I'm going to do a little math problem to show you what you're up against.

The PEL for Cr[VI] is 5 micrograms/m^3.

Lets plasma cut a 1/8" thick sheet of 304SS.

304SS is 18-20% Chromium. We will assume it is 19% for the calculation.

We will also assume that in the plasma arc, all metalic chromium is oxidized to the +6 valence. We will use a 1/8" kerf for the calculations as well.

SS has a density of 8000kg/m^3 or 8g/CC. So each CC of stainless has 19% of 8g, or 1.52g chromium.

A cut 1/8" thick by 1/8" wide is .32cmx.32cm. To get 1CC, the cut needs to be 1/(.32^2) or 9.76cm long. This is 3.84" long. This is how long the cut must be to vaporize 1 CC of stainless (which vaporizes 1.52g of chromium).

1.52 grams is 304,000 times 5 micrograms, so you'd need to dilute it in 304,000 cubic meters of air to meet the PEL of 5ug/m^3.

Assuming 16' tall ceilings (4.88m), the empty building of air needed to dilute this amount of chromium would have to be 62,300 sq meters or 671,000 sq feet. This is a 15.4 acre building with 16' high ceilings.

Even if only 1% was oxidized to +6 and suspended in the air, you'd need 6,700 sq feet to dilute it to the PEL!

And thats for cutting about 4" of 1/8" stainless.

How much do you cut in a typical project? 10 feet? 100 feet?

A football field (including end zones) is 360'x160'. If you cut 100 feet of 1/8" stainless, and only 1% stayed airborne, you'd need the air contained over 36.4 football fields with a 16' ceiling to dilute it to the PEL.

So cutting, grinding, and stick welding will put you way over the PEL in a hurry. And drawing it out with negative pressure will put the people downwind above the PEL. But the PEL is so low that even TIG welding might do it.

I'm glad I didn't pi$$ off whoever you pi$$ed off!

The PEL for Cr[VI] is 5 micrograms/m^3.

Lets plasma cut a 1/8" thick sheet of 304SS.

304SS is 18-20% Chromium. We will assume it is 19% for the calculation.

We will also assume that in the plasma arc, all metalic chromium is oxidized to the +6 valence. We will use a 1/8" kerf for the calculations as well.

SS has a density of 8000kg/m^3 or 8g/CC. So each CC of stainless has 19% of 8g, or 1.52g chromium.

A cut 1/8" thick by 1/8" wide is .32cmx.32cm. To get 1CC, the cut needs to be 1/(.32^2) or 9.76cm long. This is 3.84" long. This is how long the cut must be to vaporize 1 CC of stainless (which vaporizes 1.52g of chromium).

1.52 grams is 304,000 times 5 micrograms, so you'd need to dilute it in 304,000 cubic meters of air to meet the PEL of 5ug/m^3.

Assuming 16' tall ceilings (4.88m), the empty building of air needed to dilute this amount of chromium would have to be 62,300 sq meters or 671,000 sq feet. This is a 15.4 acre building with 16' high ceilings.

Even if only 1% was oxidized to +6 and suspended in the air, you'd need 6,700 sq feet to dilute it to the PEL!

And thats for cutting about 4" of 1/8" stainless.

How much do you cut in a typical project? 10 feet? 100 feet?

A football field (including end zones) is 360'x160'. If you cut 100 feet of 1/8" stainless, and only 1% stayed airborne, you'd need the air contained over 36.4 football fields with a 16' ceiling to dilute it to the PEL.

So cutting, grinding, and stick welding will put you way over the PEL in a hurry. And drawing it out with negative pressure will put the people downwind above the PEL. But the PEL is so low that even TIG welding might do it.

I'm glad I didn't pi$$ off whoever you pi$$ed off!

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