can't isolate a valve!

hi guys,i've got a problem with a paddling pool, and i was wondering if anyone had any better ideas than stripping the pipework/putting in a new valve.basically, the pool has a massive surface area:volume ratio, and the filter screens provided by the pool's owners are inadequate - it looks like there is now a pair of shorts wrapped round the inside of the valve between the balance tank and the strainer basket. The order of the plant goes pool -> balance tank -> pipe splits in two -> pair of isolation vavles (one of which now can't be isolated) -> pair of strainers -> pipe rejoins itself -> pumps -> filters -> pool. This means that it's impossible to isolate the valve, making cleaning the strainers nigh on impossible, and I can't for the life of me get the shorts out. Obviously as it's summer time, the municipality is very reluctant to drain the pool, but that's the only thing that i can think of that will stop the water pressure from a) making it difficult to remove the shorts, b) flooding the plant room, c) drenching me! any thoughts?

Replies

Scott Heusser August 1, 2009 at 8:16am

I've used mats over drain fittings to stem the flow of water. No diving, no grate removal, just a large piece of old autocover fabric placed on the bottom with your t-pole. Tie a rope to the fabric so when you are done you pull it out of the pool.Test ball will work though.
Bruce Hudson July 30, 2009 at 1:49pm

Hey Andrew,

We're rootin' for you! Please let us know how it all worked out.
Rick Larson July 30, 2009 at 9:09am

If this is a standard balance/surge tank then one valve should come directly from the main drain and one from inside the tank. I guess you must have looked inside the tank and sometimes there are isolation valves in there. If not you can turn off any autofill and simply drain enough water from the pool to stop the overflow into the surge tank. That will drop the level in the tank to a level you can work with. I have isolated the main drain line with a large enough rubber mat(s) over top of the grate(s) in the pool.. There should be a pump or filter outlet valve to isolate the return side. Of course the pumps need to be off and people out of the pool. A 4" valve should only have 4 bolts and only take a few minutes of downtime to pull and clean or replace. I have done 10"-12" valves this same way.

Maybe something like this can work?
Todd Rafkin July 28, 2009 at 6:55pm

i WAS GOING TO RECOMEND THE A TEST BALL, THAT IS THE ONLY THING I CAN THINK OF SHORT OF DRAINING.
Andrew Latham July 28, 2009 at 7:55am

cool, thanks! shall give it a go...
Bruce Hudson July 28, 2009 at 7:03am

If the tank is big enough for a swimmer, my suggestion is to plug that sucker and become the hero. It may require scuba or a dive compressor to work effectively and comfortably. to pump up a test ball that deep is no big deal with a compressor dialed down to the appropriate PSI for the size of test ball you're using. Say 40 PSI at the hose? If you don't dive, local dive shops usually can provide the service.
Andrew Latham July 28, 2009 at 6:24am

hi bruce, thanks for the thoughts.

i was trying to work out how to plug the inlets from the balance tank to the pool, i think that might be the only bet - but one that won't be easy! you're quite right, the pumps and valves are a way below the level of the pool water, and about level with the bottom of the balance tank, which in turn is about 8-10 feet deep, and there's not an easy way to isolate/drain the balance tank. so there's always gravity pushing water through the system as far as the pumps. how awkward!

the pipework must be 4" diameter (i think this is part of the problem - the plant wasn't well designed, particularly given the area of the water), so not quite wide enough to easily fit a hand into (particularly when there's water coming against you), or for blockages to easily circumvent the line of the valve and feed into the tank. i think the council might have to bite the bullet and pay for an engineer!

Bruce Hudson said:
Just guessing here that the pumps/ valves are in a "vault" below the tank?
What dia. pipe feeds the valve?
How deep is the tank and can you access the pick-up.
Pneumatic test ball may be usefull to plug the pipe opening so the valve can be serviced.
Bruce Hudson July 28, 2009 at 5:26am

Just guessing here that the pumps/ valves are in a "vault" below the tank?
What dia. pipe feeds the valve?
How deep is the tank and can you access the pick-up.
Pneumatic test ball may be usefull to plug the pipe opening so the valve can be serviced.