Air exaust system help needed.

[plain ol Bill]

I plan a 5'x10' plasma table and am torn between a fan exaust system and a water table. I have a 2600 CFM vaneaxial blower I could use for an air system. Have any of you folks designed an exaust system for your tables that you are happy with? I could use some advice and design tips.

[Torchhead]

If you can afford it do both! Each one does less than 100% for the smoke (which is vaporized metal....nasty, abrasive and conductive) and dust (larger particles of metal). The water table quinches the sparks and smoking drop outs, but does not kill the smoke under the material (between the material and the water) A downdraft system will remove most of the smoke but not stop the sparks. I finally gave up and built a containment room from heavy gauge plastic and used an exhaust fan to the outside AND kept the water tray. I have still had to replace three keyboards and mount the computer in a box with filters.

TOM CAUDLE
www.CandCNC.com

[jimcolt]

I agree with Tom....if you can design the system with water approx 6 to 12 inches below the top of the slats.....and pull a downdraft with your blower from above the water...then you will have a good system. Depending on what you are cutting....as much as 60% of the particles will be captured by the water....which makes taking care of the remaining 40% or so much easier.

Don't put a hood over the machine to pull the fumes upward.....you will simply be pulling all of that abrasive dust over the moving parts of your machine. Too many people have updraft systems with plasma....what a mess!

Jim Colt

[plain ol Bill]

I like the idea of using air and water both to get rid of fumes and dust. I know how nasty plasma is from years of manually using one in my shop. Now for another question guys - The table I am planning is 5x10 and if the water level is say 10 - 12 inches below the bottom of the slats where would you put the air intake into the table? I would "presume" to put it in on the "off" side of the table at the 5 ft. center point. Would you cover any area of the table not w/ something to localize air evacuation from the area being used?

[Big John T]

Air will flow from high pressure areas to low pressure areas via the path of least resistance. What does this mean in English? If you have a suction opening near one edge and you have a space between the plate and the opening much of the air will flow from the top through the opening to the suction pipe. If you want air to flow under the plate from one side to the other the smaller the gap between the suction side of the plate and the machine the more air will come from the other side. Also make sure you have enough make up volume of air coming from the opposite side of the suction opening.

John

[douglasco]

Originally Posted by jimcolt Don't put a hood over the machine to pull the fumes upward.....you will simply be pulling all of that abrasive dust over the moving parts of your machine. Too many people have updraft systems with plasma....what a mess! Jim Colt

Has anyone tried running a flexible hose from up high and mounting it to the z? Like on a router table? Maybe a plasma moves too fast or the issue is a fire resistant hose?

[plain ol Bill]

My build has started and I have gone with a water table exclusively. I really think this will remove 99.5% of airborne crap.