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Old 2015-02-05, 12:05am
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Speedslug Speedslug is offline
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Join Date: Mar 21, 2009
Location: Winnebago, MN
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Lisa I knew some of the numbers in my head some 8 years ago when I was setting up my studio but, alas, the memory is the second thing to go as one ages.

You want to use the search term "cubic feet per minute" or just CFM to get you to the threads that talk about
1) the fumes created by the torch burning the fuel,
2) the gases given off from the glass as you heat it up to a molten state,
3) the dangerous gases that " fuming" with gold or silver will produce
4) the other dangerous gases from some of the trace metals used to give the glass its colors and
5) the problem of ventilation systems potentially causing the carbon monoxide and flue gases from you heating system or water heater coming back into your house instead of going up the chimney because your ventilation system is too strong.

I had a friend that installed this neato bitchen vent hood over their kitchen stove. It was a glorious stove hood and he got a great scratch and dent deal on it. Unfortunately it was strong enough to pull gases from his toilet drain lines and sink drain lines into the house. It took him a week to figure out why he had sewer gas in his kitchen and through out the house. He was pretty much pulling sewer gas out of the city lines in the street because his old house did not have the proper 'p' traps in the basement drains.

There is a balance involved with getting air out of the house. What ever you take out with studio torch ventilation needs to be replaced. The air you dump out side needs to be at least ten feet from where you get the "make up air".

Bringing fresh make up air right to your torch bench will keep you from robbing 'conditioned' air from you living spaces.

There are discussions about the size of the of air flow duct work and that changing from a 4 inch duct to an 8 inch duct increase the amount of air movement at a geometric scale.

I remember that six inch duct work was the smallest that some felt one was safe to use and that 8 inch duct work would work in most cases but if you are going to use bottled oxygen then you better go to10 or 12 inch duct work and increase the capacity of the fan system as well because huge flames create massive amounts of fumes.

There is a discussion abut the speed of air flow and a ratio of against the volume of air flow. I think the point there was an air compressor that you can use to fill your car tires can move air so fast that it can embed particles in to your skin but it the total volume of air is pretty small while a 24 inch box fan in the window can move a larger volume of air but it does not have enough force to fight a 5 mile an hour breeze coming back in the window.

I forget what size torch you will be running but that will have to be the major factor in figuring out how many "CFMs" the ventilation fan must have to be safe.

I do know that what ever size hole you have for the ventilation to leave the house you will need to have that size hole or larger for the make up air to get in.

Also save yourself the hassle at the start and get smooth wall ducting both for exhaust and for makeup air. The expandable stuff with the crinkly surface can get you by in a pinch but the crinkles in the surface slow the air flow so much that you could use 3 garden hoses and have about as much air flow. Don't bother with anything marketed for use with a dryer.
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Last edited by Speedslug; 2015-02-05 at 12:10am.
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