Air filters for microscopy rooms, which class?

[Steffen Dietzel]

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Dear All,

could you let me know with which type of air filters for the ventilation
of microscopy rooms you have good or bad experiences?

Apparently we already have an F7 and F9 filter in the ventilation inlet,
but we still collect quite a bit of dust over time. So I would like to
get an additional filter into the incoming air shaft. But which one? If
I understand filter classes correctly, the next best thing above F9 is
already a HEPA filter, but they come in classes from E10 to U17. Before
requesting a specific filter class,  I would like to tap into your
experiences to hopefully make a more substantiated decision.

Best

Steffen

--
------------------------------------------------------------
Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Biomedical Center (BMC)
Head of the Core Facility Bioimaging

Großhaderner Straße 9
D-82152 Planegg-Martinsried
Germany

http://www.bioimaging.bmc.med.uni-muenchen.de

[samjlord]

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I'm not sure what you mean by "inlet." I don't think you need to filter the air flowing back into the HVAC system for the entire building, because I don't think that will have any noticeable effect on the dustiness in your room. You should install filters on the air source (outlet). I found a HEPA filter that fit the vents in my lab and duct tape it on there:

http://blog.everydayscientist.com/?p=3488

I happened to use a 20x20x1 Synthetic Pleated Air Filter with MERV 13 level filtering. It doesn't impede the airflow significantly, which is important because I want to maintain positive pressure in the room (to keep dust from coming in from the hallway).

I have found that that filter noticeably reduces the dustiness in our scope room!

Sam

[Craig Brideau]

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Keep in mind much of this is moot if you don't have decent sealing in the
room. If you have many air gaps (door frames, ceiling tiles, etc) you will
have ingress of dust regardless of your filters. You can mitigate this by
having the room at positive pressure, that is more air enters the room than
is purposely exhausted. This keeps the air constantly blowing OUT any gaps
and prevents dust ingress. There is a problem with this though, as to
maintain positive pressure you need sufficient air flow into the room. If
your filters are very aggressive, they will cause a large pressure drop
across themselves as the ventilation fans attempt to force clean air into
the room. In effect, the smaller particle filtering, the higher the
pressure drop across the filter, and the stronger fans you need to actually
drive air across them to get the necessary positive pressure into the room.

Craig


On Tue, Sep 11, 2018 at 10:38 AM Sam Lord <[hidden email]> wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> I'm not sure what you mean by "inlet." I don't think you need to filter
> the air flowing back into the HVAC system for the entire building, because
> I don't think that will have any noticeable effect on the dustiness in your
> room. You should install filters on the air source (outlet). I found a HEPA
> filter that fit the vents in my lab and duct tape it on there:
>
> http://blog.everydayscientist.com/?p=3488
>
> I happened to use a 20x20x1 Synthetic Pleated Air Filter with MERV 13
> level filtering. It doesn't impede the airflow significantly, which is
> important because I want to maintain positive pressure in the room (to keep
> dust from coming in from the hallway).
>
> I have found that that filter noticeably reduces the dustiness in our
> scope room!
>
> Sam
>

[Steffen Dietzel]

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Sam, Craig,

thanks for your comments. Sorry if I got the engineering terms wrong: I
surely plan to put the filter into the incoming air (coming into the
room), whatever that piece of tubing is called. Or rather I plan to have
building maintenance put it in there. They will also check for
sufficient airflow. We are also looking into the room pressure right
now. Since this is a lab, I am not sure positive pressure is an option,
due to safety regulations, e.g. regarding genetically engineered
organisms. (S1 now, S2 planned).

I didn't know about the MERV rating, it seems to be not in use in
Europe. When I compare the two scales I get the impression that MERV13
is close to HEPA E10.

By now I also got some feedback from the building maintenance. Their
contacts are of the opinion that the F7/F9 filters we already have
should take care of all the dust in the ventilation ducts and the dust
we do observe is coming from the people entering the room (on clothes
etc).  Does that make sense to you guys? If so, we might want to install
some air cleaner in the room itself, in addition to the filters we have
or will have in the ventilation. I found a cleaner with HEPA H13 filter
and 290m3/h for ~700 Euro
(https://www.trotec24.com/maschinen/luftreinigung/sets-luftreiniger/luftreiniger-tac-750-e-hepa-filter-paket.html).
There are probably other comparable machines which might be better
suited, but so far this is not my area of expertise.

Any opinions? Also on the original question which was which class of
HEPA filter would be recommendable for the ventilation?

Steffen


Am 11.09.2018 um 18:38 schrieb Sam Lord:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> I'm not sure what you mean by "inlet." I don't think you need to filter the air flowing back into the HVAC system for the entire building, because I don't think that will have any noticeable effect on the dustiness in your room. You should install filters on the air source (outlet). I found a HEPA filter that fit the vents in my lab and duct tape it on there:
>
> http://blog.everydayscientist.com/?p=3488
>
> I happened to use a 20x20x1 Synthetic Pleated Air Filter with MERV 13 level filtering. It doesn't impede the airflow significantly, which is important because I want to maintain positive pressure in the room (to keep dust from coming in from the hallway).
>
> I have found that that filter noticeably reduces the dustiness in our scope room!
>
> Sam
>

--
------------------------------------------------------------
Steffen Dietzel, PD Dr. rer. nat
Ludwig-Maximilians-Universität München
Biomedical Center (BMC)
Head of the Core Facility Bioimaging

Großhaderner Straße 9
D-82152 Planegg-Martinsried
Germany

http://www.bioimaging.bmc.med.uni-muenchen.de

[0000001ed7f52e4a-dmarc-request]

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*****

Depending on what you do in the lab, e.g. producing allergens or handling pathogens, you actually also want to filter the exhaust air. Otherwise people might start sneezing or worse when the walk past the building air outlet.

Best wishes

Andreas

Sent from my phone

> On 12 Sep 2018, at 11:41, Steffen Dietzel <[hidden email]> wrote:
>
> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Sam, Craig,
>
> thanks for your comments. Sorry if I got the engineering terms wrong: I surely plan to put the filter into the incoming air (coming into the room), whatever that piece of tubing is called. Or rather I plan to have building maintenance put it in there. They will also check for sufficient airflow. We are also looking into the room pressure right now. Since this is a lab, I am not sure positive pressure is an option, due to safety regulations, e.g. regarding genetically engineered organisms. (S1 now, S2 planned).
>
> I didn't know about the MERV rating, it seems to be not in use in Europe. When I compare the two scales I get the impression that MERV13 is close to HEPA E10.
>
> By now I also got some feedback from the building maintenance. Their contacts are of the opinion that the F7/F9 filters we already have should take care of all the dust in the ventilation ducts and the dust we do observe is coming from the people entering the room (on clothes etc).  Does that make sense to you guys? If so, we might want to install some air cleaner in the room itself, in addition to the filters we have or will have in the ventilation. I found a cleaner with HEPA H13 filter and 290m3/h for ~700 Euro (https://www.trotec24.com/maschinen/luftreinigung/sets-luftreiniger/luftreiniger-tac-750-e-hepa-filter-paket.html). There are probably other comparable machines which might be better suited, but so far this is not my area of expertise.
>
> Any opinions? Also on the original question which was which class of HEPA filter would be recommendable for the ventilation?
>
> Steffen
>
>
>> Am 11.09.2018 um 18:38 schrieb Sam Lord:
>> *****
>> To join, leave or search the confocal microscopy listserv, go to:
>> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
>> Post images on http://www.imgur.com and include the link in your posting.
>> *****
>>
>> I'm not sure what you mean by "inlet." I don't think you need to filter the air flowing back into the HVAC system for the entire building, because I don't think that will have any noticeable effect on the dustiness in your room. You should install filters on the air source (outlet). I found a HEPA filter that fit the vents in my lab and duct tape it on there:
>>
>> http://blog.everydayscientist.com/?p=3488
>>
>> I happened to use a 20x20x1 Synthetic Pleated Air Filter with MERV 13 level filtering. It doesn't impede the airflow significantly, which is important because I want to maintain positive pressure in the room (to keep dust from coming in from the hallway).
>>
>> I have found that that filter noticeably reduces the dustiness in our scope room!
>>
>> Sam
>>
> --
> ------------------------------------------------------------
> Steffen Dietzel, PD Dr. rer. nat
> Ludwig-Maximilians-Universität München
> Biomedical Center (BMC)
> Head of the Core Facility Bioimaging
>
> Großhaderner Straße 9
> D-82152 Planegg-Martinsried
> Germany
>
> http://www.bioimaging.bmc.med.uni-muenchen.de

[samjlord]

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Hi Steffen,

I don't know what the engineering terms are, either. You might be right. I just wanted to make sure we were all talking about the same holes in the ceiling. :)

As far as trusting your facilities folks, I think you need to check on the situation on the ground. If you already have filters immediately before the vents, even it they are not HEPA, that should be sufficient if they are changed every couple months. If the facilities folks are talking about the HEPA filters at the central HVAC unit, I certainly don't think that's enough. Our facilities people kept telling me that the HVAC has HEPA filters, but we always had dust bunnies in our microscope room. After installing a filter right at the vent, things are better. And the vent gets dark gray within a month!

Sam

[Eric Girard]

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Hi all,

This reminds me of a makeshift cleanroom I worked in a few years back.

Il was made using hepa filters and fans embedded in ceiling tiles such as:
https://goo.gl/images/iZEf5C

It could bring a room to positive pressure with clean air, without too much
infrastructure.

Regards,

Eric Girard
Sales Engineering / Ingénierie Ventes

GiGa Concept Inc
Montreal, Quebec, Canada
Cell: 514-826-1181
Tel: [phone]

[hidden email]
www.gigaconcept.com

Meet us at:
Photonics West 2018 Booth 4437
OPIE'18 Yokohama
CLEO 2018 San José


Le mar. 11 sept. 2018 13 h 01, Craig Brideau <[hidden email]> a
écrit :

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Keep in mind much of this is moot if you don't have decent sealing in the
> room. If you have many air gaps (door frames, ceiling tiles, etc) you will
> have ingress of dust regardless of your filters. You can mitigate this by
> having the room at positive pressure, that is more air enters the room than
> is purposely exhausted. This keeps the air constantly blowing OUT any gaps
> and prevents dust ingress. There is a problem with this though, as to
> maintain positive pressure you need sufficient air flow into the room. If
> your filters are very aggressive, they will cause a large pressure drop
> across themselves as the ventilation fans attempt to force clean air into
> the room. In effect, the smaller particle filtering, the higher the
> pressure drop across the filter, and the stronger fans you need to actually
> drive air across them to get the necessary positive pressure into the room.
>
> Craig
>
>
> On Tue, Sep 11, 2018 at 10:38 AM Sam Lord <[hidden email]> wrote:
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > Post images on http://www.imgur.com and include the link in your
> posting.
> > *****
> >
> > I'm not sure what you mean by "inlet." I don't think you need to filter
> > the air flowing back into the HVAC system for the entire building,
> because
> > I don't think that will have any noticeable effect on the dustiness in
> your
> > room. You should install filters on the air source (outlet). I found a
> HEPA
> > filter that fit the vents in my lab and duct tape it on there:
> >
> > http://blog.everydayscientist.com/?p=3488
> >
> > I happened to use a 20x20x1 Synthetic Pleated Air Filter with MERV 13
> > level filtering. It doesn't impede the airflow significantly, which is
> > important because I want to maintain positive pressure in the room (to
> keep
> > dust from coming in from the hallway).
> >
> > I have found that that filter noticeably reduces the dustiness in our
> > scope room!
> >
> > Sam
> >
>

[Craig Brideau]

*****
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http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
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*****

Supply is the air into the room from the main trunk. This will need to be
filtered for dust.
Exhaust is the air leaving the room. This *may* need to be filtered for
biohazards depending on your regulations.
Return can be air drawn from the room that is recirculated into the Supply.
Something like a 70/30 split is common to combine recirculated air to fresh
air from the main duct. This loop should also be filtered to deal with any
dust introduced inside the room from users entering. The pressure drop
induced by the recirculation loop must not cause backflow through the
return ducts.
If you can't have positive pressure, you will need a good door seal or a
great deal of dust will enter from the hallway.

Hope this helps!
Craig

On Wed, Sep 12, 2018 at 11:37 AM Eric Girard <[hidden email]>
wrote:

> *****
> To join, leave or search the confocal microscopy listserv, go to:
> http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> Post images on http://www.imgur.com and include the link in your posting.
> *****
>
> Hi all,
>
> This reminds me of a makeshift cleanroom I worked in a few years back.
>
> Il was made using hepa filters and fans embedded in ceiling tiles such as:
> https://goo.gl/images/iZEf5C
>
> It could bring a room to positive pressure with clean air, without too much
> infrastructure.
>
> Regards,
>
> Eric Girard
> Sales Engineering / Ingénierie Ventes
>
> GiGa Concept Inc
> Montreal, Quebec, Canada
> Cell: 514-826-1181
> Tel: [phone]
>
> [hidden email]
> www.gigaconcept.com
>
> Meet us at:
> Photonics West 2018 Booth 4437
> OPIE'18 Yokohama
> CLEO 2018 San José
>
>
> Le mar. 11 sept. 2018 13 h 01, Craig Brideau <[hidden email]> a
> écrit :
>
> > *****
> > To join, leave or search the confocal microscopy listserv, go to:
> > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > Post images on http://www.imgur.com and include the link in your
> posting.
> > *****
> >
> > Keep in mind much of this is moot if you don't have decent sealing in the
> > room. If you have many air gaps (door frames, ceiling tiles, etc) you
> will
> > have ingress of dust regardless of your filters. You can mitigate this by
> > having the room at positive pressure, that is more air enters the room
> than
> > is purposely exhausted. This keeps the air constantly blowing OUT any
> gaps
> > and prevents dust ingress. There is a problem with this though, as to
> > maintain positive pressure you need sufficient air flow into the room. If
> > your filters are very aggressive, they will cause a large pressure drop
> > across themselves as the ventilation fans attempt to force clean air into
> > the room. In effect, the smaller particle filtering, the higher the
> > pressure drop across the filter, and the stronger fans you need to
> actually
> > drive air across them to get the necessary positive pressure into the
> room.
> >
> > Craig
> >
> >
> > On Tue, Sep 11, 2018 at 10:38 AM Sam Lord <[hidden email]> wrote:
> >
> > > *****
> > > To join, leave or search the confocal microscopy listserv, go to:
> > > http://lists.umn.edu/cgi-bin/wa?A0=confocalmicroscopy
> > > Post images on http://www.imgur.com and include the link in your
> > posting.
> > > *****
> > >
> > > I'm not sure what you mean by "inlet." I don't think you need to filter
> > > the air flowing back into the HVAC system for the entire building,
> > because
> > > I don't think that will have any noticeable effect on the dustiness in
> > your
> > > room. You should install filters on the air source (outlet). I found a
> > HEPA
> > > filter that fit the vents in my lab and duct tape it on there:
> > >
> > > http://blog.everydayscientist.com/?p=3488
> > >
> > > I happened to use a 20x20x1 Synthetic Pleated Air Filter with MERV 13
> > > level filtering. It doesn't impede the airflow significantly, which is
> > > important because I want to maintain positive pressure in the room (to
> > keep
> > > dust from coming in from the hallway).
> > >
> > > I have found that that filter noticeably reduces the dustiness in our
> > > scope room!
> > >
> > > Sam
> > >
> >
>