So, I have been wanting to dry my board out a wee bit faster using vacuum and I have got hold of this cheap single-stage vacuum pump, which so far I have been reluctant to use as I am a bit nervous about collapsing or delaminating the board (despite having drilled an extra 6mm hole in the bottom from where I am using an aquarium vacuum pump to suck out of; air flows in to the board via the vent hole).

The pump specs say 2Pa (15micron) Partial Pressure and 150micron Total Pressure, which is about 20Pa, the latter which is (apparently) a paltry 0.00019736atm (approx. 1/5000) or 0.003psi (WTF?), but I can feel this much more acutely on my tongue than my aquarium pump. It's not been quite warm enough here yet to really heat up the board consistently over a clear stretch (I am expecting 2 to 4 weeks), which is what I really need, hence the foray into the vacuum (unless that's considered not that useful, or even that "very bad things" could happen ).

Pics of my fish-aquarium vacuum pump are here www.seabreeze.com.au/forums/Windsurfing/General/Sanding-back-extra-coat-of-paint-to-reduce-weight--while-I-wait-for-sun-to-dry-it-out-?page=1, but TBH I am less than impressed by the suction generated, it is pretty minimal, even when I stick it on my tongue. I mean it is working, just with a very, very low suction.

I have read a number of threads on seabreeze about suction pressures including this one, www.seabreeze.com.au/forums/Windsurfing/General/sailing-with-the-plug-out?page=1 (which seemed to end up being a bit of a pissing contest between barn and DrJ) but I remain unclear on what sort of pressures I should limit it to. One other thread says stay above 0.3atm. www.seabreeze.com.au/forums/Windsurfing/General/Getting-water-out-of-board?page=1, this one says 0.5atm. www.seabreeze.com.au/forums/Windsurfing/General/Forgot-to-tighten-the-vent-screw?page=1. Some others have mentioned a duty cycle of 3 to 4 secs on, then 3 mins off. The pump itself says don't run it for too long.

I am about to go buy a vacuum gauge and rig up a bleeder valve to control the suction (if needed), but before I do any of that, I thought I would come see what the collective wisdom on seabreeze about pressures. Thoughts, recommendations?

k.

Mark _australia said..
Those little Chinese copies don't move much air but they will draw down to almost full vac - as they're designed for evacuation of fridge systems - so can definitely implode a board
limit to about 8psi and you should be fine.
With the other hole you might not even be able to achieve that anyway = safe

Cheers thanks Mark, just what I needed to know .

decrepit said..
I have a big pump, as long as I have 2 holes, I just let it rip, pressure doesn't drop much until you seal the 2nd hole. but don't do that.

It's good to have a water-trap inline before the pump intake. most pumps don't like water in them

Cheers and will do on the trap, totally intend to do that.

Thinking a bit of end-capped PVC with in-out hoses and a wee tap at the bottom to check my winnings.

Forgot to warn u most of the oil trap exhausts are crap
vent it to outside, just put the pipe where it doesn't matter

Nup too hard I vented into a bucket of coarse sand and u still get oil vapour wafting out. Not worth it as it will screw up every other job in lamination or painting.
A clear pvc tube is a good fit, run that outside and stick the end in the garden
neighbours garden, even.

mcrt said..
I would not use that pump...
Get an aquarium electric pump, they are real cheap,quiet and made to run 24/7.
Put an entry and exit hole in the board ,plug the pump in and place the board in the warmest room you have.I use the boiler room.
Leave it for days and weigh it to see how it evaporates and pushes the vapor out.

Lol You mean like this one ?
www.seabreeze.com.au/forums/Windsurfing/General/Sanding-back-extra-coat-of-paint-to-reduce-weight--while-I-wait-for-sun-to-dry-it-out-?page=1#7

Tried that one for two weeks but I think the board has been water logged for a very long time and I don't think I have enough warmth from the sun atm.

is there a specific reason you think it's not as good or detrimental?

Mark _australia said..

mcrt said..
I would not use that pump...
Get an aquarium electric pump, they are real cheap,quiet and made to run 24/7.
Put an entry and exit hole in the board ,plug the pump in and place the board in the warmest room you have.I use the boiler room.
Leave it for days and weigh it to see how it evaporates and pushes the vapor out.

Why not? You can build boards with it.
they're designed for continuous use in hvac. fair enough the 5cfm and larger are far more useful but this being only 1.8cfm perhaps lends some aspect of safety to his endeavour


I don't think I've heard of anyone actually drying a board with a tiny pump.

Because they are very noisy, dirty and designed to pull a strong vac which you do not need.
You just need 2 holes, heat + airflow
If the board is very waterlogged gravity will do the heavy lifting.
When it stops coming out plug the pump in to get air circulation going.
My point is that "vacuuming" the board dry will not take out much more water than gravity if any.

Afterwards you can only facilitate the transfer of liquid water between the EPS beads to water vapour and then push that moist air out replaced by warm dry air...again and again.
The more heat (within EPS limits) and airflow the better.But you need both.

If you want to run that pump for days go for it, i just think it is unnecessary wear on the pump plus noise torture.

I'll get probably massively burned for saying this, but I just leave my watery cracked boards in a warm car on a sunny day* in the car park at work, with the windows open a 10cm crack, and check on the board every 30 mins or so. The water bubbles out - in quite a satisfying way - once it stops bubbling I leave it for a few hours more and reckon it's probably fairly bone dry by that point. Job done.

None of my boards have exploded so far, and as far as I know, I haven't died.



*Yes, I know you really aren't 'supposed' to do this and it is a really, really bad thing and baby robins will die.

mcrt said..

Mark _australia said..

mcrt said..
I would not use that pump...
Get an aquarium electric pump, they are real cheap,quiet and made to run 24/7.
Put an entry and exit hole in the board ,plug the pump in and place the board in the warmest room you have.I use the boiler room.
Leave it for days and weigh it to see how it evaporates and pushes the vapor out.

Why not? You can build boards with it.
they're designed for continuous use in hvac. fair enough the 5cfm and larger are far more useful but this being only 1.8cfm perhaps lends some aspect of safety to his endeavour


I don't think I've heard of anyone actually drying a board with a tiny pump.

Because they are very noisy, dirty and designed to pull a strong vac which you do not need.
You just need 2 holes, heat + airflow
If the board is very waterlogged gravity will do the heavy lifting.
When it stops coming out plug the pump in to get air circulation going.
My point is that "vacuuming" the board dry will not take out much more water than gravity if any.

Afterwards you can only facilitate the transfer of liquid water between the EPS beads to water vapour and then push that moist air out replaced by warm dry air...again and again.
The more heat (within EPS limits) and airflow the better.But you need both.

If you want to run that pump for days go for it, i just think it is unnecessary wear on the pump plus noise torture.

He is doing exactly what you do it's just a bigger pump.
it seems most people here give up on aquarium pumps as the move bugger all air. I never had any method work at all, except for a big hole at damage site and time.
when it's had a number of points of ingress and it's spread evenly through the board, nothing works to get the last say 500ml out

Mark _australia said..

mcrt said..

Mark _australia said..

mcrt said..
I would not use that pump...
Get an aquarium electric pump, they are real cheap,quiet and made to run 24/7.
Put an entry and exit hole in the board ,plug the pump in and place the board in the warmest room you have.I use the boiler room.
Leave it for days and weigh it to see how it evaporates and pushes the vapor out.

Why not? You can build boards with it.
they're designed for continuous use in hvac. fair enough the 5cfm and larger are far more useful but this being only 1.8cfm perhaps lends some aspect of safety to his endeavour


I don't think I've heard of anyone actually drying a board with a tiny pump.

Because they are very noisy, dirty and designed to pull a strong vac which you do not need.
You just need 2 holes, heat + airflow
If the board is very waterlogged gravity will do the heavy lifting.
When it stops coming out plug the pump in to get air circulation going.
My point is that "vacuuming" the board dry will not take out much more water than gravity if any.

Afterwards you can only facilitate the transfer of liquid water between the EPS beads to water vapour and then push that moist air out replaced by warm dry air...again and again.
The more heat (within EPS limits) and airflow the better.But you need both.

If you want to run that pump for days go for it, i just think it is unnecessary wear on the pump plus noise torture.

He is doing exactly what you do it's just a bigger pump.
it seems most people here give up on aquarium pumps as the move bugger all air. I never had any method work at all, except for a big hole at damage site and time.
when it's had a number of points of ingress and it's spread evenly through the board, nothing works to get the last say 500ml out

I wear a carbon kneebrace so i ding my boards often, sometimes the dings are tiny, plus the usual plastic insert/carbon joint suckers.
I have dried my boards to the last gram (after 1kg/1 liter ingress once) a few times with a tiny palm sized aquarium pump, a boiler room (around 30? C ) and two 5mm entry and exit holes.One at the tip,one at the tail.And patience, might take a week.

-Drain by gravity
-When little comes out plug the aquarium pump in at high hole.This way condensed water may drip out by gravity too.
-Leave for days.Weigh.
-Patch holes.

People normally do not understand that heat alone will only vaporize the water at the hottest points inside the board but it will not come out by magic unless you force a constant airflow (dry air in,moist air out).
Without airflow the moist air will just condense on a colder area inside the board.
Think of a wet sponge inside an open bottle placed in the sun, it will take ages for it to dry fully.Force (dry) air circulation and things get moving.

Bigger pump will work quicker,sure, but runing an oil lubed vac pump for a couple days would get me evicted from my own home :(

Yes i like the paper towel too. I have a small XPS wall oven to cook, around 45?C, boards when i build them, with a fan bathroom heater. Find it effective to speed the drying foam process with paper towel tech. In general i use the pressurise process first, even if it's dangerous for board integrity, push air slowly to move water out is realy effective before final drying with paper towel in oven. Thanks to all those ultralite single skin wingboard i became an expert of drying eps core LOL.

MobZ said..
I had a session the other day with vent screw loose. Was a slogging session too.
I just got the board, it's heavy but I'm not sure how much that session might have added. So it's good to read the tips for drying it.

-vLSrX5Ew0Evl

y, weighing a new board with straps and recording the weight would be helpful. but it's not too late to get an inexpensive digital 'fish scale' online and keep some record of weight changes going forward. but dont stress if you're not identical to factory specs; it may never have been,...

if you havent had chance to examine waterlogged foam, you might be surprised. lightweight board foam may have the same beady appearance but is Not water resistant like white foam cooler foam. lightweight board foam can absorb water like a sponge - once waterlogged you can push your thumb into it and a puddle forms at the indentation. especially now that you have good reason to expect you have some water in there - become more aware of vent open/close and store it with vent open. also look at every crack critically.

at least Goya brand claims use of closed cell foam core (slightly heavier density than lightweight foam) which should at least reduce water absorbing capability a lot.

fwiw - i expect a small qty of water wicks throughout lightweight board foam and probably results in a very only slightly dampish condition at area of its intrusion and would take quite some time of contact with outside air (especially due to small area of contact with air) to come to equilibrium with the humidity of that outside air (speeded up a small bit by providing aquarium air pump breeze inside the vent hole). even if a small amount of water is pretty much absorbed all throughout the board, i expect it still offers up some changes in vapor pressure due to temperature changes.

www.engineeringtoolbox.com/water-vapor-saturation-pressure-d_599.html

an airtight board should be able to withstand some positive or negative pressure changes,... up to some limit. but how that structural limit compares to practical applications occurring at the beach and storage is beyond my experience.

even though changes in vapor pressure may damage a Sealed board at the beach or hot car, it is those changes that are relied on during 'temperature cycling' a Vented board stored in the garage rafters to push a small bit of humid board air out during the warm days, then draw in relatively-dry winter air during the cool nights. repeat, repeat,..