Clearing an airlock

[Matty F]

We have a tank supply in a mountain hut. Last time someone left a tap on and drained the tank, there was an airlock in the underground pipe that stopped water coming from the refilled tank. I managed to clear the air out of the pipe by sucking it out with a vacuum cleaner. I had no special equipment so I attached the spout of a large teapot to a tap and sucked through the little hole in the lid. The idea was that any water would remain in the teapot. However some water did get into the vacuum cleaner, which I had to dismantle to dry out. What I want to do now is to make a better device to trap the water and stop it getting into the vacuum cleaner. I thought maybe a couple of bottles with pipes to the bottom of each bottle and sucking out from the top. But plastic bottles will flatten with the suction. Any brilliant ideas? Whatever I make will have to be carried quite a long way! (Tomorrow!)

[dennis]

A wet vac?

A 55 gallon drum between the vac and the pipe to collect the water?

Use water (hose pipe) to flush the air back the other way?

[dom]

Sounds like it might be better to reverse-fill the pipe from the tap.

Large closed plastic container near filled with water, hose through a hole in the top and dipping down to the bottom and closely sealed where it passes through the container.

Connect hose to tap, and pressurise the container through the filling hole, with the vacuum cleaner outlet - or any other convenient method you have to pressurise it.

I'm guessing the drop from tank to tap is fairly small (as airlocks don't readily blow out) - so not a great deal of pressure required to reverse fill.

[Gordon Henderson]

I've had success using something similar to that, but using compressed air from the bottom, waiting until it's gurgling out the far-end, then quickly removing the hose (from a handy SCUBA cylinder) Then, rather than the water trickling down to a closed tap, it has a bit more momentum which carries it all the way to the open tap without any chance to airlock...

It really stirs the tank up though, so any sediment is coming down the pipe and may take a while to settle out...

Gordon

[Tim]

Can you buy one of these locally?

suck as well as blow (air & water) although I can't say whether it would produce enough negative pressure for your purposes.

Tim

[Matty F]

When there is an airlock, we can't get any water from anywhere. The tank is too deep to get water out of it. The suction method works so I'd like to persevere with that. Blowing air doesn't work, we tried it with a high pressure pump. We can't dig up the pipe - it's 80 years old and there are tree roots over it.

[JimK]

have a google on here for "cyclone" and "vaccuum" (sp) - a thread a while back had a link to a webpage on how someone had knocked one up for a workshop vac so that the vac's filters didn;t get bunged up so quickly....

- in your case I would fancy a tall, largeish - 30litre? plastic bucket and lid could be adapted or anything you got around - oil drum?

Holes in the lid for hose from tap (hose down to base of bucket), and vac nozzle just into top maybe at an angle or more elaborately - inverted with pushfit waste pipe fittings?, if smaller bucket add some "baffles" inside to make the path longer for water to resist it being sucked "straight" into vac... etc??

Cheers JimK

[JimK]

or another one that just sprang to mind - depends how much sucking you had to do but;-

feed strong wire/string down a length of hose pipe - tie a small piece of sponge to one end of wire, saturate it, dram into end of hose, connect hose to tap. then from other end draw wire out of hose rapidly to create suction et voila.

Obv depends how far the airlock is away vs agro of feeding wire down hosepipe :>) but if you *had* to do it without power or much kit a variation on the theme may work and could be rigged up in advance of hauling the hose up the mountain....

Cheers JimK

[John Rumm]

Here's one:

D has a few more on his site.

You don't need any cyclone action really - just a dump bin of some form with air drawn out at the top.

(a wet n dry vac would be the obvious solution here!)

[JimK]

ermmm carried up a mountain ? altho fact it has power (I assume from refs to vac earlier) suggests there maybe more obvious solutions....

[Matty F]

Yes a wet vac would be the obvious solution, but I'm not paying for that or carrying it up when there is a perfectly good vacuum cleaner there already. Yes there does happen to be electric power there. The teapot worked rather well and I imagine that two teapots would eliminate all the water. I thought somebody might suggest something better and more ingenious.

[Matty F]

Last time I removed the airlock it required a lot of sucking, say several minutes with a vacuum cleaner. A cyclone system would work fine but I don't have time to make that right now. I do have bits of pipe and duct tape!

[JimK]

did the teapot need periodic emptying during this several minutes? and how big was the teapot? just pondering whether the size of the steam hole (i think) you were sucking from was a bottleneck.....

cheers JimK

[Matty F]

The teapot was about a foot in diameter and the hole was where I removed the knob on the lid. I did have to empty it several times.

[F Murtz]

You can get small pumps that fit on a drill fairly cheap,with which you could reverse prime the system.

[Mark]

I use a camping air bed pump that also deflates (them) to bleed stubborn radiators, i would have thought this would also work for what you need.