Nitrogen leak testing
Posted: Wed Aug 02, 2023 12:18 pm
I got a nitrogen regulator and bottle for checking leaks. What pressure should I use? How long to let the system rest with no drop in pressure to call it good?
Automotive Air Conditioning Information Forum
Automotive AC Repair and Discussion topics.
https://www.autoacforum.com/
Nitrogen leak testing
Page 1 of 1
Re: Nitrogen leak testing
Posted: Wed Aug 02, 2023 4:48 pm
I've been told several times and read a few places to go to 150 psi. That is what psi I use. I usually let mine rest 30-60 minutes but I know some people let it sit overnight.
Re: Nitrogen leak testing
Posted: Wed Aug 02, 2023 5:29 pm
That is what I understood as well. Something I read a long time ago, evap cores are designed for burst pressure of 150psi.70monte wrote: Wed Aug 02, 2023 4:48 pm I've been told several times and read a few places to go to 150 psi. That is what psi I use. I usually let mine rest 30-60 minutes but I know some people let it sit overnight.
Re: Nitrogen leak testing
Posted: Thu Aug 03, 2023 6:02 am
I pressurized the system and sprayed down the lines to check for leaks. Found the upper condenser fitting leaking,
I replaced the o-ring and pressurized it again to 175 psi at 7:30 pm yesterday with 76°F. Do I still have a leak or are these readings normal?
9:30 pm 72° 145 psi
11:00 pm 71° 145 psi
7:30 am 67° 140 psi
I can assume the overnight drop of 5 psi is from the drop in temperature. What about the 30 psi drop in the first 2 hours? Is that just the nitrogen migrating throughout the system?
I replaced the o-ring and pressurized it again to 175 psi at 7:30 pm yesterday with 76°F. Do I still have a leak or are these readings normal?
9:30 pm 72° 145 psi
11:00 pm 71° 145 psi
7:30 am 67° 140 psi
I can assume the overnight drop of 5 psi is from the drop in temperature. What about the 30 psi drop in the first 2 hours? Is that just the nitrogen migrating throughout the system?
Re: Nitrogen leak testing
Posted: Thu Aug 03, 2023 9:22 am
Yes, the evap seems to be the weak link as far as pressures go for testing purposes. 150 psi seems to work fine.Tim wrote: Wed Aug 02, 2023 5:29 pmThat is what I understood as well. Something I read a long time ago, evap cores are designed for burst pressure of 150psi.70monte wrote: Wed Aug 02, 2023 4:48 pm I've been told several times and read a few places to go to 150 psi. That is what psi I use. I usually let mine rest 30-60 minutes but I know some people let it sit overnight.
Re: Nitrogen leak testing
Posted: Thu Aug 03, 2023 9:27 am
I would think that you shouldn't have any significant drop if you don't have a leak but since it didn't drop much for about 10 hours, I don't know. The temperature drop is not that much during the 12 hours time period so I wouldn't think it would cause the 35 degree total drop.atikovi wrote: Thu Aug 03, 2023 6:02 am I pressurized the system and sprayed down the lines to check for leaks. Found the upper condenser fitting leaking,
I replaced the o-ring and pressurized it again to 175 psi at 7:30 pm yesterday with 76°F. Do I still have a leak or are these readings normal?
9:30 pm 72° 145 psi
11:00 pm 71° 145 psi
7:30 am 67° 140 psi
I can assume the overnight drop of 5 psi is from the drop in temperature. What about the 30 psi drop in the first 2 hours? Is that just the nitrogen migrating throughout the system?
Re: Nitrogen leak testing
Posted: Thu Aug 03, 2023 11:08 am
Well, at 10 am it was still at 140 so I vacuumed 2 hours and then charged. Will see how long it lasts.
Re: Nitrogen leak testing
Posted: Fri Aug 04, 2023 7:55 am
I think you made the logical choice.atikovi wrote: Thu Aug 03, 2023 11:08 am Well, at 10 am it was still at 140 so I vacuumed 2 hours and then charged. Will see how long it lasts.
For that area, you can test for leaks with soap bubbles.
Re: Nitrogen leak testing
Posted: Sun Aug 06, 2023 11:56 am
A 5 psi drop at rest wouldn't be a way to measure if you lost some refrigerant. I would attribute that to a temperature change.
The soapy water test is a better way to test than with dye. I prefer an electronic leak detector but would be fine with soapy water in lieu of.
Nice job diagnosing.
The soapy water test is a better way to test than with dye. I prefer an electronic leak detector but would be fine with soapy water in lieu of.
Nice job diagnosing.
Re: Nitrogen leak testing
Posted: Sun Aug 06, 2023 6:18 pm
Here's a nitrogen pressure calculator. I have found that it follows what Fieldpiece uses for their temperature compensation in their gauges for their "tightness test."
https://www.oceanhvac.com/nitro.php
https://www.oceanhvac.com/nitro.php