Sciencemadness Discussion Board

Insulate fume hood?

antimon - 12-10-2015 at 03:47

Hi, i just finished making the wood frame of my fume hood, in my storage shed. Now i am just going to put up one of the side walls, and put in some tiles i was planning.
Its just one thing that is bothering me. I am distilling some water in there now, and i have to put the hotplate on 200 degrees to get it dripping.
The temperature inside the shed now is around 10 degrees C, same as outside.
It is an uninsulated shed, so i was thinking about insulating it, but i have a pretty tight budget.
I was wondering if you guys think that it would be a good idea to insulate the fume hood first before doing the shed in the future?

The hood will have a plexi sash on the front side ofcourse, so the front wont be insulated.
Will this be meaningless due to that the sash isnt insulated, and/or the fan will draw cold air inside and it wont make a difference as long as the fan is running, or do you think i should i go for it?

Ps. If you need to see pictures, then just ask. :)

Thanks in advance.

xfusion44 - 12-10-2015 at 03:57

What about styrofoam? Of course the styrofoam would be put on the outside, due to reactions and heat inside the fume hood :)

Little_Ghost_again - 12-10-2015 at 04:54

second skin and vermiculite its inert. and wont be effected by heat.
Or the rock wool stuff is pretty cheap

[Edited on 12-10-2015 by Little_Ghost_again]

Sulaiman - 12-10-2015 at 04:59

My first choice would be to insulate the shed,
warmer in winter to prevent freezing of liquids
and cooler in summer to reduce evaporation of solvents etc.,
not just for your experiments/chemicals, for personal comfort as well.

Magpie - 12-10-2015 at 08:24

If your blower is adequate it will be pulling in so much cold air that the hood insulation will be irrelevant. Insulating the shed won't help either.

antimon - 12-10-2015 at 14:22

I am leaning towards insulating the whole shed, if the material is in my price range. Otherwise, i will go with doing just the hood for now.

Btw, the fan i am planning on using draw about 350-400 cfm. Is that too weak?

Thanks for taking your time guys. :)

aga - 12-10-2015 at 14:29

Biggest fan you can afford is best.

Also affects how well it can send the nasty stuff over any distance of ducting.

Magpie - 12-10-2015 at 14:55

That's just right for a 4' wide hood and ducting diameter ≥8". If it is too strong it will blow out your bunsen burner.

antimon - 19-10-2015 at 03:13

I think off the top of my head that the hood is about 70x70 cm, and about 80 cm high.

Magpie - 19-10-2015 at 09:48

your hood face area = {(70cm)(80cm)/[(2.54cm/in)(2.54cm/in)]}/(144in^2/ft^2) = 6.0 ft^2

V = Q/A = 400 cfm/[(60s/min)(6.0 ft^2)] = 1.1 ft/s

This is a perfect face velocity with the sash completely open. But you need the sash down to protect you. When you close off the sash the face velocity is going to increase. You may have to cut back on the airflow. Then again if your duct size is much less than 8" diameter the airflow will be restricted anyway. Rough ducting with turns will also restrict airflow.

[Edited on 19-10-2015 by Magpie]