Blowing out the lines

[bigjt_2]

Been researching blowing out my lines and came up with a couple questions listed below. For those interested, here's the background:

So in this video,
https://www.youtube.com/watch?v=_OL4ACvT_QE
the guy suggests using a tankless air compressor, warning that using one with a tank gets an "sudden blast of air" when opening the tank that I guess could damage the pipes somehow. But he doesn't really explain what to do about that burst of air, if anything. He just says "be careful." :-/ And most the people here on the forum seem to be using tank air compressors with no problem.

Also been looking at some threads on this forum like:
What Kind/Size compressor do I need to close the pool?
Lots of really helpful info there on the type of compressor I need, which I appreciate as I had no idea. But a lot of people warn about over-pressurizing the lines.

So my questions are:
1. Is there a danger to my pipes by using a tank air compressor and getting the "sudden blast of air" the video warned about? If so, what do people do to alleviate that?
2. How do you folks who close your own pools know when the lines are pressurized properly and not over-pressurized? Do you have some kind of tool you use to gauge that?

As always, any help is greatly appreciated.

PS-
Thinking about purchasing something like this:
Hitachi 6-Gallon Portable Electric Pancake Air Compressor (1 Tool Included) [KNT50AB] - $50.00 : Timeubuy.com, One Stop Solution!

 

[pookiesunshine]

my lines are never "over pressurized. i blow from the pump. the return lines are capped while blowing, then any back pressure is relieved when the blower is removed. for the bottom main drain, my shut off valve near the pump is closed while still blowing, so the back pressure is from the water only.

 

[awtrizzle]

Me personally, I use my shop vac in reverse. I shut the suction valve at the pump, plug up my other skimmer suction inside the skimmer (I use a test plug I got at Lowes or Home Depot). Then I blow air into the other skimmer suction until water no longer comes out of the returns.

 

[Demegrad9]

Because this is something I'm starting to wonder about quite a bit as this is my first season closing my pool I can't really answer your questions.

But, for #1. Virtually all these tank air compressors come with a pressure regulator to set how much pressure the tool sees, usually with a max around 90 psi. The 150psi advertised for that pancake air compressor unit you mention is the maximum tank pressure, the tank pressure is higher so it can 'store' some high pressure air while you use the tool so the pump doesn't have to run continuously. Anyway, I'm getting off track, you can just use that pressure regulator to dial down the pressure to almost nothing, hook up the line then start to increase pressure until you see water moving.

 

[AftonJeeper]

Demegrad9 is correct you are looking for air flow not pressure in the lines. I haven't closed my pool my self yet but have done my sprinklers, and if I left my compressor at the usual 80 psi I would blow all the sprinkler heads off my lines. 40 psi is the most you should run and I work my way up there from 20 psi.

A shop vac or dedicated blower fan would be better for most people as a high CFM air compressor isn't something most people need or have around.

 

[bigjt_2]

Thanks for the suggestions everyone. I definitely feel a bit more confident now. Best of luck to you other folks closing your own pools, too.

 

[bigjt_2]

I closed down my pool yesterday. Blew out the lines and sealed them up. Tonight I decided to add some anti-freeze to the skimmer line as extra insurance. Both of my returns are plugged still, I just took out my gizmo from the skimmer and started adding the anti-freeze. I was expecting it to take at least a half gallon and it only took about 1/4 gallon before showing as full at the bottom of the skimmer. Is it possible I have a big air pocket in the line that's not allowing the line to fill all the way with anti-freeze? If so, is that a problem and what are suggestions?

 

[blakeusa]

2" inch Schedule 40 PVC Pipe can handle up to 220 PSI before cracking so I would not worry about using your compressor.

 

[bigjt_2]

2" inch Schedule 40 PVC Pipe can handle up to 220 PSI before cracking so I would not worry about using your compressor.

Thanks for answering the question about using the compressor. Any insight on whether or not I should be worried that it only took 1/4 gallon do antifreeze instead of 1/2 to full gallon? I also opened up my valve that seals off the skimmer/returns to let out air pressure and take the antifreeze in further. It really didn't take much more, though. So now I know I've probably let out some air pressure. I'm pretty sure there's still some water in the lines because I can hear it sloshing about in the tubes. Is there always going to be a small amount of water left over?

 

[AftonJeeper]

While the pipe may be rated for 220 psi any idea what the filter or heat exchanger is rated for?. You need air volume to clear the lines not pressure. I've seen guy who don't know what they are doing shoot sprinkler heads 50+ feet in the air, that was at 80 psi.
Clearing a 2" pipe with a compressor is not an easy task. I have several air compressors, the biggest is capable of delivering 7.7 cfm of at 40 psi each and it takes more than 5 minutes to clear a 1" sprinkler line. I won't even try it them on my pool even though I know others can do it.

As for the 1/4 gallon of antifreeze, seems like a 10 foot piece of 2" pipe could easily hold more than 1/4 gallon. But I have no idea how much should be used in a "typical" pipe.