plasma water tank

[snaggletto]

Hello,
I'm needing to build a water tank to put under my plasma table to catch slag and hopefully reduce smoke etc...

1. How far below the surface of the material should the water be?

2. How deep or how shallow can the water be so that the tank won't be so heavy?

3. Any specific design recomendations or plans/drawings available?

Thanks for any input.

[svenakela]

Hi,

As far as i know, plasma cutters are moist sensitive.
I know a simple second solution (I'm not saying yours is bad, it's just a second way ), make a dish out of thin metal sheet with 5-10cm (2-4") high sides and put a couple of buckets of sand in it. When you cut a lot you can spray some water on the sand.

Cheers,
Sveb

[whiteriver]

I'm not so sure about moister sensitive. Where I buy most my steel they have a 8'x20' plasma cutter that if I recall correctly has a 2" cut capacity. Anyway to keep noise fumes and the light down they cut under water. Have a large tank with a pump on it. Lay the metal down on the finger table then hit the switch. Tank fills with water. It produces a few bubbles and works great. The operaters only problem is you can't see the cut so you don't know if you have a bad tip till your done. I have watched it work a few times. Just bough a buch of plased circles in 3/8" thick for a current project and they look good.

Donny

[Al_The_Man]

The Plasma water tables I have come across cut around 1/2" under the water , I don't think the depth under the plate matters, I believe they use the same method that submarines use for quick ballast dumping. i.e. compressed air tanks to refill quickly between jobs.
Al

[metlmunchr]

The moisture sensitivity is with the air being supplied to the plasma cutter from the compressed air system. They're very sensitive to moisture in that respect, but not sensitive to moisture in their surroundings.

[snaggletto]

Hey,
Maybe I'm mistaken. I was told to put the water tank under the material. In other words, the material sits 3-5" (or whatever) ABOVE the surface of the water at all times. I know some of the big/professional tables cut under water, but I'm talking about cutting above the water. Will this be of any benefit? Maybe I just misunderstood.

[Al_The_Man]

Yes, your right, moisture in the gas line, especially if you are using compressed air shortens the life of consumables , and they are not usually cheap!
Al

[metlmunchr]

Having water under the material should help a lot. I know it does on my oxy-fuel burning table. Most commercial plasma tables in the lighter capacities are set up with a draft table to suck away the dust and fumes. Most folks i've seen mention using a setup like this on a home system are trying to do it with too little fan, so it ends up ineffective. There's a definite threshold for perimeter capture velocity for a device like this (similar to a commercial range hood in that respect) and if you're much under that velocity the stuff just goes wherever it wants to even if the fan is running.

[Ries]

I have been running a water table on my plasma cutter for over 10 years now, and I highly recommend it. I built a steel tank about 6" deep, out of 1/8" plate. I took two pieces of 3" angle, the length of the tank, and plasma cut slightly angled slots in them to recieve 1/4" x 3" flat bars the width of the tank, about 2" apart. Slight angle off of straight up and down allows slag to fall off, and makes it easier to drag sheet across. Fill up the tank with water to just about level with the top of the slats. Yes, you can run the metal you are cutting slightly below water level, but I usually try to run it a 1/4" or so above water level. The water catches all the sparks, which are actually gritty slag. And it catches all the red hot drops from interior cuts, which otherwise you would step on, or might catch your floor on fire. It cuts down greatly on smoke.
Make sure you put levelling feet on your water table, especially if you dont have auto torch height, but even if you do. You want the table nice and flat in relationship to your torch. Also make sure you put a hose bib- a faucet, if you will, at the low point underneath the table, so you can hook up a hose and drain the table once or twice a year. With a wire mesh screen over the drain, so it doesnt fill up with mud. The water will be horribly cold when you have to reach in and fish out a piece that you wanted that fell in. And it will fill up with nasty mud like slag stuff, which is one of the dirtiest substances on earth, when you have to clean it out. But all of that nasty stuff would otherwise be on your floor and in the air in your shop, so it is definitely worth building one. Water is heavy- a pint is a pound, the world around. No two ways about it. But a water table will do 75% as well as a 5000 dollar fume extraction system, and only cost a couple of hundred bucks to build.

[Al_The_Man]

Originally Posted by Ries - a pint is a pound, the world around. .

Only in the US. Most everywhere else its a pound and a quarter (20ozs).
Al

[Txfatboy]

Would the table work as well if it were only 3 " deep and also does it miniumize warping even if you are cutting above the water?

[thielert]

Asking what Txfatboy just did, only different..

Is the need for an auto height torch as great when cutting above a water table?
Is an auto height torch needed at all when cutting below water?

Will your common Hypertherm 600 plasma cutter work under water or is this discussion specific to the industrial machines?

Thanks, I love this discussion, so little info on plasm cnc out there. I'm considering adding plasma to my 4'x4' table. Just need to run a 220v circuit to the garage.

TT