We design both chemical fume hoods as well as other containment devices used for processing powders and nano chemicals. There are differences in behavior of gases and particles
that influence how we test units that simultaneously have gas and particle applications:
1)
Because of their potential electrostatic properties, powders may cling to surfaces like airfoils, baffles, internal exhaust duct parts, or sash handles.
2)
Gas molecules and fine powders have different Brownian movement and other inter-particle attractive forces which affect how they are removed from a containment space.
3)
In the case of "containment loss", small particles will remain in the room on surfaces, while gases will eventually "leave the stadium" through dilution.
If we are challenged with a particle/gas containment application, Flow Sciences will always recommend testing our final proposed hood with both ASHRAE 110 (gas/vapor)
and a surrogate powder test where our test room is first thoroughly cleaned, then simulated customer procedures are tested, and the test room air sampled with devices that filter key areas in our test room air during the procedure. These filters are
then independently tested to determine if the test powder is present in any of the sampling spots in our test room.
It is obviously our long term goal to have the simplest possible test for mixed-use applications, but so far, the empiricist approach seems to give the best answer for our customers.
Very Truly Yours,
Dr. Bob Haugen
Director of Product and Technology Development
Flow Sciences Inc.
2025 Mercantile Drive
Leland, NC 28451
Phone 910 332 4878
From: DCHAS-L Discussion List [mailto:]
On Behalf Of Monona Rossol
Sent: Thursday, August 06, 2015 9:27 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L] Fume Hoods
One more person agrees that it doesn't make sense for whatever that's worth.
Monona Rossol, M.S., M.F.A., Industrial Hygienist
President: Arts, Crafts & Theater Safety, Inc.
Safety Officer: Local USA829, IATSE
181 Thompson St., #23
New York, NY 10012 212-777-0062
-----Original Message-----
From: Tobias, Bruce <btobias**At_Symbol_Here**WELLSTAT.COM>
To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Sent: Thu, Aug 6, 2015 5:33 am
Subject: Re: [DCHAS-L] Fume Hoods
David - I agree that lower face velocity recommendations for nanoparticles do
not make intuitive sense. ANSI/ASHRAE 110 uses a tracer gas to test containment
in chemical fume hoods. Surely nanoparticles are no harder to contain than
gases.
I would love to see the supporting data behind any recommendation to
use lower airflow when working with nanomaterials. Weighing dry nanomaterials,
of course, would be another matter entirely.
-----Original
Message-----
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**med.cornell.edu] On
Behalf Of David C. Finster
Sent: Wednesday, August 5, 2015 1:17 PM
To:
DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L] Fume Hoods
Debbie, and
others,
This makes (some) sense to me; I understand that nanoparticles that
are not in some matrix are prone to easy dispersal. What puzzles me is: if
these tiny particles can "blow around" easily, surely they don't "blow around"
more easily than some gas (NO2, H2S, etc) - do they? Could they? Seems to me
that tiny molecules and tiny nanoparticles would behave about the same in this
regard. Thus, if a "high" flow rate of 100 fpm is inappropriate for
nanoparticles due to "excess turbulence" (I'd guess) then why would this not
also apply to "regular" gases?
If we empirically KNOW that the lower flow
rate for nanoparticles is appropriate then this a good guideline, of course. It
just doesn't make intuitive sense to me.
Dave
David C.
Finster
Professor, Department of Chemistry
University Chemical Hygiene
Officer
Wittenberg
University
937-327-6441
https://urldefense.proofpoint.com/v2/url?u=http-3A__userpages.wittenberg.edu_dfinster_index.html&d=BQIFAg&c=lb62iw4YL4RFalcE2hQUQealT9-RXrryqt9KZX2qu2s&r=meWM1Buqv4IQ27AlK1OJRjcQl09S1Zta6YXKalY_Io0&m=6BYvX8ZkifTQ2lIzlAHkyM7YZJ3y5_uVk44suyTlm84&s=SuVStqlUpFPjKAEmAumtf8elM-UbrmIDAeSkVmUyhcA&e=
-----Original Message-----
From: DCHAS-L Discussion List
[mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Debbie M. Decker
Sent: Tuesday,
August 04, 2015 11:51 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L]
Fume Hoods
If they're working with unbound (neither on a matrix nor in
solution) engineered nanomaterials, lots of air flow can blow the nanoparticles
around and create an exposure situation. Because nanoparticles are so small,
their properties, loose in the air, are atypical and once airborne, are
difficult to capture again.
AirClean, Labconco, and most of the other fume
hood manufacturers market nanoparticle containment devices, that have HEPA
filters and recirculate filtered air back into the lab. Typical of Labconco,
their offering seems to be particularly well-engineered.
And now, I'm going
to be quiet because that's about the extent of my expertise on this
topic!
HTH,
Debbie
<usual disclaimers apply>
-----Original
Message-----
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On
Behalf Of David C. Finster
Sent: Tuesday, August 04, 2015 6:51 AM
To:
DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L] Fume Hoods
Can someone offer
an explanation for the lower-than-usual flow recommendation when using
nanomaterials?
Thanks.
Dave
David C. Finster
Professor, Department of
Chemistry
University Chemical Hygiene Officer
Wittenberg
University
937-327-6441
https://urldefense.proofpoint.com/v2/url?u=http-3A__userpages.wittenberg.edu_dfinster_index.html&d=BQIFAg&c=lb62iw4YL4RFalcE2hQUQealT9-RXrryqt9KZX2qu2s&r=meWM1Buqv4IQ27AlK1OJRjcQl09S1Zta6YXKalY_Io0&m=y90GGN5CEc9Pr_2WVgV7Iw-4FSDM50IlraVESOYSr60&s=5-AUlno8fmWnamzuNqB5ofnjkIestbMYnkN01g_Nb-U&e=
-----Original Message-----
From: DCHAS-L Discussion List
[mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Ray Ryan
Sent: Monday, August 03,
2015 10:38 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L] Fume
Hoods
Luis is correct, low flow down as low as 50LFPM would be best working
with nano-materials.
Best regards,
Raymond Ryan, CEO
Flow Sciences,
Inc
2025 Mercantile Drive
Leland, NC
28451
910-200-4239
rryan**At_Symbol_Here**flowsciences.com
www.flowsciences.com
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-----Original Message-----
From:
DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**med.cornell.edu] On Behalf Of Luis A
Samaniego
Sent: Monday, August 03, 2015 9:22 AM
To:
DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re: [DCHAS-L] Fume Hoods
For nanomaterial
work, it may require a lower fpm than the 80-100 fpm. Check with the fume hood
manufacturer for proper face velocity if this is the case.
Luis
Samaniego
Sr Laboratory Safety Specialist
Northwestern University
Office for
Research Safety
303 East Chicago Avenue
Ward B-106, W223
Chicago, IL
60611
(312)503-8300
-----Original Message-----
From: DCHAS-L Discussion
List [mailto:dchas-l**At_Symbol_Here**med.cornell.edu] On Behalf Of Czerwinski, Kevin
Sent:
Saturday, August 01, 2015 7:33 AM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: Re:
[DCHAS-L] Fume Hoods
Also depends on jurisdiction. State facility in a
non-OSHA state? For example, state law in Wisconsin is 100 fpm.
Dr. Kevin
M. Czerwinski, Ph.D.
Professor
Department of Chemistry
University Chemical
Hygiene Officer
Environmental Health and Safety
B150 Science
Building
University of Wisconsin-Stevens Point
2001 Fourth Avenue
Stevens
Point, WI 54481
715-346-4154 (Office)
715-340-2216 (Mobile)
> On Aug 1,
2015, at 7:20 AM, Ellen M. Sweet <ems325**At_Symbol_Here**CORNELL.EDU> wrote:
>
> Kevin,
>
The 80-120 fpm range, from the ANSI Z9.5, is based on performance (containment).
The standard also states that some hoods will perform at lower face velocities.
Your organization needs to decide what face velocity you want your hoods at,
unless you're in California.
> 100 fpm is typical.
>
> Ellen
>
>
-----Original Message-----
> From: DCHAS-L Discussion List
[mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Kevin Burns
> Sent: Friday, July
31, 2015 10:17 AM
> To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
> Subject: [DCHAS-L] Fume
Hoods
>
> I am currently finding myself in trying to deal with a fume hood
problem. We had a mechanical problem that needed to be repaired causing The
system to be shut down. Now that the system can be turned back on we need to
have an air balancer come in and rebalance the system. After that my
certification company would come in to certify that the hoods are maintaining
proper CFMs for employees to work in them within the laboratories. The air
balancer is in disagreement with the certification vendor. The air balancer says
we have to have a policy that our face velocities for each hood must be 100cfm,
where the certifiers are indicating that it's between 80 and 120 which that was
what my understanding was.
>
> I know this falls under ASHRAE standards,
ANSI standards and OSHA standards, can you point me in the right direction of
where to get the exact information?
>
> Thank you, any information would
greatly be appreciated.
>
> KB
>
> Kevin Burns
> Sent from my
iPhone
--