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converting a machine into a spray booth

updated tue 16 aug 05

 

Merry Monk Design on tue 9 aug 05


I've been avidly reading the postings about spray
booths. Thanks to all the very experienced potters
who have shared.

I dumpster dove a really sweet horizontal laminar flow
booth and am thinking about converting it into a spray
booth. It is a Baker EG3252
( image at http://bakerco.com/products/edgegard/ ) and
was used at a local university's biology lab. The air
flow is the reverse of what I need for a spray
booth--it goes in the bottom register and out the top
bench area (to provide clean air for an experiment).
The existing motor is not reversible, although it
pulls 1000 cfm into the bottom register. The air
coming out the top is much slower, due to the current
hepa filter, which I would change to a furnace filter
or something like that. Do
you have any suggestions on how I can convert this to
a spray booth?

I've been debating whether to just sell the thing on
eBay and buy a commercial spray booth or convert the
Baker to what I need. A local scientific equitment
co was
going to buy it but then never confirmed. They
offered $500 for it, but I should get a lot more on
eBay, but that takes some
time and I really need to set up...yesterday. But
perhaps that would be easier than taking the time to
convert this machine? I am fairly handy but haven't
done this type of conversion before.

Any suggestions will be greatly appreciated.

Amy Sanford
amy@merrymonkdesign.com

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Linda Ferzoco on tue 9 aug 05


If that laminar flow biohazard hood still has the HEPA filter in it, please
treat it as a potential biohazard itself. That hood and filter removed all
airborne particulates and organisms from the air for years. You have no way
to know what organisms may have been trapped on the filter.

Frankly, it should not have been disposed of in that manner and with the
filter intact. There are rules about decommissioning these things and the
filters are supposed to be sterilized before removal, but crazier things
have happened.

Sorry to be alarmist,
Linda
California

Snail Scott on wed 10 aug 05


At 08:15 PM 8/9/2005 -0400, you wrote:
>If that laminar flow biohazard hood still has the HEPA filter in it, please
>treat it as a potential biohazard itself. That hood and filter removed all
>airborne particulates and organisms from the air for years. You have no way
>to know what organisms may have been trapped on the filter...


I thought this was a clean-air supply hood.
Wouldn't the stuff in the filter be the same
stuff you'd be breathing in the air anyway?

-Snail

Linda Ferzoco on thu 11 aug 05


On Wed, 10 Aug 2005 08:54:45 -0500, Snail Scott wrote:

>At 08:15 PM 8/9/2005 -0400, you wrote:>
>I thought this was a clean-air supply hood.
>Wouldn't the stuff in the filter be the same
>stuff you'd be breathing in the air anyway?
>
> -Snail
>

It sounded to me like a laminar flow hood used in laboratories. We'll have
to wait for the original poster to clarify that.

I don't know about HVAC clean air supply hoods, although I'm aware that
there are HEPA filters in the HVAC supply for certain room applications,
called clean rooms.

They used to be used for long, infection-prone surgeries until studies
showed that the biggest source of contamination in an OR is the OR staff.
Human beings shed kajillions of particulates per unit time and those
particulates carry organisms as well as inert debris, you know, skin,
dandruff, etc. That's why the OR staff is now suited up in sterile
disposable clothing; protects the patient better.
Simlar deal in the silicon chip industry, which is where the HEPA filters
were first used.

Linda
CA

On Wed, 10 Aug 2005 08:54:45 -0500, Snail Scott wrote:

>At 08:15 PM 8/9/2005 -0400, you wrote:
>>If that laminar flow biohazard hood still has the HEPA filter in it, please
>>treat it as a potential biohazard itself. That hood and filter removed all
>>airborne particulates and organisms from the air for years. You have no way
>>to know what organisms may have been trapped on the filter...
>
>
>I thought this was a clean-air supply hood.
>Wouldn't the stuff in the filter be the same
>stuff you'd be breathing in the air anyway?
>
> -Snail
>
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Merry Monk Design on thu 11 aug 05


Yes, Snail Scott, you're correct. The regular air
from the room gets sucked into the filters and blows
out gently onto the work bench area, providing a clean
air environment for whatever experiment you're working
on. Fred P says that these laminar flows are good to
help orchids establish, they need a very clean
environment.

I still don't know what to do. Converting it seems
like a pain but the $$ I'd get for it isn't enough to
buy what I need.

Amy Sanford
amy@merrymonkdesign.com

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Linda Ferzoco on sat 13 aug 05


I'm sorry to be so pesty, but yes, of course the laminar flow hood takes
room air and cleans it and washes the bench area with cleaned air; that's
what it was designed to do.

However, these hoods with their HEPA filters, which I spent 20 years of my
life working with directly and another 10 or so working with peripherally,
trap whatever organisms the laboratory might have been working with on the
filter. For that reason, they are certified to be operating in such a way
that there are no leaks of contaminated air onto the bench surface. In
every situation in which I worked, if one of these hoods was moved at all,
it had to be recertified as air-tight downstream of the filter.

Why? Because if it weren't air-tight, then it was possible that trapped and
potentially hazardous organisms could enter the bench area, endangering the
experiment and especially, the operator. Your hood, if it still has the
filter in place, cannot possibly be air-tight.

If the filter were to be replaced because it was starting to become clogged,
said filter had to be decontaminated in place using very toxic materials and
then bagged and disposed of in hazardous waste disposal areas.

I don't know what kind of facility this hood came from. If it came from a
lab doing plant research, well then the list of possible human pathogens
would be lower than if it had come from a hospital or biology lab.

The final reason that you might not want to use this hood: that HEPA filter
will clog with spray dust so fast that you will regret the time you put into
it. They were designed to be used in relatively clean rooms, not dusty
environments.

I'm concerned for your health and that's why I'm being such a pest. This is
the last I'll say about it.

Linda
California

Merry Monk Design on mon 15 aug 05


Thanks for your info, Linda, and you're not being a pest. I was going to remove the HEPA filter anyway and replace it with a furnace filter. If I wash the unit, inside and out with ammonia and remove the filter, do you think that might be enough? Perhaps I should just sell it. It was SUCH a find, though.

Amy Sanford
amy@merrymonkdesign.com

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