Laminar Flow Hood/Bench specifications

JohnFP · Post by **JohnFP** » Tue May 04, 2004 1:03 pm

Would anyone happen to know who many cubic feet per minute of air need to go into a Laminar Flow Hood/Bench with an opening (let's say) 3 feet by 2 feet (6 square feet) in order to keep particles from entering in the hood area.

Or easier yet, does anyone have a Laminar Flow Hood/Bench that could give me what their SCFM are for the positive pressure, the size of their enclosure and the size of their opening?

Many thanks in advance,
John

Colin Kaminski · Post by **Colin Kaminski** » Tue May 04, 2004 1:40 pm

I'll look up mine this afternoon.

JohnFP · Post by **JohnFP** » Tue May 04, 2004 1:57 pm

BTW, you never responded to my last e-mail with boot.ini.

JohnFP · Post by **JohnFP** » Tue May 04, 2004 1:58 pm

Did you buy yours or make it? Any other "you should knows" on building one?

JohnFP · Post by **JohnFP** » Tue May 04, 2004 2:19 pm

Also, does yours have the double - negative thru regular filter to a chamber over the bench then postive thru a heppa to the working area? Is that a required configuration?

Colin Kaminski · Post by **Colin Kaminski** » Tue May 04, 2004 3:35 pm

Mine is a 23 x 59" work surface. The back wall is a 59 x 34 1/2" HEPA filter. It is important to make sure the Filter goes all the way to the edges of the enclosure. There are Plexiglas sides but the front is open. Beneath the table there is a squirrel cage motor and a prefilter on the inlet. The prefilter looks like a furnace filter. There is a Gage to measure the pressure behind the HEPA filter so you can decide when it is time to replace it. Above the work space is flush mounted fluorescent lighting. It was manufactured by Laminaire.

The motor and squirrel cage have likely been replaced. The one installed is 11" in dia and 10" long (the fan blade itself"). The motor is a three speed 1/2" HP capacitor start but I don't know what speed it is running at, as I only have one speed wired.

I use it to handle yeast and test it often for biological contamination. It is very good at keeping airborne yeast and bacteria out. Plates left for one minute with the fan off will grow colonies. Plates left for an hour with the fan on show no growth.

Colin Kaminski · Post by **Colin Kaminski** » Tue May 04, 2004 3:36 pm

I finally was ablte to make it let me log on but when I would it would log me right back off. I could not reply because it took out the main drive I was copying from. Yesterday I finally just built a new system from scratch. I hate Microsoft.

jean · Post by **jean** » Tue May 04, 2004 4:24 pm

I can't give responses to your request but take a look here :
http://www.omnisterra.com/botany/cp/slides/tc/hood.htm

JohnFP · Post by **JohnFP** » Wed May 05, 2004 6:20 am

Well, time to buy some supplies and take the next step in film production.

I hope to shoot those plates I made Saturday this evening!

JohnFP · Post by **JohnFP** » Wed May 05, 2004 8:35 am

Thank you Colin!

I think I may make mine 4 foot wide, 2 foot deep and 4 foot high. I will place a piece of 2' by 4' Plexiglas over the top front to leave an opening of 2' by 4'. Behind that top cover will be a chamber of the dimensions of the working surface by 18 inches high. Separating the chamber and working area will be a 2' by 4' heppa filter if I can find them that big. If not I may have to reduce the size of the opening for the heppa. Inside the chamber and mounted over a hole in the top of the chamber will be a huge fan that I have that was designed to cool a DPSS laser. It is about 9 inches in diameter. Then above the hole on the outside will be a regular filter of about 1 foot by 1 foot covering the hole.

This drawing is not to scale but represent the basic idea. If the fan is not strong enough I will have to add additional fans in the top chamber which should be accessable with the heppa removed. But the fan I have stokes.

What do you think?