Plasma Table Exhaust fan into water trap?

[Jduke]

I previously had a water table and got decent results in fume/spark control.

I sold that table and made a downdraft table because I use my table fairly infrequently.

My shop is air conditioned so I don’t want to exhaust outside, add to that we frequently get dry enough that a grass fire is a concern.

I’d like to stay with downdraft, but need a way to decrease fumes and fire risk.

I have a 13gallon harbor freight dust collector that pulls the fumes in, exhaust is where I’m going to have trouble.

Has anyone tried putting the exhaust into a barrel of water as sort of a water trap?
Does it work ok ? Any problems I should try to avoid?

Thanks
Duke

[adbuch]

I seem to recall seeing some photos of a system where the exhaust was ducted outside thru the wall, and then it turned at 90 degrees and was pointing down into a water trap. I think this was just a container filled with water. Apparently most of the smoke and debris was trapped by the water. In this particular case I think the owner was attempting to mitigate airborne contamination drifting into his neighbor's yard. It would certainly be worth a try, and it must might work with the trap indoors as well. Maybe do a google search to see what you come up with.

David

[weldguy]

I have also seen that done and appeared to work really well.

[N2 Welding]

What is the principle of the design? Does the exhaust pipe get plumbed into a bucket of water where the exhaust is say 3” inches below the water level so that it will bubble through the water trapping the toxic gasses in the water?

[Jduke]

I was thinking about just putting the exhaust pipe at the water surface, or maybe just far enough that it splashed the water pretty vigorously around a semi enclosed bucket.

I am guessing this will increase humidity in my shop if I run it much.
Although the AC should dehumidify fairly well.

[adbuch]

What is the principle of the design? Does the exhaust pipe get plumbed into a bucket of water where the exhaust is say 3” inches below the water level so that it will bubble through the water trapping the toxic gasses in the water?

No - exhaust exits above the water surface.
David

[plasmajoe]

I operate a Tracker downdraft table, dust was an issue with my neighbors, and that is exactly what I did. Built a water trap and dust collector outside my shop. I have a 12" piping system that I reduced to 8" crating a strong force in my first 45 gallon drum with another 8" elbow exhausting out into another line to another 45 gallon drum both are filled 3/4 of the way up with water. end of open elbow is around 2-3 inches from the surface of the water. On the second barrel exhausting out, very little dust/particles escape. I also built a shed 6'x12' filled with filter cloths with one 16x16 filtered opening to let all exhaust out. No more particles floating in the air and now my neighbors dont even know when I'm running. My shop is sound barriered and now particle free. To answer your question, yes it does work very well, you will have to keep an eye on your water level and have room to put all the components in place.

Plasma Joe

[Joe Jones]

My plasma table has a 36" diameter high volume fan that exhausts the smoke and dust into a large, sealed and insulated plywood room on the outer wall. The room is 144" x 96" x 76" The room walls and ceiling are lined with thin sheet metal. There is a thick framed and insulated door for entry into the "dust collector room."

There are four LARGE filter screens (24"x36") that allow the dirty air blown into the room, to return to the plasma table work area through the same wall, after the air passes through three-stage filters. I use a large fiber filter, a large plastic mesh filter, and a large commercial stainless steel commercial kitchen grill filter in each window.

The stainless steel grill filters were $96.00 each. They are normally seen in the huge stainless steel vents over the stoves and grills of restaurants and fast food joints. They can be taken down and cleaned with a power washer (at a car wash), and reused indefinitely.

The plastic filters that are similar to the green pot scrubber pads are 3/4" thick. They catch finer dust. They can be hosed clean and reused for a long time, but eventually deteriorate and must be replaced.

The final fiber filter is on the inside. It is the typical air filter you us in your home for the HVAC air intake. They catch anything that got past the first two filters. They are cheap to buy IN BULK, and easy to replace. I know when they need to be replaced, because they will clog up and be blown through the frame merely from the air pressure in the room.

The smoke and heavy dust hits the back wall of the dust room and falls to the floor, and becomes "moon dust" on the floor in a drift against the wall that can be shoveled up,and picked up with a shop vac that also has an appropriate filter to save the vac motor. The finer dust is captured by the steel filters and the plastic mesh filters. The finest particles are captured by the fiber filters. All three filters must be the same size.

Both HEAT and COOL AIR are blown into this sealed room from beneath the plasma table, and returned to the shop area, cleaned of all of the cr*p in the air. This room works sort of like a paint booth.

One or two small vibrators can be attached to each metal screen with zip ties or hot glue, etc. A timer causes the vibrators to shake the metal screens once per (time unit) and allow the metal dust that has collected onto them to fall to the base, and onto the floor.

The "dust room" must be cleaned out once in a while, of course.

Joe

The images below are just EXAMPLES of the filters I use and are not the actual dimensions, or the actual products I buy.

VIBRATING MOTORS.jpg

The TYPE of filters I bought, but mine are larger.

STEEL AIR FILTERS.jpg

The mesh filter material

mesh filter.jpg

FINAL FILTER

FINE FILTER.jpg

[adbuch]

What is the principle of the design? Does the exhaust pipe get plumbed into a bucket of water where the exhaust is say 3” inches below the water level so that it will bubble through the water trapping the toxic gasses in the water?

The one I saw had the exhaust pipe above the water level. But it did seem that most of the particles were trapped by the water surface
David

[SegoMan DeSigns]

Get an old evaporative (swamp) cooler and reverse it's flow, or completely remove the squirrel cage and blow through the wet media only. The media is cheap to replace and flush out with water.

[Joe Jones]

What is the principle of the design? Does the exhaust pipe get plumbed into a bucket of water where the exhaust is say 3” inches below the water level so that it will bubble through the water trapping the toxic gasses in the water?

No, a water trap works like the small ones people use inside of apartments with clothes driers. The air is directed at a surface of water. The THEORY is that the particles in the air (lint fibers, or smoke and plasma dust, etc.) are too heavy to make a sudden right angle turn above the water's surface, so they basically "crash" into the water as the air is blown at it, while the clean air successfully deflects 90 degrees back into the room. It is like the speeding car that runs into a sharp turn It runs off of the road because of the inertia. A water trap works the same way.

Joe

[adbuch]

Get an old evaporative (swamp) cooler and reverse it's flow, or completely remove the squirrel cage and blow through the wet media only. The media is cheap to replace and flush out with water.