Hello guys,
do you guys have any suggestion on how to maintain an area to be water/gas proof?
i made a check valve design where rubber meets metal. yet, when being tested in actual condition there is huge leakage in two directions (6 & 12 0'clock).
the flow is from upward.
I think that the preload on the rubber gasket might be unequal and insufficient at 6 and 12 o'clock. Try to increase it. Just my first thoughts.
Hi,
can you show the lid also?
Have you checked the planarity from lid and body?
The direction of the thinner sealing lip looks in wrong side when pressure comes from downside it will be kicked to outside.
I mean, we use check/foot valves a lot in the oil field. but they can be finicky to get a "perfect seal". To keep seal in the negative direction (the top side in this case) it can take 500 psi to actually seat. Some designs use a preloaded spring to hold artificially create that pressure. If it's just the tip leaking (12 o clock), double check that the flapper is landing "flat". You might need to move your hinge out a bit.
Check out the Weatherford Safety Valve, I remember them having a good rep for sealing in the field and having good marketing material to reference.
Overall, I find them to be touch and go in the long run, I would suggest changing to a different valve (spring loaded ball valve) if you have the room to put it in, and don't need the open ID. Something is this family:
https://www.specialtymfg.com/wp-content/uploads/2019/02/check-valve-tutorial.pdf
I agree with some remarks above, but you should also check the grade and type of material you use for the gasket. Some rubbers are not suitable for certain applications. You can only compress rubber so much. If the part you are trying to seal is not strong enough to compress the gasket sufficiently, it will never seal well. Hope it helps
Agreed, the sealing lip is on the wrong side, when pressure is added the lip will just fold over at the weakest point. Flip the direction of the yellow outlined lip so that the lip is pointing up and to the right. ***And create a recess in the metal lid so the lip of the seal is received and forced against it. Is there a clamping force for when the lid is shut? This is not an easy task and will take some fiddling to dial in the parameters...
sorry for my late reply.
i already sliced the body. it shows that there is different thickness of the rubber profile. one is very thin and the other is very thick. i'm assuming that the thick side might cause it not get better sealed because it considered not elastic.
fyi : hardness is 70 Shore A, equals with car tire hardness. material EPDM and NBR rubber.
Dude, no one knows your design better than you...If the thicker profile is at both 6 and 12 o'clock then maybe that's the issue? If its only on one side and it leaks at both positions then its not the thickness...You are going to have to tinker with this problem or re-design both the seal and the lid to receive each other better or to be rounded as to mimic the ball valves in the link:
https://www.specialtymfg.com/wp-content/uploads/2019/02/check-valve-tutorial.pdf
If I were you I would talk to a senior engineer at your company...this is not an easy task.
the leakage occurs in 6 and 12 o'clock with pressure given is 0.02MPa.
i mean, if the rubber already hit/pressed by metal plate from above which might has it's weight to touch the rubber, why still leak?
yes, i already discussed with senior engineer and he only focused with the metal plate flateness and roughness which i already check still ok.
later i will create an animation of how the leakage happens and post it here, so you guys could spot something strange that i didn't catch and hopefully can give an advise.
What you need is a typical submarine hatch seal: a square or rectangular rubber seal of no more than Shore A 20 to ~30 to insure sealing at the pressure you indicated. In this case a pressure of 0.02 MPa (~3 PSIa) is not enough to force a lipped seal against a mating flange, promulgating leaks. A softer seal that extrudes around a radiused ring when seated will seal at much lower pressures, and if the lid has some free movement on its hinge it will conform to the plane of the receiving face, effecting a complete seal not depending on pressure from the gas / liquid to seal. Depending on the size of the lid it may be necessary to provide some sort of latch mechanism or weight to retain contact. Of course the seal can be either in the lid or the body as long as the mating surface is kept clean and polished.
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