Fume Hood

This is a forum to share experiences and ideas about holography.
Kiffdino

Fume Hood

Post by Kiffdino »

Hey guys,
want to get back into DCG.
some time ago ive built a laminar flow table out of many many straws. Works like a charm.
Now i want to build a fume hood.
Its cause of the nasty amdi. You think a wooden box with a big HEPA filter inside and a powerful fan behind it will do the trick?
Hepa filter i thaught about H13. Is that enough to trap the amdi particles ?

Or should I abandon the whole makeshift fumehood idea and get myself a mask. ?
Joe Farina

Fume Hood

Post by Joe Farina »

As for the dichromate itself, I don't think a fume hood is necessary. When I use it, I'm just very, very careful not to stir it up, and get dust in the air.

However, ventilation in the lab is essential. I have two powerful air-duct fans in tandem (these fans are used in heating ducts to move warm air) to move air to the outside. When that's in operation, I open a window on the other end of the lab, and keep the window opening covered with a filter, so that dust coming in from outside into the lab is minimized.

Congratulations on the straw-based laminar flow station. I'm an old straw-man myself :wink:
Kiffdino

Fume Hood

Post by Kiffdino »

Thanks Joe for the quick reply.
So you say no hepa filter necessary.
But if i get a powerful fan that sucks the air out of the lab, i could do all the dichromate work in front of the intake.
So all potential dichromate dusts get blown out the window.
Joe Farina

Fume Hood

Post by Joe Farina »

Kiffdino wrote:But if i get a powerful fan that sucks the air out of the lab, i could do all the dichromate work in front of the intake. So all potential dichromate dusts get blown out the window.
I don't recommend doing this. When we're talking about dichromates, the thing to be avoided is particulates floating around in the air which can be inhaled. Anything which stirs up the air can cause problems, such as a fan. Personally, I wouldn't have confidence in any dust-extraction system, in the case of dichromates. Since such small quantities are involved for our purposes, I just exercise great care when transferring the dichromate (preferably in larger crystals to avoid dust) to the container in which it's dissolved. I turn off all my fans, etc., and take a disposable plastic spoon, and very carefully gather up a liitle from the bottle, and place it on a piece of disposable weighing paper on a scale. When the amount is correct, I carefully slide the dicromate from the paper into a container of distilled water, and use this to add to the gelatin. After you re-seal the bottle and get any loose dichromate out of the way, then of course you can turn on your fans full-blast to get the air out of the lab. You can always use a good cartidge-type respirator (not a dust mask) for additional protection, but personally I don't bother with it, I just avoid stirring up the dichromate.
Jeffrey Weil

Fume Hood

Post by Jeffrey Weil »

Joe is mostly correct about this with one exception. If you have a big fan pulling air out of the room it might pull stuff up and move it across the room, and by you and your nose. But, if you have that same fan in a fume hood and you do the work inside the hood, then no. Thats super safe and the way your supposed to do it. Sure, the dust will be pulled up and into the fan but it won't be going by you and your nose. Its going AWAY from you, your at the hoods entrance and the fan is in the back.

When I spray plates black I do it in the hood. If a spray can emitting all that stuff at pressure can't escape the hood, dust can't either. The hood is under lower pressure than the rest of the room, nothing can get out. Put a lighter near the opening of the hood and see if the flame is pulled inside. If it is, your fine.

What I use for a hood like this is a simple plastic box. Lay it on its side so the opening is facing you. Tilt it back a bit so any liquids won't run out and onto your shoes. Now cut a hole in the back on top and put in a piece of duct work. You can get a simple inline duct fan to do the work of pulling it outside.

Make sure where the vent is outside no one is going to be there breathing the stuff.

But, like others have said, you really don't need a hood for dicro. Its pretty heavy stuff in decent sized crystals. Just don't shake it up right before you open it and you'll be fine. If you want the hood, go for it. Its very easy and pretty handy for stuff other than dicro.

Jeff Weil
NorthBeach Holography Inc.
Joe Farina

Fume Hood

Post by Joe Farina »

Jeffrey Weil wrote:Joe is mostly correct about this with one exception. If you have a big fan pulling air out of the room it might pull stuff up and move it across the room, and by you and your nose. But, if you have that same fan in a fume hood and you do the work inside the hood, then no. Thats super safe and the way your supposed to do it. Sure, the dust will be pulled up and into the fan but it won't be going by you and your nose. Its going AWAY from you, your at the hoods entrance and the fan is in the back.
I agree, but only for a properly-functioning commercial fume hood or equivalent. Since Kiffdino seems to be a do-it-yourself kind of guy, I would still discourage using a homemade dust-extraction system. Things could go wrong for the inexperienced, and airborne dichromates are a pretty serious matter.
Kiffdino

Fume Hood

Post by Kiffdino »

ok im convinced. No DIY fume hood.
I just get the mask for measuering the stuff.
Thieu

Fume Hood

Post by Thieu »

Joe Farina wrote: I turn off all my fans, etc., and take a disposable plastic spoon, and very carefully gather up a liitle from the bottle, and place it on a piece of disposable weighing paper on a scale. When the amount is correct, I carefully slide the dicromate from the paper into a container of distilled water, and use this to add to the gelatin.
I use the same method. If you're in an environment with very dry air I would recommend to use a metal spoon though and (electrically) ground yourself to the sink or another grounding point. Otherwise the build up of static electricity in some plastic spoons can repel substantial amounts of powder particles into the air.
Thieu

Fume Hood

Post by Thieu »

Btw, if you want to check how clean you are working it can be insightful to work with a very deeply colored compound like potassium permanganate or a well soluble strong dye once as a test. You'll be surprised to see the unthought-of places where it ends up.
Jeffrey Weil

Fume Hood

Post by Jeffrey Weil »

Here's another safe way to do things. Dicro in water will last forever. Mix up some outside, stay upwind, and use your mask. Mix up a quart or whatever will last a long time. That way instead of mixing ten times, your only mixing once. And your outside so no residue will end up in the lab.
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