Hi Monona, The hypothetical of incompatible exhaust streams is difficult to answer.

Instead, I would put those considerations into design - for instance, what could be the worst result? Fire, corrosion, something else.

Is there fire protection, anti-corrosion surfaces?

Consider designing the duct so that it can be inspected periodically and perhaps cleaned at 5 or 10 year intervals.

Allowing them to be disconnected in sections or at the instrument and rinsed with water, disposing of the water in accordance with all local regulations.

James

Hi Monona,

 

It would seem to me that the hazards of ventilating these two laser cutters together should be minimal (though I don=E2=80™t have any data to "prove" this) since as you note the metal fume should be metal oxide fume almost immediately I would think.  One suggestion could be to restrict metal cutting to only be done on the laser cutter furthest downstream aka closest to the exhaust?  Though wood particulate from the other LC could still intermingle so maybe this would make no difference.  And any "restriction" like that would likely only work in a staffed space...much more difficult in a student-run environment (though possible with diligent enough students).

 

I'm just glad to hear they (whoever They are) are going to ventilate their laser cutters properly with ducted exhaust!

 

Dan

 

(from the ACS National Meeting in Boston where I've been extolling the virtues of DCHAS, in particular the DCHAS-L as an amazing resource (thanks to Ralph and Rob and the many others who help make the listserv go), and where Monona Rossol's name has come up several times as an amazing resource as well)

----------------------------------

Daniel C. Herrick, CIH

Senior EHS Coordinator, MIT MechE

herrickd**At_Symbol_Here**mit.edu

617-253-2338; Room 3-449g

http://ehs.mit.edu

On Aug 21, 2018, at 7:56 AM, DCHAS Membership Chair <membership**At_Symbol_Here**DCHAS.ORG> wrote:

From: Monona Rossol <actsnyc**At_Symbol_Here**cs.com>
Re: Need help on a ventilation problem

I've been asked if two large laser cutters can be branch-ducted together. The problem is they will be used to cut wood, plastic, leather, and metal at various times. This means metal fumes can be in the ducts at the same time as smoke from potentially combustible materials. Since the metal will be in a fume, that is, a metal oxide form, it isn't clear that the combination would be hazardous.

Any and all opinions on the potential hazards or lack thereof are eagerly awaited.

Monona Rossol in Amherst teaching the art safety course.

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