Use of rubber couplings

I am considering the use of a rubber coupling on 2' pvc on the intake side of my pump. Is this advisable?

Don't know what you mean by 'rubber' couplings. I've been using sections of straight auto radiator hose to isolate the pump and filter and they've been in place for maybe 6 years? Not sure. They are on the pressure side too and are holding up just fine. Suction side should be easy. Just be sure the couplings won't collapse under a vacuum and inspect them after a few months to see if the chemicals are attacking the material. The advantages are quieter operation and reduced stress on the pipes and joints as they can move a little.
Al

I believe the rubber couplers that he's talking about are ferncos. I've seen them on some filter installs.....but the pool co. I work for doesn't use them.

I know exactly what he means. Plumbers use them to repair PVC in tough places all the time where there is no "give". Home Depot and Lowes sell them. They are a chunk of black rubber pipe with a hose clamp at either end in a pre-formed groove. They are sized exactly for the PVC you are joining.

I do not know if they are pressure-rated, like Schedule 40 fittings.

That's exactly right. On the intake side, I used a 2" coupling on the pump intake side and a 1.5" coupling with a metal shirt which I would suspect would keep it strong enough to withstand the pressure. I have had the pool open for about a week now and all is well.

I looked at the Fernco website and all their standard couplings seem to be rated at 4.3 psi max and 140 deg F. There may be high pressure couplings but none were obvious and I admit I didn't browse a lot. I've only seen these used on sewer lines. Radiator hose has a reinforcing fabric moulded into the hose and the hose is designed to withstand pressures well over 15 psi, the typical automotive cooling system pressure, and temperatures upwards of 250F plus the harsh underhood environment. The gap in my 1.5" pipes is maybe 4-5" and that leaves plenty of wiggle room.
Al

i am using 2 of these couplings and they came from Lowes - they have 4 clamps and they work great but let me give a word of caution - on the pressure side between the pump and valve mine came apart when i needed to backwash - pressure wasnt terribly high but the pvc pipe slid right out of the couple and if had not been standing outside of the pool house and heard it then it would have drained 40k of pool water into pool house with 220v all over it so make sure you tighten clamps and keep an eye on the rubber to make sure its holding up - from taht point on im cautious about leaving home or coming inside with pump running - i dont usually run the pump unless we are out there unless im going to be back and forth all day - if i had it to do over i would not use the rubber and plan to put a pvc coupling in there - i had to replace the pump because of a inline chlorinator ate everything up because i didnt run it all the time - chlorinator is gone and i went with rubber coupling just because of ease of fixing it - if you can easily use pvc i would just for piece of mind

I have used mission couplings and air tested the lines to 5psi before. Sewer lines, and house services. These were 6" - 12" and when you put air to them, they would blow up like a balloon, but they never failed. Usually we would try to have them buried though when we did it. Sometimes the only way to tell if you solved the leak was to go about it like that.

With that said, you are not really creating any pressure like that are you? It is a suction, and the return should not have much resistance. But, there are couplings called no-shear ones, and they have in addition to the two hose clamps, a stainless steel sleeve around it.

I think it would work, now would I do it, no. I would use a union, whatever the benefit of using a mission coupling would be, it would matched and exceeded by a union.