From: edward sage <sage7652**At_Symbol_Here**BELLSOUTH.NET>
Subject: Re: [DCHAS-L] Need help on a ventilation problem
Date: Fri, 24 Aug 2018 23:49:01 +0000
Reply-To: edward sage <sage7652**At_Symbol_Here**BELLSOUTH.NET>
Message-ID: 1134227037.3528639.1535154541540**At_Symbol_Here**mail.yahoo.com


Monona,

Have there been enough studies done on the gas phase products of cutting various materials with large laser cutters to really answer your original question? Somehow I doubt it.

Two specific examples come immediately to mind. First, given the multiple oxidation states possible with many metals, I have to wonder if reactive species including nitrides might be formed. Second, given the amazing thermal stability of TCDD, does it form during the cutting of chlorine-containing materials such as PVC or PVDC.

One example I did find is given below.
https://www.researchgate.net/publication/233244349_Laser_cutting_of_Kevlar_A_study_of_the_chemical_by-products

Ed Sare
--------------------------------------------
On Fri, 8/24/18, Monona Rossol <0000030664c37427-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU> wrote:

Subject: Re: [DCHAS-L] Need help on a ventilation problem
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Date: Friday, August 24, 2018, 4:54 PM

The only thing I am
concerned about is the fire or explosion hazards. I think
there probably are none but don??t want to be wrong.
Monona


-----Original Message-----
From: James Saccardo

To:
DCHAS-L
Sent:
Fri, Aug 24, 2018 02:39 PM
Subject: Re:
[DCHAS-L] Need help on a ventilation problem






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



From: ACS Division of Chemical Health
and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU]
On Behalf Of Michael

Sent: Tuesday, August 21, 2018 8:49 AM

To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU

Subject: Re: [DCHAS-L] Need help on a ventilation
problem




Try contacting the
manufacturer of the LCs. Equipment manufacturers will often
sell local exhaust attachments for their machines or tell
you who might.





Mike Buczynski


Sr EHSAdvisor
Product Stewardship,Regulatory Affairs


Afton Chemical


Richmond VA




On Aug 21, 2018, at 8:42 AM, Daniel C Herrick
wrote:



Hi Monona,




It would seem to
me that the hazards of ventilating these two laser cutters
together should be minimal (though I don??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
wrote:



From: Monona
Rossol


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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