Quick Huma Regulator Question

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UCChris

UCChris

Member
Mar 12, 2017
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Chicago, IL, United States
I'm prepping my .25 Flash for a Huma reg that I ordered last night. I'm filing the groove in the threads and am testing the air flow by doing the whole soapy water and blowing through it. My question is how much air does it have to be able to move? Right now I am getting bubbles through the vent hole I grooved into the tube, but I can't feel the air on my bare finger. Should I file the groove in the threads deeper until I can feel a lot of air out of the vent hole?
 
There should be no bubbles or detectable flow out of the vent. Check your O-rings carefully.

To explain what the vent does, it provides an equalization path for infinitesimal migration of air around the O-rings as the piston cycles back and forth (and/or diffusion of gas through the O-rings). O-rings are not totally impervious so if there were no vent, the chamber between the high- and low-pressure sides would slowly become pressurized. We’re talking over a period of days or weeks, not minutes. If that were to happen, the setpoint would shift.

So in your case, it’s doing it’s job but if you’re getting bubbles, there is a seal leaking on one side or the other.
 
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There should be no bubbles or detectable flow out of the vent. Check your O-rings carefully.

To explain what the vent does, it provides an equalization path for infinitesimal migration of air around the O-rings as the piston cycles back and forth (and/or diffusion of gas through the O-rings). O-rings are not totally impervious so if there were no vent, the chamber between the high- and low-pressure sides would slowly become pressurized. We’re talking over a period of days or weeks, not minutes. If that were to happen, the setpoint would shift.

So in your case, it’s doing it’s job but if you’re getting bubbles, there is a seal leaking on one side or the other.
Click to expand...

I think I did a crappy job of explaining myself. I am installing the tube with no o-rings so that I can see that I have made an adequate path for the atmosphere venting. I haven't installed the Huma reg yet. 

Edit: I re-read your post and I think I actually got my answer. The atmosphere venting is just to make sure that the middle chamber between o-rings doesn't get pressurized. So there's no significant volume of air going through the vent, so it really only needs to be a pinhole.
 
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Ah okay, yeah I overlooked the “ordered the reg last night” and jumped straight to what sounded like the symptom of a leaking O-ring.



You picked out the relevant part though. As long as there is some teeny tiny path for air to escape, it will do its job. In most cases the threads will have enough leakage but the practice of plowing a groove makes dead certain of it.
 
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