Sorry about the delay in answering, been off at a flower show.


The filter in the JA-RO-CA Enterprises Flasking Hood is about 1-foot
by 2-feet.

yep, my hood uses as 1 by 1 filter.


I am sure it meets no
standards, but my contamination rate is very low.

That's what counts.

If that is what counts and you will only be making a limited number of
flasks, a glove box is a good option. Remember 10 bottles means something
like 300 plants and to grow out that many will requires some space.


When selecting a blower it is critical to get one designed to operate at
the
high static pressure required to get the air through the filter. Looking
at
just the CFM is not enough.

How does one do that? The JA-RO-CA Enterprises Flasking Hood uses two
centrifugal blowers each mounted directly on an end of the motor
shaft. The motor is rated for continuous duty, but that doesn't
really address the issue of aerodynamic load on it.

I called the filter manufacture and asked what a typical flow through the
filter was and what the static pressure was at that flow rate. I then went
to the Grainger catalog and found a blower that meet the requirement. I
found this flow was too much (I flame tools) so I added a motor rheostat and
only use it at full speed when I first start the hood.

How much flow that is actually need is tied to how big the openings are for
your hands. The bigger the openning, the bigger the required flow is.

As you use your filter, it will slowly get clogged. As it gets clogged,
static pressure will increase and your blower must work harder. I blew my
first blower by working it too hard with a clogged filter. My hood now has
a static pressure gauge. At full speed a new filter has a static pressure
of .4 inches and is replaced before 1 inch.

Best deals I have seen on hoods are at state surplus auctions. Here in
VA,
I see nice hoods (the open front workstation type) come up every couple
of
months. They sell for very cheap money.

That sounds encouraging. I'm tempted to ask if you'd be willing to
act as my agent in procuring one for me. But the cost of
transcendental shipment might not make such an arrangement practical.

My cost would be greater then the filter and the shipping combined. All I
was saying is that there are a lot of these things floating around. Find
out how local universities and public heath offices dispose of surplus
equipment, I bet in time there is a hood at the end of the search.

What's your feeling about the possibility of success in purchasing a
small HEPA room air filter unit, and adapting a hand-constructed
plexiglass hood to it for use in flasking small batches? They are
available for under $100 on eBay.

Beats me. The filters look very different, but the ads say they produce
similar results. The air intake will have to be outside of the box which
may take some doing. The way I flask, the unit would have to be able to
stand up to bleach which is unlikely, but maybe you could find a way around
that.

Pat