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Leak test correlation - Bubble to Air

triathlonx13

Starting to get Involved
#1
I'm working to establish a pressure decay maximum psi loss. Is there a standard to reference or a correlation study of sorts that can be referenced.

For instance: Using a typical pressure decay unit with parameters of fill time, stabilization time, tes time and pressure. And ultimately the psi decay input decay.

Test Method Validation - How did you determine the air decay over what amount of time to demonstrate a No-Fluid Leak.

Can the allowable psi decay be 0.16 at 30 seconds? How did you choose the 0.16 psi ??
 
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optomist1

A Sea of Statistics
Trusted
#2
Can you provide a little more insight, what type of leak check are you employing? Reading off a pressure gage? What is the test set up like? What do the design/process/acceptance documents state re: acceptance criteria - leak? What type of device are you testing...you state in the title "Bubble to Air", this would seem to indicate a submerged device...water tank? Are you looking for bubbles as an indication of pass/fail?
 

triathlonx13

Starting to get Involved
#4
Can you provide a little more insight, what type of leak check are you employing? Reading off a pressure gage? What is the test set up like? What do the design/process/acceptance documents state re: acceptance criteria - leak? What type of device are you testing...you state in the title "Bubble to Air", this would seem to indicate a submerged device...water tank? Are you looking for bubbles as an indication of pass/fail?
Using a TMESOLUTIONS Pressure decay unit. (Like a Sprint and USON).

Medical Device must not leak fluid at 30 psi.

When I refer to Bubble.... Basically referring to charge device with air and submerge into water bath and look for bubbles (leak).
 

triathlonx13

Starting to get Involved
#5
We used no bubbles for 15 seconds at 15psi for in process auditing of automotive vacuum lines. I think it was 3 samples per shift.
Yes the Bubble leak test is something we can do for development - but in production we can't do water submerge and needs to be leak tested 100% non-destructive.

Looking to understand how to correlate bubble form to decay limit. Like if I set the decay limit to be .16 psi in 30 seconds.... how is the .16 psi decay chosen?

How are these pressure decay testing units validated (TMV) from fluid leak to air leak, etc?
 

Johnnymo62

Haste Makes Waste
#6
Our customer (Ford) always specified the maximum leak value (0.5SCCM). That's where I would start. The customer may specify the test profile also.

Then you would need to develop a leak test profile of fill, stabilization and test time that would meet your quoted capacity. Sometimes we had to use two testers to meet capacity requirements.
 

optomist1

A Sea of Statistics
Trusted
#7
My experience is in Aero/Automotive....whenever we performed leak checks.....always used a Helium sniffer, or similar device that produced (assuming an MSA performed and the Customer design Agency/Authority agreed to accept reject criteria.) reliable results. The agreed to test procedure/setup/equipment must be vetted for repeatability/reproducibility...MSA

RE: how is the .16 decay chosen? Did your customer provide this criteria? Hope this helps.....
 

Johnnymo62

Haste Makes Waste
#8
I would ask the tester manufacturer's recommendation of a profile for the psi and volume drawn.

It's kind of dumb that a time isn't specified because everything leaks eventually.
 

triathlonx13

Starting to get Involved
#9
RE: how is the .16 decay chosen? Did your customer provide this criteria? Hope this helps.....
0.16 decay was what they used before..... but my question is how was that pressure loss chosen? See.. I do not see how this test has been supported by a Test Method Validation. As part of an output of the TMV... The decay, in this case 0.16, would be determined/chosen based of the validation results.
 
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