In the Laminar flow hood there's a Germicidal lamp do you leave it on while
flasking or turn it off?

Also what CFM airflow do you set the adjustment at?

Thanks very much
Dusty

Dusty asked about UV lights and airflow in HEPA filters.

I have never used the UV light in a laminar workstation. In fact,
there is no strongly compelling reason to use them in the first place; the
only occasion where one might use it is if massive contamination was
suspected (even then, one should find the source, rather than treat the
whole darned thing) in the filter element or elsewhere in the hood, or if
the filter has been moved or in storage for a long period of time. Even
then, leaving the fan on for 24 hours should blow out virtually all the
gunk on the downstream side of the element. A quick wipedown with 70%
ethanol is good enough for the working surfaces.

Using these principles at work, I suffer the least contamination
of anyone who works in the plant tissue culture group. I can't remember
the last time I had contamination in a tissue culture, in fact.

As for airflow- total CFMs won't do anything for you. What is
more important is the face velocity, which should be 90+ linear feet per
minute. You can get this from CFMs by determining the size of your
working face, and dividing CFMs by that number. Of course, it's much more
practical to measure the working face velocity, since you never know how
many CFMs your fan is putting out- unless you trust the label. And if you
trust the label, then why are you having to determine how much air you're
moving?

In reality, much lower velocities are fine, provided your
technique is good, and nobody walks behind you while you're working at the
filter.

The e-mail address in the header doesn't work. Sorry.

-AJHicks
The Orchid Seedbank
Chandler, AZ

(Aaron Hicks) wrote in message ...
Dusty asked about UV lights and airflow in HEPA filters.

I have never used the UV light in a laminar workstation. In fact,
there is no strongly compelling reason to use them in the first place; the
only occasion where one might use it is if massive contamination was
suspected (even then, one should find the source, rather than treat the
whole darned thing) in the filter element or elsewhere in the hood, or if
the filter has been moved or in storage for a long period of time. Even
then, leaving the fan on for 24 hours should blow out virtually all the
gunk on the downstream side of the element. A quick wipedown with 70%
ethanol is good enough for the working surfaces.

Using these principles at work, I suffer the least contamination
of anyone who works in the plant tissue culture group. I can't remember
the last time I had contamination in a tissue culture, in fact.

As for airflow- total CFMs won't do anything for you. What is
more important is the face velocity, which should be 90+ linear feet per
minute. You can get this from CFMs by determining the size of your
working face, and dividing CFMs by that number. Of course, it's much more
practical to measure the working face velocity, since you never know how
many CFMs your fan is putting out- unless you trust the label. And if you
trust the label, then why are you having to determine how much air you're
moving?

In reality, much lower velocities are fine, provided your
technique is good, and nobody walks behind you while you're working at the
filter.

The e-mail address in the header doesn't work. Sorry.

-AJHicks
The Orchid Seedbank
Chandler, AZ

I would say ditto on the uv light--they are dangerous. If you can see
the light when it is on---don't ever turn it on--better yet take the
bulb out!!!! I dont have uv light in my hood. I suspect that those
hoods that do have it, have it to keep the hood contaminant free when
not in use--I just leave mine on. As for airflow--mine is equiped with
a mag. gauge that measures "stack pressure" I only use it to know when
the filter or prefilter needs changed I set it at .75 which is
supposed to represent 3/4". Doubt if this is much help. AJ's seems to
be right on the money. Bill

(Aaron Hicks) wrote in message ...
Dusty asked about UV lights and airflow in HEPA filters.

I have never used the UV light in a laminar workstation. In fact,
there is no strongly compelling reason to use them in the first place; the
only occasion where one might use it is if massive contamination was
suspected (even then, one should find the source, rather than treat the
whole darned thing) in the filter element or elsewhere in the hood, or if
the filter has been moved or in storage for a long period of time. Even
then, leaving the fan on for 24 hours should blow out virtually all the
gunk on the downstream side of the element. A quick wipedown with 70%
ethanol is good enough for the working surfaces.

Using these principles at work, I suffer the least contamination
of anyone who works in the plant tissue culture group. I can't remember
the last time I had contamination in a tissue culture, in fact.

As for airflow- total CFMs won't do anything for you. What is
more important is the face velocity, which should be 90+ linear feet per
minute. You can get this from CFMs by determining the size of your
working face, and dividing CFMs by that number. Of course, it's much more
practical to measure the working face velocity, since you never know how
many CFMs your fan is putting out- unless you trust the label. And if you
trust the label, then why are you having to determine how much air you're
moving?

In reality, much lower velocities are fine, provided your
technique is good, and nobody walks behind you while you're working at the
filter.

The e-mail address in the header doesn't work. Sorry.

-AJHicks
The Orchid Seedbank
Chandler, AZ

I would say ditto on the uv light--they are dangerous. If you can see
the light when it is on---don't ever turn it on--better yet take the
bulb out!!!! I don't have uv light in my hood. I suspect that those
hoods that do have it, have it to keep the hood contaminant free when
not in use--I just leave mine on. As for airflow--mine is equiped with
a mag. gauge that measures "stack pressure" I only use it to know when
the filter or prefilter needs changed I set it at .75 which is
supposed to represent 3/4". Doubt if this is much help. AJ's seems to
be right on the money. Bill

Dusty,

Don't sneeze straight on into the hood... and tell that person behind you
(as Aaron foresaw) not to sneeze toward the hood either. That's my rule
when working in my 6 year old homemade hood (with no fancy smancy UV light).

Mick
HBI, Producers of Fine Orchids in Flask
www.OrchidFlask.com

(Aaron Hicks) wrote in
:

Dusty asked about UV lights and airflow in HEPA filters.

I have never used the UV light in a laminar workstation. In fact,
there is no strongly compelling reason to use them in the first place;
the only occasion where one might use it is if massive contamination
was suspected (even then, one should find the source, rather than
treat the whole darned thing) in the filter element or elsewhere in
the hood, or if the filter has been moved or in storage for a long
period of time. Even then, leaving the fan on for 24 hours should blow
out virtually all the gunk on the downstream side of the element. A
quick wipedown with 70% ethanol is good enough for the working
surfaces.

Using these principles at work, I suffer the least contamination
of anyone who works in the plant tissue culture group. I can't
remember the last time I had contamination in a tissue culture, in
fact.

As for airflow- total CFMs won't do anything for you. What is
more important is the face velocity, which should be 90+ linear feet
per minute. You can get this from CFMs by determining the size of your
working face, and dividing CFMs by that number. Of course, it's much
more practical to measure the working face velocity, since you never
know how many CFMs your fan is putting out- unless you trust the
label. And if you trust the label, then why are you having to
determine how much air you're moving?

In reality, much lower velocities are fine, provided your
technique is good, and nobody walks behind you while you're working at
the filter.

The e-mail address in the header doesn't work. Sorry.

-AJHicks
The Orchid Seedbank
Chandler, AZ



Thanks for the information Aaron.
The reason I asked for CFM is because the only instrument I have for
measuring air flow reads in CFM. Your formula will be helpful.
Again thanks very much.
Dusty