Blowing out lines - Air Compressor

[doggie]

We go 20 to 25 psi. Good luck

[tonyl]

I've always used my shop vac (5hp Craftsman) to suck out the return lines, skimmer, pump basket reservoir, and chlorinator before the SWG. Has worked just fine for my 10 years of IG pool ownership. The only drawback is you have to empty the container, obviously. Just wanted to throw in another option for those that don't wish to buy an expensive air compressor or blower.

Hope this helps, Tony

[haeffnkr]

Mine was set to about 50 while ago in my test.
It appeared to be fine.
Maybe I should back it off.
Tomorrow I plan to close the pool - after I get a few more supplies later today.

Anyone else have an opinion on the best pressure, but not too high?

thanks Kevin

[expose]

Speaking as an engineer, and NOT a pool expert, I say that pressure and volume are often misunderstood.

When attempting to blow dry the inside of a pipe, you need as high of a velocity as possible (essentially a high "volume"). The resulting pressure is a function of the type of pipe, its diameter, it length, and so on. Additionally, if the other end of the pipe is under water, the pressure increases with water depth. In the case of the return lines, I'd say you want as much velocity as possible. The pressure will take care of itself. In other words, you won't be able to over-pressurize the lines regardless of any pressure settings on your compressor. I would think a leaf blower would be more appropriate. Of course if you have some kind of a MONSTER air pump, you could blow your pipes apart. You know, if you take the exhaust from a jet engine and blow it through the lines, you're asking for trouble. But I can't see ANY normal industrial/home air compressor or leaf blower creating that high of a velocity and resulting pressure.

In the case of a main drain, you aren't trying to "blow it dry," so you don't need high velocity (volume). All you need is enough pressure to overcome the pressure at the lowest part of the drain pipe. Normally, that might be about 10 feet below the surface of the water, and that would result in about 5 psi. You could literally pump it out with a bicycle hand pump. As you apply pressure on the pump end of the drain pipe, the water will go deeper into the pipe, until eventually you build up enough pressure to reach the low spot in the drain pipe. At that point, bubbles will begin to emerge from the drain. Any water remaining in the pipe between the pump and the low spot will simply drain to the low spot, so that the pipe will be free of water between the pump and the low spot. (Assuming the pipe was properly installed with a continuous slope down to the low spot.) Shut off the valve, and pressurized air should remain in the line all winter if the pipe and valve don't leak. That may be a "big if," but remember that we're only talking about 5 psi, so it doesn't have to be a fantastic quality valve.

I guess there is one more point to make about the first case of the return lines. If you are blowing them out and the water is below the returns, then simply turn off your air source, and then cap the returns. However, if the returns are below water level, I'm assuming you would have to cap them WHILE the air source is on. If that's the case, then it DOES become important to have a maximum pressure setting. Otherwise, you might blow the lines apart. I don't know what kind of pressure swimming pool lines are good for, but I would think that they'd be good for at least 50 psi. Certainly a lot more than any leaf blower would produce (unless of course it's one of those Tool Time Jet Engine Leaf Blowers.)

Sorry about the long reply.

[CelticDaddio]

Ok.... Maybe I am not thinking this through, but how does one blow out the lines? I can borrow an air compressor, or a shop-vac. Where do I connect the compressor/shop vac? Do I need some sort of adaptor?

Thanks,
Ed

[haeffnkr]

I got my pool closed last weekend. Thanks for everyones help.

I used my air compressor, because the leaf blower would not do anything for my lines (??)
I had the compressor set to 40lbs and used a stand pipe that screws into the bottom of the skimmer "box". On my pool, after you remove the skimmer basket I have threads that 1.5" pipe screws into, in the bottom of the skimmer area, I belive this is a standard setup (???), that pipe stays in the skimmer when the pool is closed so make sure you use a LOT of teflon tape when screwing it in so it will not leak. The stand pipe is long enough to stay above the pool water line but lower than the concrete deck. I dont lower my pool level at all for closing. At the top of the stand pipe is another female pipe fitting so that you can screw in a plug. I took a pvc plug, drilled a hole in it and screwed in a 1/4 air fitting into it, when I am done blowing the lines I take out that plug (got that tip on this board - thanks) and put it a standard pool closing plug (same size as the first plug for 1.5" pipe).
To be double-safe I built 3 other stand pipes with 90s on the end and put them on my return jets, they too are above the water line.
So I put the pump on recirculate and hooked up the air compressor. I blew out the main drain/return air locked them with the valves by the pump. I then blew out each return, with the plugs on 2 of the 3 so full pressure with be going to one return at a time. After a few rounds of this I was done and could not hear any more water gurgling in the return pipes.
I then took the rv-antifreeze and poured some in each return, since my stand pipes were above the water level this was easy. I also poured some in the skimmer line for grins. Then used the empty jug as a gizmo.
Pulled the plugs in my pump, clorinator and filter, threw out my puck clorinator and put on the cover.
I was done! -

I appreciate everyone on this board.
thanks Kevin