New plasma table with water bed questions ...

[Dustin407]

My table has a 10" deep 4x8 water table with a 200 gal overflow tank and small submersible pump so I can regulate water height.... It can be any depth really... 2" or 3'... If you have a small table 4x4 make it deeper to keep the water cooler (it will get very hot over time especially when you have to grab a small part in the tank) All it is for is to catch the vaporized metal dust( take it out of the air), and keep the material like stainless from warping... fill the water all the way up to the bottom of your cutting material so it touches... seems to work nice.. I would go 6"-8" if I was you

[diyengineer]

Originally Posted by Jcar Bearracecars, After reading through the PDF files, I've apparently mixed the two companies up. The agitators were in a PDF that I found on Hypertherm's site. Here's a link. https://www.hypertherm.com/library/f...)/800270r1.pdf About 2/3 of the way through the document you'll find a section titled "Aeration Manifold For Cutting Aluminum With Plasma". I wish I had thought of installing my input and exhaust air valves on opposite ends of the tank. Smart thinking.

I will have to check this out. I'm building a plasma JUST to cut aluminum. I'm currently at work so i can't download the PDF. From what i have seen online, people use a waterbed with aluminum just fine. Is the hydrogen gas buildup they speak of superheated water that explodes or what is the deal?

[jimcolt]

This is a "canned" response from my files.....as questions pertaining to cutting aluminum with plasma over a water table are asked quite frequently"


Jim

In regards to cutting aluminum over a water table, there generally is no concern of the possibility of hydrogen production and the ensuing explosion hazard. Aluminum cutting produces a by product of aluminum oxide, which sinks in the water and absorbs oxygen. When oxygen is removed from water (H20) it leaves hydrogen, which you will see rising to the surface (after cutting aluminum) as small bubbles.

Since the quantity is very small, and hydrogen is lighter than air, the small amount of hydrogen will dissipate in the ambient air.

Many water tables have a submerged chamber that is used (with compressed air) to rapidly raise and lower the water level in the table for small parts removal, cleaning, etc. If aluminum oxide is allowed to get into a closed chamber, hydrogen could be trapped and over time could form a large pocket, and with the event of a spark and some oxygen there could be an explosion.

Most of the stories about aluminum and water tables causing explosions have no basis, although there have been a couple of issues over the 32 years I have been working for Hypertherm that involved minor explosions on large industrial machines. The ones that I am aware of were solved with aerators (no pump needed) that simply involved a couple of pipes with holes drilled in them in them...submerged in the water table. Low pressure compressed air was fed into the pipes to aerate the water, diluting the hydrogen.

Cut all the aluminum you want on small water tables!

Jim Colt Hypertherm

Originally Posted by Jcar Bearracecars, After reading through the PDF files, I've apparently mixed the two companies up. The agitators were in a PDF that I found on Hypertherm's site. Here's a link. https://www.hypertherm.com/library/f...)/800270r1.pdf About 2/3 of the way through the document you'll find a section titled "Aeration Manifold For Cutting Aluminum With Plasma". I wish I had thought of installing my input and exhaust air valves on opposite ends of the tank. Smart thinking.

[Dustin407]

Two things 1) keep your water table open no chambers to trap gases 2) Dont allow the water to sit up to the bottom of the material over long periods of time. The water could seal under the material and create a small air pocket underneath especially if material is slightly warped domed shaped, first pierce kaboom... Keep water about 1/8" below material and youll be fine.

My watertable is alum. and I cut alum. all day with no problems... Because I follow rule 1 and 2... lol

[diyengineer]

Good to know thank you both!

Originally Posted by jimcolt This is a "canned" response from my files.....as questions pertaining to cutting aluminum with plasma over a water table are asked quite frequently" Jim In regards to cutting aluminum over a water table, there generally is no concern of the possibility of hydrogen production and the ensuing explosion hazard. Aluminum cutting produces a by product of aluminum oxide, which sinks in the water and absorbs oxygen. When oxygen is removed from water (H20) it leaves hydrogen, which you will see rising to the surface (after cutting aluminum) as small bubbles. Since the quantity is very small, and hydrogen is lighter than air, the small amount of hydrogen will dissipate in the ambient air. Many water tables have a submerged chamber that is used (with compressed air) to rapidly raise and lower the water level in the table for small parts removal, cleaning, etc. If aluminum oxide is allowed to get into a closed chamber, hydrogen could be trapped and over time could form a large pocket, and with the event of a spark and some oxygen there could be an explosion. Most of the stories about aluminum and water tables causing explosions have no basis, although there have been a couple of issues over the 32 years I have been working for Hypertherm that involved minor explosions on large industrial machines. The ones that I am aware of were solved with aerators (no pump needed) that simply involved a couple of pipes with holes drilled in them in them...submerged in the water table. Low pressure compressed air was fed into the pipes to aerate the water, diluting the hydrogen. Cut all the aluminum you want on small water tables! Jim Colt Hypertherm