Water Table

[Big John T]

How does a water table pump the water up? Is it a bladder in the tank or something like that?

Thanks
John

[millman52]

Although most call them a "bladder tank" They really are not. They are merely a tank large enough to hold 10-15 gallon more water than your tray will need to be concidered full.

Most setups use fairly large inlet/drain back in the bottom of the tray so filling & then draining of the water is fairly rapid.

A valving of some sort, you choose whether simple ball or solenoid valve(s) operated from Mach, is arranged to apply air pressure ( usually not very high pressure) to your "bladder" & force the water up into your tray. When finished cutting release air & allow water to gravity drain back into the tank.

If this isn't enough information let me know & I'll hand draw you a rough sketch of my idea(s) for a water tray & post it up in the next couple days.

99% of what I cut is Ox/Fuel & heavier materials as I stated above. Below is a pic of the small drops & swarf of about 1 1/2 weeks of cutting. I really wouldn't want to have the job of cleaning all this muck from a water table.

My slats are a mere 3" on centers. & still loads of slugs & all the "blow" end up here.

Oxy/Fuel doesn't create near the smoke/fumes as plasma however. My shop is well vented so fumes from the Oxy isn't bad at all.

The pic really doesn't show the volume of crap in the catch trays. That muck is around 3" deep right now. I lift the 2 trays out with my fork lift & dump them in the scrap hopper as needed.

[Big John T]

Thanks for the reply millman52. The attached cutaway view is how I understand that the water table works. Having more water than needed prevents geyser like action as you fill I suspect... And your correct the plasma is a dirty thing and the water table seems to help about 1000% during my tests with an old wash pan...

Thanks
John

[millman52]

Yep that's the general idea. I'd think a sump right around your stand pipe, with the pipe still coming to very near the same height as the bottom of your tray to help keep fines from draining to your tank might be of benefit.

Also you will probably want to use a round tank for your reservoir as air pressure on the flat sides of a square tank will eventually cause fatigue & possible fracture near the welds.

You're exactly correct in the reason for a surplus of water. Even 5# of air pressure would spew water everywhere if a slug of air were to get access to the fill tube.

Of course the larger the transfer tube the quicker fill/drain action you will get. Therefore the less tempting to up the air pressure for quick fill.

Others who actually have these systems would be better to advise you there. I am merely drawing on past experience with similar projects.

[Big John T]

Thanks

John

[Fiero Addiction]

I fill mine with shop air pressure (90psi) through a 1/2" ball valve, I can open it about half way and move 60 gallons into the tray through a 2" pipe in about 45 seconds. I have a flat cap over the top of the pipe to deflect the water, like a cap on a stove pipe. Without the cap the water would hit the ceiling. My air bleed-off is through a 1" ball valve and it takes about a minute to drain.

[Big John T]

Fiero, Thanks for the additional information. That makes sense to have the cap over the top to direct the flow sideways...

Thanks
John

[PlasmaGuy]

John,

Here is a link to my table filling up.

YouTube - Water table Filling up

YouTube - Water table Filling up

'Best money I ever spent.

Luck,

Tom

[Big John T]

Thanks Tom,

Now I just need to devise a plan for my table. I'm using a dog water dish at the moment
it is ok for small parts LOL but the difference is amazing.

Do you cut underwater?

John

[PlasmaGuy]

I have cut under water but now i fill the tank until the water is touching the underside of the plate. I have cut successfully with my 1650 under water w/o problems.

We I cut 0.75" A36 plate I will cover the material. Noise reduction is a big plus too. I keep ear muffs nearby too.

Good luck!

Tom

[Big John T]

Thanks Tom

John