Cheapo board dryer sucker

I bought a cheapie eBay 12V vac pump..... which I was sure was just an aquarium pump labelled backwards.... for drying out boards. Worth a try at $20...
Pleasantly surprised on first try - I have it sucking thru a watertrap of 1" ally pipe and after 2hrs it was full.

Not even sure the water was getting in near the vent plug, but clearly this does draw down well :)

As to longevity, who knows but they reckon 2hrs on and 30min off for safety - but it is not getting hot. Might need a bigger trap and a timer... :)

Do you need to vent elsewhere on the board to allow for throughflow of air?

Did you suspect your board was sucking water or did u try just in case ?
Could the compressor be producing some of that water ?

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Mastbender said..
If it's pulling water out fairly easily, it does have air flowing thru, and is where the water probably came in from.

Yep, and if you you use a length of plastic pipe as a stethoscope you should be able to find where the air is sucking in.
if there's no sign of dings, then probably a loose foot strap plug, mast track or fin box.

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decrepit said..

Imax1 said..
Could the compressor be producing some of that water ?

No Col, the inlet is from the board, flowing out to the pump, water wouldn't go backwards against the flow.

Sorry , what i meant was , could the compressor be separating water from the air. If i run my shed compressor on a humid day for an hour it would produce a couple cups of water. My factory compressor makes about 10 liters a week. But if it only sucks a very small amount i wouldn't think it was accumulating that much water.

I am about to travel down this path as well.

How do you attach the sucker to the board plug hole - I don't think that is visible in the photo?

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Imax1 said..
Sorry , what i meant was , could the compressor be separating water from the air. If i run my shed compressor on a humid day for an hour it would produce a couple cups of water. My factory compressor makes about 10 liters a week. But if it only sucks a very small amount i wouldn't think it was accumulating that much water.

I know what you meant, and yes it's quite possible, but the water from the pump outlet is going to atmosphere, not the water trap.
The compressor water is produced when the heated, compressed air expands from the outlet and cools down.
The water Mark's getting in the trap, has to be from inside the board.

From my experience pumping down AC systems you cannot turn the pump on and off. The longer it pumps the deeper the vacuum it pulls. I would just let it run.

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Beaglebuddy said..
From my experience pumping down AC systems you cannot turn the pump on and off. The longer it pumps the deeper the vacuum it pulls. I would just let it run.

With a one way valve check valve u can :)
And this is a bit different,we are not trying to achieve a high vac as it may crush the board. It is just giving the water some encouragement to go a certain direction / break the forces of capillary action that is trying to hold it in the styro. Not going to run a $20 plastic vac pump continuously anyway....


Notwal - no need, as this is damaged so its leaking in a couple of places but in a "normal" job I'd insert hose near the most wet area and maybe a little hole elsewhere or allow the vent plug to be the "elsewhere" hole

Very creative! Thanks

I think I'll drill a couple of small 2 - 3 mm holes on both rails - say around a foot fore and aft of the plug - I don't want to crush my board.

I know where the water ingress came from - some moron (me) left the plug unscrewed on a hot day.

I think the board then happily slurped up that apparent kg of water through the open vent plug. There are no dings whatsoever in the board.

The water has been in the board for some time, so will have spread about. Board lady says that after time it can be a long slow process of getting water out, if not impossible. I'll be happy just to get half a kilo out.

I'd put some black plastic over the board turn it so the vent is as low as you can get it, then start sucking or wicking. If water's been in there a long time and spread every where, then a holes at either end would be much better than holes close to the vent. Airflow thru the damp stuff is going to be more effective than just reduced pressure.

Mastbender, I don't thing it's the size of the pump that counts, it's what vacuum it pulls, because if the board is fully sealed any size pump will bring the board down to the pumps best vacuum eventually. That would be a good thing to know before connecting a pump to a sealed board

This is great! I'm going to get one and give it go

Hay Mark don't forget Boyles Law. Pressure vs Temp vs Volume. en.wikipedia.org/wiki/Boyle%27s_law
Whats relevent here is as soon as you reduce the pressure (i.e vacuum) if the temperature is constant than the volume will appear to expand. I use a vac chamber for degassing my silicone moulds and it produces lots of water from the air even on low humidity days. The chamber is about 20L and it would produce about an egg cup of water per degassing. When I pull vacuum (way lower than your small machine admittedly mine is a 3phase Bush industrial vac pump) a cloud of condensation appears than disappears in the chamber as the pressure drops. As soon as you release the vac the water vapour pulled from the air condenses on the sides of the metal drum but not the clear perspex lid. Im sure you are drawing water out of the board but Ill bet your drawing water from the air as well!
Pete.

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Mark _australia said..
Its drying pretty damn quick now.....

Geeze , if u showed me this side of the board i could have told u where the water was getting in