Laminar Flow Hood - basic question (Aug/31/2005 )
When disinfecting a laminar flow hood with UV light do you have the blower on or not? Thanks.
we usaually don't have it on, because there is a cover to seal the hood of UV from our eyes! 
Nick
Okay... lets try for a serious answer (like I am not guilty of that)
With the glass screen down, turn on UV light. Leave that way for about 30 min.
Turn off UV light, turn on fluorescent light and turn on fan. Open glass screen.
Alcohol wipe the metal surface... Wait until it is dry... it is the rapidly dehydrating activity of alcohol that kills bactera.
Wipe of hands and arms with alcohol.. wait for them to dry.
Begin cell culture.
The point of the fan is to provided laminar air flow in front of the glass screen so that any nasty bugs that try to float in while you are working get sucked down and out of the way.
Thanks for the info!
Cleo
Hi,
Further to the above answers,
I'm curious about if I have to leave the UV lamp opened when not in use?
I've heard that it would be sufficient just to have the UV light opened for 30min before and after use.
is it true? why?
Very appreciate for your reply...
Further to the above answers,
I'm curious about if I have to leave the UV lamp opened when not in use?
I've heard that it would be sufficient just to have the UV light opened for 30min before and after use.
is it true? why?
Very appreciate for your reply...
Some people leave the UV on when not in use; while others leave the UV on before and after use for at least 30min. I think 30 min is enough to kill the bacteria in the hood.
It is mainly the habit. I normally leave UV on when not in use because I have no patience in waiting for 30 min!!
Some studies have demonstrated that UV may not actually kill the bacteria. I don't know whether it is true or not
. I hope this may help.
This old chesnut again....... the leading manufacturers of Laminar flow and Class II cabinets DO NOT recommend UV as a method of keeping cabinets and hoods clean. We recently bought 26 class II cabinets and the manufacturers, Heto Holten(Thermo electron ltd) no longer have UV fitted as standard. In my 30 years of tissue culture we have never used UV in any area I have worked in. The guys in the 1970's who taught me cell culture were convinced that it encouraged bad practice. If when you have finished your work you decontaminate the hood with Virkon and 70% IMS this is sufficient.
How many people using UV check their bulbs are still actively working ? and change them on a regular basis ?
I never use UV (you have to count how many hours you use it and change it regularly, i.e., UV lamps are no more efficient in the majority of the labs.)
I clean with a special detergent and with EtOH 70°. My hood is perfectly clean :
(once some tissue sample felt between the two culture plates, and touched the hood surface. 
I put it back in the culture plate, no contamination 
)
Dear all,
Thank all of you for these nice answers.
Now I learned I shouldn't count too much on UV light only and feel more confident with my daily practice.
^___^
Hi Rhombus (and Missele)
We are long time users of UV (on all night in our Class II hoods and whenever they are not in use) but I must admit we only ever change the globes when they blow. You both suggest that the lamps need to be replaced regularly (do you have a maximum hours recommendation?).
Also, just out of curiosity (and in the interests of objective science) do you know the minimum UV output from the globes that is supposedly required to maintain sterility? I have a UV meter so I'll check the output of our (generally very old!) lamps - and will report back the results.
Many thanks.