Suction side air leak

[nthole]

I've got a wicked air leak somewhere on startup this year. I'm running to get a replacement strainer pot oRing today for the pump (Pentair Whisperflow). I opened the suction ball valves (2 1 skimmer 1 pool bottom) and one of the valves is completely missing the ball seat and oRing. I had the pump replaced about 3 years ago before I decided to take on being my own pool man and I'm betting they just tightened the joint up with some wrench instead of replacing the parts they lost and I never knew better. I undid the unions last year in order to more easily fill the pipe running to the bottom of the pool with antifreeze when closing. I'm betting I didn't jack it down like they did so now I have an air leak.

So my question is, I found the mfr of the valve and they have rebuild kits for the valves (seats and o rings). But they sell 3 different version and I don't know which type of oRing I need. It looks like it is related to the TYPE of material the oRing is made of.

http://www.barrettsupply.com/barrett/sp ... kits.htm#3

Those are the rebuild kits but I don't know if I need BUNA-N, EPDM or VITON/FKM oRings.

Does anyone know what should be used in a pool valve? Or does it not matter?

 

[jblizzle]

Here is a comparison of the different types of rubbers:
http://www.jjshort.com/Rubber-Properties.php

I think I would go EPDM based on that info.

 

[nthole]

I first took an o ring off a return valve and put it into the suction valve and viola... air leak repaired. So I guess I have an extra pot lid oRing! I opened it all back up and relubed it just for good measure.

Now I need to get a replacement for the return though as it's got a small drip since there's no oRing. I'm ok with that for now. Better than a pump 1/4 full of air!

I still hear what sounds like some air in the head. Does that seem like just normal water movement? I bled out the air in the system, so maybe that's just the water pressure.

Thanks for the help on which material to pick.