We're beginning to see industrial 3D printers that work in metal, rubber and other materials that pose significant combustible dust hazards - most of which have not been evaluated.

Mike Wright

Michael J. Wright

Director of Health, Safety and Environment

United Steelworkers

412-562-2580 office

412-370-0105 cell

"My friends, love is better than anger. Hope is better than fear. Optimism is better than despair. So let us be loving, hopeful and optimistic. And we'll change the world."

Jack Layton

From: ACS Division of Chemical Health and Safety [mailto:DCHAS-L**At_Symbol_Here**PRINCETON.EDU] On Behalf Of Monona Rossol
Sent: Thursday, March 12, 2020 12:58 PM
To: DCHAS-L**At_Symbol_Here**PRINCETON.EDU
Subject: Re: [DCHAS-L] 3D printer emissions and UL 2904

This is one of the cases we don't depend on the manufacturers' recommendations. Most don't even acknowledge that there is any need for ventilation at all. As an example, the laser cutter makers addressed the problem with charcoal filters, which fail really fast when exposed to smoke and never capture some contaminants. They don't want to admit that ventilation is needed because it will reduce sales. Same with 3D printers.

As someone who sits on a lot of standards committees, you also need to be aware that the manufacturers are the major presences on these committees that set the product ventilation standards. So economics, which are not relevant to health issues, are a major driving force for setting UL, ASHRAE, and most standards.

That might be alright for adults, but if you are dealing with 3D printers in the schools where there are children and high risk individuals, go for 100 % exhaust to the outside. And this is easy and cheap in the long run. All it requires is an enclosure for the printer (some now come with enclosures) which is breached with a flexible duct and slow speed centrifugal fan and vented out of the building almost anywhere convenient that wouldn't return to the building. The 3D emissions are not regulated at this time, so you don't have to go to the roof. Out a nearby window or a wall penetration works.

The speed of the draw needs to be extremely low. All you need to do is keep the enclosure under negative pressure so it leaks in, not out. And this is also important because a rapid air flow would cool the head and affect the quality of the printed object.

You can also branch-duct a whole row of printers to one fan and exhaust.

We have been doing systems like this for 40 years with electric kilns. It may take a bypass box to damp down the flow low enough as it does with the kilns. But for the right industrial engineer, this is child's play. For most HVAC engineers, it is impossible.

Monona Rossol

-----Original Message-----
From: Chainani, Edward Torres <echaina2**At_Symbol_Here**ILLINOIS.EDU>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**PRINCETON.EDU>
Sent: Wed, Mar 11, 2020 3:30 am
Subject: Re: [DCHAS-L] 3D printer emissions and UL 2904

Thank you, Yaritza-I will determine the room volume of the intended location and compare with the model as you suggested.

It is likely that the authors of this UL standard didn't feel the need to address offensive odors, as there is a different standard, on ventilation for acceptable indoor air quality, that addresses that issue (ASHRAE 62.1).

I should have phrased my question this way: "Have any of you started vetting 3D printers based on the results generated according to this standard, as provided by the manufacturer?" I do not intend to be able to perform the test myself, as the methodology requires specialized equipment, and the list of target chemicals is extensive.

Regards,
Ed

On Mar 10, 2020, at 1:39 PM, Yaritza Brinker <YBrinker**At_Symbol_Here**FELE.COM> wrote:

Ed,

I saw this spec coming down the pipeline. We don=E2=80™t use it as it is intended to apply to the smaller consumer type 3D printers used for classroom, office, and home use. Also, it does not address any issues related to offensive odors.

While you could use this standard to test larger units used in industrial type settings/prototype shops, I don't quite see the point on testing those. Aside from the harmful emissions, 3D printers also have offensive odors. Large units can stink up a warehouse. So, these things should always be vented to the outside.

It looks like you can use the UL test data to decide if ventilation is "technically" required. Since the pass/fail criteria is expressed in emitted mass/room volume, I think you would need to look at Appendix B to ensure the model used to calculate the Pass/Fail criteria is applicable to your building. Looking at the residential model, my house is average for my area. However, it is smaller than the national average home used in the model. Thus, if I had a certified unit in my house, the actual exposure would be higher that the spec allows.

I suspect the UL spec will become a requirement for all 3D printers sooner or later. Until then, I'm asking for ventilation on ours.

By the way, I'm talking about plastic printers. 3D metal printers have no business being used without hard-plumbed ventilation regardless of their size.

Yaritza Brinker

260.827.5402

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