike?

[JimLev]

How do you go about pressurizing with CO2 at that rate Mike?

You'll need a tank of CO2 with the appropiate fittings.
Maybe you can get a paint ball tank, they use CO2. Shouldn't be that expensive.

[BadAsp427]

Or you can put it all together and put some good heavy foot pressure on the pedal after they are bleed properly and know that you have a leak or not... ask me how I know....

[Railroad]

I just used the key on method. I did leave a couple of fittings loose. It's not fun watching $10/gallon fuel pump out.

[mikeinatlanta]

It's mind blowing to me that someone could spend this much time and money building a car and then risk it all by not testing lines, but that's just me.

I use a CO2 tank two valves, and AN fittings. Everything on my car is AN. This isn't really the safest way to do it though but can be reasonably safe if you do it right. If a 1/2" line at 800 psi pops a fitting it will make about 150lb of thrust (or more is liquid CO2) so make sure you are careful and never just dump tank pressure into the line. The first valve is opened and that pressurizes the space between the two valves. I then close the first valve and open the second valve. That volume of CO2 will now equalize with the line. I repeat the process until I get full pressure on the line. Should a fitting pop it will only dump pressue in the line rather than full tank force. Still safer than burning down a car and shop though.

[cv2065]

Might stick with the fittings, bicycle pump and soapy water.

John - What pressure did you test at with the bicycle pump?

[karlos]

800 psi? Really? Assuming an operating pressure of 55 psi, an 800 psi proof test represents a proof factor of 14.5. The proof factor specified by NASA for fittings/lines used in human rated spacecraft is only 1.5. The burst factor (point at which the fitting/line physically ruptures) is only 4.0.

A test using a bicycle pump to 100 psi or so is perfectly adequate. Not trying to be argumentative, but 800 psi is extreme overkill.

-Karl

[Dave Howard]

It's mind blowing to me that someone could spend this much time and money building a car and then risk it all by not testing lines, but that's just me.

I use a CO2 tank two valves, and AN fittings. Everything on my car is AN. This isn't really the safest way to do it though but can be reasonably safe if you do it right. If a 1/2" line at 800 psi pops a fitting it will make about 150lb of thrust (or more is liquid CO2) so make sure you are careful and never just dump tank pressure into the line. The first valve is opened and that pressurizes the space between the two valves. I then close the first valve and open the second valve. That volume of CO2 will now equalize with the line. I repeat the process until I get full pressure on the line. Should a fitting pop it will only dump pressue in the line rather than full tank force. Still safer than burning down a car and shop though.


Once the fuel line is tested, you need to connect it to the fuel pump and fuel rail. How do you leak check those connections?

Like some others, I relied on the engineering that went into the components I used. Relied on the safety policies and the procedures, the ISO certification of the companies I purchased from, and lastly, I relied on my ability to read instructions (not watch YouTube) and assemble a fuel system I had total confidence in when I simple turned the key. 800 psi is a little extreme. Whatcha running there, a gas turbine?

[cv2065]

I’m more concerned with the compression fittings. If it was all AN connectors, I might not bother.

[mikeinatlanta]

I'm not leak checking a connection, I'm leak checking a hand fabricated nicopp tube and flare that should have no trouble taking 3,000 psi. Go ahead and ridicule, don't mind me when I laugh when yours burns.

If funny how around here guys constantly offer compliments and kind words of encouragement when someone is building an absolute ****box, but ridicule when someone's quality is what they deem too high.

For those few who actually care: A 1.5 factor burst test is for the rated pressure of the tube, not necessarily the pressure it will endure in use. Also, when talking fittings such as AN on hose, the connection of the hose to the hard fitting is not AN, so you cannot trust AN pressure ratings on any hose end, You must use the pressure rating of the hose and fitting manufacturer.

[edwardb]

Go ahead and ridicule, don't mind me when I laugh when yours burns...

If funny how around here guys constantly offer compliments and kind words of encouragement when someone is building an absolute ****box, but ridicule when someone's quality is what they deem too high.

Seriously dude... Maybe just back away from the keyboard next time.

[phileas_fogg]

Might stick with the fittings, bicycle pump and soapy water.

John - What pressure did you test at with the bicycle pump?

Just like Karlos guessed, 100 psi. According to Dorman tech support, the rubber 800-074 fuel line F5 provides in the kit is tested to 90 psi in the factory.


John

[cv2065]

Just like Karlos guessed, 100 psi. According to Dorman tech support, the rubber 800-074 fuel line F5 provides in the kit is tested to 90 psi in the factory.


John

Thanks again for the suggestion John. I received my pressure test fittings last night and hooked em all up. Tested both the in and out lines up to 80-85lbs, as that is all my pump would handle, but given that the Aeromotive 340 is rated at 40psi, it should be plenty solid of a test. Thanks again.

[Fixit]

We're building street automobiles, not LeMans 24 hour cars, aircraft or the next deep space probe.
Use common sense, historically proven materials & methods, and if you're unsure about your work, ask for help and get someone over to check it.

Brake/Hydraulic lines will reveal a leak almost instantly... and if you're foolish enough to go for a drive without pressing the pedal before leaving you'll be on the Darwin Awards.
Fuel lines tested at 2:1 will be fine. Again, you'll know instantly if there's a leak - shut the damn thing off and fix the problem.


If funny how around here guys constantly offer compliments and kind words of encouragement when someone is building an absolute ****box, but ridicule when someone's quality is what they deem too high.

The compliments & encouragement are for the builders who are "noobs" to building, fabricating, and (sometimes) are embarking on their 1st automotive/mechanical endeavor. Building one of these cars is a daunting project - and they are looking for confirmation and reassurance of what they've done is OK.
Calling someone's hard work "an absolute sh*tbox" is out of line. It may not be up to your standards, but it's not up to you to judge.

The ONLY time harsh criticism is mandated is when something is very wrong and poses a danger to life & limb... but this criticism can be done diplomatically, by offering reasons and suggestions on how to correct it.

[CraigS]

We're building street automobiles, not LeMans 24 hour cars, aircraft or the next deep space probe.
Use common sense, historically proven materials & methods, and if you're unsure about your work, ask for help and get someone over to check it.

Brake/Hydraulic lines will reveal a leak almost instantly... and if you're foolish enough to go for a drive without pressing the pedal before leaving you'll be on the Darwin Awards.
Fuel lines tested at 2:1 will be fine. Again, you'll know instantly if there's a leak - shut the damn thing off and fix the problem.



The compliments & encouragement are for the builders who are "noobs" to building, fabricating, and (sometimes) are embarking on their 1st automotive/mechanical endeavor. Building one of these cars is a daunting project - and they are looking for confirmation and reassurance of what they've done is OK.
Calling someone's hard work "an absolute sh*tbox" is out of line. It may not be up to your standards, but it's not up to you to judge.

The ONLY time harsh criticism is mandated is when something is very wrong and poses a danger to life & limb... but this criticism can be done diplomatically, by offering reasons and suggestions on how to correct it.

Well said.

[cgundermann]

There is a lot of diverse talent on the Forum: young, old, highly educated engineers, folks with many build threads or those with formal automotive mechanical experience. The Forum exists for the joy of the hobby. Several ways to skin a cat...

We are all passionate about OUR builds and the methods we employ. Easy to get our “feel goods” hurt when it is perceived that we are challenged. A good chunk of us are extremely anal perfectionist. I make no apologies for my own obsession in over-engineering things, but - the Forum always offers a good gut check for those of us with that sickness.

I hope that anyone spun-up about this thread, regroups and puts it back in the appropriate context. It is really so easy to take offense in written communication, then a good old fashioned verbal debate. When I was in the Corps, you went behind the barracks and worked it out and then went and tossed down beers with your beaten up brother. Hell, we as group can passionately debate manual versus power brakes & steering to the end of time.

I read the Forum several times a day and appreciate the names/contributors of everyone in this thread.

Chris