Got this response to my post about MAG's "no coolant" machining center. I'll repost the link to it below Dal's comments if you don't know what this about
"I am sure that you are aware that Nitrogen is not a "safe" gas. I do not know the statistics, but many fatalities occur every year because of nitrogen exposure. I do not know the process that is used in machining titanium, but I am sure that a single oxygen sensor (possibly with its own internal alarm) would not provide what I would call a safe environment safeguard in an indoor application. I would think that a dual or triple redundant sensor system with some sort of external TMR Safety system would be more appropriate to meet OSHA requirements. Probably an emergency exhaust system would be called for to be automatically tripped on by voting on several sensors. Certainly a HAZOP and SIL analysis on the process are in order. When employed by another company, we experienced a fatality on a man who simple stepped too close to an open flange on a vessel containing nitrogen in an outdoor environment. There is no warning smell or feeling. Many times the rescue persons) are killed trying to save the first one down.
I don't know if the vendor has thought of using compressed or liquid air as the cooling medium but that would make more sense to me. If the small quantities gases other than oxygen would be a refrigeration problem, perhaps a special mixture of 80% nitrogen and 20% oxygen could be used as the refrigerant. This would take all of the hazard away if the refrigerant is checked for composition as it is received and used. However, I am not a refrigeration engineer. Perhaps a mixture is impractical."
Joseph "Dal" Dalferes, PE, Principal Control Systems Engineer
Jacobs Engineering, 4949 Essen Lane, Baton Rouge, LA, 70809
225-768-8719 [email protected]
Here's the original posting with links:
After doing a bit more snooping around to try to confirm the freshness of the joint project between MAS-IAS; Creare, the cryogenics experts; and the U.S. Navy, to build a titantium machining center that doesn't use tool coolant [that's what I said, it doesn't use coolant], and doubles the rate of titanium cutting [ that's in 2x ] and increases ridiculously tool life, I'm still thinking this is an important industrial innovation that actually lives up to the word.
Don't know what I'm talking about?
Read: http://www.controldesign.com/articles/2010/ChangeGame1010.html
then
Watch: http://www.youtube.com/watch?v=KA8l-kx7nTQ&playnext=1&videos=rXWNj7iTCp0&feature=mfu_in_order
If you disagree, I'd really like to know why.
