Northwest Dive Club

I need to blow out an underground water line for the winter. The line has 3 faucets on it--one faucet is the input and I use one of the other two faucets as as the output.

I thought that using a scuba cylinder would be a good way to go, since I don't own a compressor for air tools. But, I don't have whatever adapters are needed to make the connection between the LP hose and the faucet.

It looks like a key part is a BC inflator post to 1/4" male NPT adapter, like the top item on this page:

http://www.divegearexpress.com/regulato ... _npt.shtml

Now, it is easy enough to order from DGE, but it is NOT easy to buy that $2 part without throwing in another $100 of stuff to justify the shipping costs. If anyone happens to have seen this thing around locally, please let me know.

Or, if there is another way to connect a garden hose faucet to a LP inflator hose, that's good to hear too!

Try UWS seattle or Discount Divers Supply . John at DDS has a big box of random adaptors and stuff to dig through but you might get lucky.

Have an old BC power inflator around?

Get a garden hose thread (3/4") to hose barb fitting at home depot or wherever.
Get a short piece (1' or less) of PVC hose from the same.
Connect threaded garden hose to PVC hose, then PVC hose to power inflator.

Bring the power inflator with you so you can get the right size connectors and hose.

Hook up scuba tank and blow.

PS you could also just buy a new power inflator and replace the one you have (they do wear out anyway). They use your old one as your water line blower.

You don't want to use above 60psi on water lines, Usually use around 45psi.

Jeff Pack wrote:You don't want to use above 60psi on water lines, Usually use around 45psi.

It won't get above 60psi if the valves are open on the downstream ends.

CaptnJack, that's a pretty good idea, thanks. I just replaced all my inflators but I did keep one of the old ones around as a spare since it still looked serviceable.

My water line is PVC and rated for 200 PSI but it uses barbed brass couplers in a few places, and I don't know what pressure those joints can handle. Seems like as long as I keep the faucets open it should be OK, but I'm no buried water line scientist.

The line is 24" underground and hopefully won't freeze anyway, but... better safe than sorry.

24in is below the freeze line. Most residential is 18in or so. Shut off water, open the faucets, wrap whats above ground, and dont worry about it.

The brass will take way more than the PVC. Capt'n Jack's idea is good, but you can do something similar with a "blow gun" attached to a BC hose. Most LDS's have them, used for filling lift bags, or by evil instructors to simulate failures. (glancing at Bdub....)

Do you have convenient access to a tap and die set? I've run a 3/8"NC (I think, feel free to correct me) tap trough 1/4"NPT plumbing fittings to connect the coupler from an old infiltrator to other things for moderate/low pressure convenience uses. You'd probably have to stack a few fittings to get from 1/4" to a useful size unless you just drill and tap a hole in a cap in a more useful size. I'm pretty sure that this is how I've hooked up my regs to my I.P. gauge, don't know what I'll wind up doing when I have to switch to IPv6 though.

You could also consider using a friction fit into a drilled rubber plug from a hardware or homebrew store and avoid all the work if you are willing to deal with a press fit.

JB weld will connect 2 fittings (air tight too) of completely different threadings as long as one fits inside the other. Just sayin'...

JB Weld is part of any good (or bad) toolbox!

You could blow this out orally enough to ensure no problems. Water freeing in pipes will do no harm as long as there is room for the expansion. Problems usually happen when it freezes in two places and then as the middle freezes and expands it has to break something. If you have a simple straight pipe coming out of the ground, it will begin to freeze at the place most exposed to the cold, which usually would be the valve, as it has the most surface area. No problem if it the expansion can be taken up by the underground pvc filled with liquid water. If you have a fitting between the valve and the ground, it will probably freeze that and then water freezing between the valve and the fitting will likely break something.

Just open two of the faucets at a time, and get rid of the water above ground if you want to be sure.

The system is about 250 ft of PVC with standpipes and faucets on each end and the middle. There is one low spot in the underground run where it's likely that water has completely filled the line, with no overhead air gap--but, it will still have expansion room on each end. The system can be left open to the air at 3 points, too

There's no water in the standpipes or valves, nor are there sprinkler heads to worry about... just whatever remains underground.

Sounds like you guys aren't worried about a freeze, especially at 24" deep. My contractor was, though he's extremely conservative. Perhaps it isn't an issue.

At most our ground freezes 6" deep. And that takes a prolonged cold snap (3+ days) of <32F temps all day & night. If you want a forever solution, you could install a vault at the lowest point so you have pipe access there. Then put in a drain at the point. This is how I drain my outdoor water system every October.

I definitely wouldn't worry about pvc buried 24 inches. I have about 1400 feet of it buried 18 inches. I installed yard hydrants, which drain themselves when you turn them off, and that is all I do. Never had any problem, the buried pipe does not freeze. We used to have animals, so every three or four days, I would fill the stock tanks. Water flowed.

When the weather is nicer, you might consider thesehttp://www.amazon.com/Watersource-Frost ... B0009XB4VM yard hydrants, they aren't very expensive.

That is good to hear, thanks!