DIY Lab Fume Hood

I have always tried to be as safe as possible, and to be honest, the more dangerous (ether, methanol, pentane, hexane) solvents have scared me, mainly due to vapor fears.

So, I am going to build a DIY lab fume hood and would love some feedback. Here is the scale of what I am trying to do:

https://www.grainger.com/product/ICI-Fume-Hood-45MK56

This has a lot of good details:

https://www.baylor.edu/ehs/index.php?id=92585

I am just getting started and considering all design options at this point. Basic idea is this:

Welded tube steel frame
Stainless steel sheet for interior walls
Minimal control panel with light, fan on/off, fan speed
Simple tubing access/connections/valves for vacuum, chiller & nitrogen

I will be posting more details as I progress, but for now I have a few questions about exhausting to start:

For a myriad of reasons, including the safety of others, I would like to minimize the output of fumes to as little as possible. I read that activated carbon seemed to be the preferred method of capturing these vapors. How effective would a Phresh inline filter (https://growershouse.com/phresh-inline-filter-6in) be at removing ether, methanol, pentane and hexane? How long (much vapor in ml) would it last for? Is there a more efficient method of vapor removal?

I already have a Hyper Fan Digital Mixed Flow 8 inch - 710 CFM with speed controller (https://growershouse.com/hyper-fan-8in-710-cfm) that I would like to use, as the speed controller is very precise and easy to integrate into hood. If I had one or more inline carbon filter between hood and fan, do you think this fan would be safe for those solvents above?

Hyper Fans are designed and built with many features that increase longevity, reduce operating costs, and drastically lower heat output.

With a Next Generation "Multi Phase" motor that uses up to half the power of traditional EC or DC motors. The internal large sized, self lubricating ball bearings ensure smoother operation, less heat friction and increased lifespan, extremely quiet, long lasting and very reliable.

Hyper Fan combines Laminar Blade Design and Stator Technology inspired by the modern jet engine, to reduce noise, increase airflow and create the highest static pressure performance of any fan in it's class.

The included speed controller can adjust fan speed from 30% to 100%. It is detachable from the fan and independent from the power cord.

Hyper Fans are in a class of their own with innovative features, benefits, value and backed with a 5 year warranty... these vibration-free fans are truly one of best on the market.

Uses about half the power as traditional fans.
Lightweight aluminum housing is one-third the weight of comparable steel bodied fans.
Compact and easy to install.
Universal mounting positions – can be mounted in any position allowing maximum flexibility during installation.
Heavy-duty 6/8/10 mm bearings, versus commonly used 4 mm bearings, ensure smoother operation and increased longevity of the fan.

Click to expand...

Just to be clear, inline carbon filter(s) would be directly attached to hood vent and fan would pull air through system and then vent outside.

Appreciate any insights! Should be a fun project...

WFF

check out the patents you can find something useful

https://patents.google.com/?q=fume+hood&oq=fume+hood

A schematic of how I built our's is attached. The front door was plexiglass framed in 3/4 plywood.

The air is exhausted through a rear plenum, with a slot at the bottom and top, and some intermediate ones.

Exhaust slot velocity is 1000 surface feet.

Makeup comes in the side and is distributed via a bottom air knife. That sweeps the heavier than air vapors into the lower slot and the upper ones pick up any lighter than air or mixed air.

Carbon filters are for smell and won't last long in an active exhaust hood. Better a tall stack with a injector cap to mix the exhaust thoroughly.

Check out Industrial Ventilation, A Manual of Recommended Practice, for design criteria, cfm and velocities.

check out what mushroom growers use, diy stuff easy to make and 800+cfm with a rheostat controller and a hepa and you are set up to go or buy one for $5500.00
all sorts of great info on mycotopia back in the day, made these back in the 90's, still have my setup for our work, nice thing now is hepa's are way cheap, used to cost a fortune.

fume hood and laminal flow hood not the same.. one for sterile workplace to avoid contaminations other to save you from chemicals burn or harm your lungs..

Would simply using a kitchen exhaust fan like they put over stoves work?

We built a small paint booth (about 3'x3'x3') out of sheet metal and then used one of these to vent the entire booth.

Just for painting small parts. Had a little microwave platter to spin the part while you spray painted it.

I was thinking about the same thing for my lab. Does my idea present a fire/explosion hazard?

Thanks and good luck on yours.

It would make sense to simply put a table in a 4x4 tent with the fan intake along a top rail and vented out, and fresh air coming in from the opposite bottom. Or you could put the carbon filter on your face.

Ringodoggie said:

Would simply using a kitchen exhaust fan like they put over stoves work?

We built a small paint booth (about 3'x3'x3') out of sheet metal and then used one of these to vent the entire booth.

Just for painting small parts. Had a little microwave platter to spin the part while you spray painted it.

I was thinking about the same thing for my lab. Does my idea present a fire/explosion hazard?

Thanks and good luck on yours.

Click to expand...

Is your kitchen exhaust fan motor NEMA 7, Class I, Div I?

How much static pressure will it pull and how many cfm?

Industrial Ventilation recommends 100 to 200 surface feet capture velocity, and 1000 cfm slot velocity.

A 3' X 3' X 3' booth would require 900 CFM minimum, at what ever static pressure you are running at, and the fan needs to be explosion and spark proof.

Ours was TOMANDME AOK, Classy as hell, Div I (didn't smell shit).

LMAO

Ours worked better than spraying in the basement without it. LOL

My biggest concern today would be the explosion hazzard.

I like the idea of the table in the tent.

Cannabis Alchemy by D Gold

Chapter Three
THC Acetate

THC acetate has twice the potency of THC. On the Adams scale THC 7.3, while its acetate = 14.6. Furthermore, there is a 25% increase in weight after adding the acetate structure. The effect of the acetate is more spiritual and psychedelic than that of the ordinary product. The most unique property of this material is that there is a delay of about thirty minutes before its effects are felt.

Building a safety box in which to convert high-rotating THC to its acetate

Because this conversion utilizes a very dangerous chemical, acetic anhydride, a safety box is constructed in which to perform this operation. This places a shield between the chemist and the apparatus, and the operation takes place in a separate atmosphere. The fumes from heated acetic anhydride are very flammable and poisonous. Inhalation of the fumes is a most unpleasant and dangerous experience, so a glove box protects the operator from any contact with the fumes. Acetic anhydride is so difficult to handle safely that it is a necessity to use standard laboratory equipment and procedure. The reaction is monitored and controlled from outside the box by observing the equipment through a safety-glass window and manipulating the apparatus with long gloves sealed to the shield. The box is equipped with an adequate exhaust fan with a sparkless electric motor to quickly evacuate any fumes that arise while transferring solutions or from a spill or other mishap. A fire extinguisher is mounted inside the box. In case of fire or explosion, the chemist is protected by the thick front piece of the box and by its structural design. The box can also be used for any other chemical operation requiring an artificial atmosphere to avert fire or explosion.

An artificial atmosphere is created by replacing the air in the sealed box with anhydrous nitrogen gas. This makes flame or combustion (oxidation in general) impossible. The nitrogen is introduced into the chamber through an opening in one side, near the top of the box. The displaced air is removed through a valve near the bottom of the opposite end. Success here is determined by attempting to strike a match inside the box. When oxygen has been removed, this becomes impossible. The exhaust fan is then used only when it becomes necessary to evacuate the atmosphere in the box.

The three stations are utilized as follows: The equipment and bottled chemicals are put into the right-hand side of the box by lifting the hinged side piece. The apparatus is prepared at this station and operated in the middle at station two. The bottles are opened at station one, using the gloves, from the outside of the box after the side flap is closed and the atmosphere has been replaced with anhydrous nitrogen gas. The operator need never be exposed to the dangerous chemicals except within the controlled atmosphere of the box.

Diagrams showing details of construction are shown below:
(Figures 3.1, 3.2, & 3.3 - see the attachments)

The side walls of the box are made of thin plywood and hinged at the top. This serves two purposes: access to the box is available from both ends, and in case of explosion, the force would be expended through the side panels, while the thick, reinforced front boards protect the chemist.

https://calgarycmmc.com/E-books/E Books A-B-C/Cannabis Alchemy - D. Gold.pdf

The above link to the book works, use the trick in my ICMAG Signature to open it.



The fan doesn't need to be explosion proof to be effective, the rating only means in case of an external explosion the fan motor is protected from the flames reaching the windings, and hopefully it will continue to function.


Attic gable mount exhaust fans are an inexpensive high CFM choice.

WHIPEDMEAT said:

check out the patents you can find something useful

https://patents.google.com/?q=fume+hood&oq=fume+hood

Click to expand...

Nice. Lots of red meat to chew on.

Gray Wolf said:

A schematic of how I built our's is attached. The front door was plexiglass framed in 3/4 plywood.

The air is exhausted through a rear plenum, with a slot at the bottom and top, and some intermediate ones.

Exhaust slot velocity is 1000 surface feet.

Makeup comes in the side and is distributed via a bottom air knife. That sweeps the heavier than air vapors into the lower slot and the upper ones pick up any lighter than air or mixed air.

Click to expand...

Most helpful. Do you have a photo of the completed box and air knife portion? Is it basically a large lip in front?

Gray Wolf said:

Carbon filters are for smell and won't last long in an active exhaust hood. Better a tall stack with a injector cap to mix the exhaust thoroughly.

Check out Industrial Ventilation, A Manual of Recommended Practice, for design criteria, cfm and velocities.

Click to expand...

Will check that out. I have to be as stealthy as possible, so a tall stack is probably out. I was thinking about creating a ducting system with two paths right off the hood using wye branches. I would only use carbon for the most hazardous solvents and sensitive times of the day, with the damper open for the rest. Something like this maybe:



This seemed to have some good info about filters - https://www.labconco.com/articles/considering-a-ductless-hood

G.O. Joe said:

It would make sense to simply put a table in a 4x4 tent with the fan intake along a top rail and vented out, and fresh air coming in from the opposite bottom. Or you could put the carbon filter on your face.

Click to expand...

I am picking up some used restaurant stainless prep tables and trying make a more proper lab environment. What are your thoughts on solvent retention by active carbon with say ether or pentane? Do these solvents revert to liquid within carbon pores? Will the solvent naturally try to escape from the carbon?

While the micro-pores are crucial to solvent retention and hence, compliance with the prescribed VOC emission limits, the access pores in the macro- and meso-pore range facilitate desorption of the solvents from the activated carbon.

The activated carbon is charged in fixed-bed adsorbers and should offer as low a flow resistance as possible. This is the reason why 4mm extruded carbon pellets are the adsorbents of choice for this application. Depending on the type of solvent to be removed, activated carbon grades of different raw material origins or low-ash carbon grades are employed to give the best treatment result.

https://www.donau-carbon-us.com/Pro...Luft-und-Gasreinigung/Losemittelruckgewinnung

Click to expand...

It is not that I want to prevent all vapors from escaping, but more that I want to limit large releases. It would be great if the solvents naturally purged themselves over time from the carbon.

Gray Wolf said:

Industrial Ventilation recommends 100 to 200 surface feet capture velocity, and 1000 cfm slot velocity.

Click to expand...

I see how to calculate the face velocity, but how is the slot velocity calculated? My friend can have metal laser cut in any pattern via CAD, and I planned to just copy the slotting pattern found in some of the $$,$$$ models.

SkyHighLer said:

The fan doesn't need to be explosion proof to be effective, the rating only means in case of an external explosion the fan motor is protected from the flames reaching the windings, and hopefully it will continue to function.

Attic gable mount exhaust fans are an inexpensive high CFM choice.

Click to expand...

Do you think the Hyperfan that I listed would be an acceptable option for this application with the solvents that I listed above?

SkyHighLer said:

The fan doesn't need to be explosion proof to be effective, the rating only means in case of an external explosion the fan motor is protected from the flames reaching the windings, and hopefully it will continue to function.Attic gable mount exhaust fans are an inexpensive high CFM choice.

Click to expand...

Ummmm, you are at times pulling fumes within the LEL of the solvent. If the motor is in the air stream, it needs to be enclosed or sparkless.

It's isn't about the flames reaching the windings, it is about the slip ring sparks igniting the fumes.

WaterFarmFan said:

I see how to calculate the face velocity, but how is the slot velocity calculated? My friend can have metal laser cut in any pattern via CAD, and I planned to just copy the slotting pattern found in some of the $$,$$$ models.

Click to expand...

If you wish to design exhaust systems, I highly recommend picking up a used copy of Industrial Ventilation, a manual of recommended practices, by the American Conference of Governmental Hygienists. I still use a 17th edition, which still works.

It is the standard for the industry and the bible that we used in aerospace to design ventilation and exhaust systems precisely by the numbers.

If you have to move 900 cfm from a 3' wide exhaust plenum, and you want the velocity at 1000 surface feet,

Since the air stream is moving at 1000 surface feet and you have to move 900 cfm, you need .9 square feet of slot.

900cfm/1000sf = .9 square feet of slot opening.

.9cu/ft/3' slot length = .3 feet slot width

.3' X 12 = 3.6" wide

3.6"/ number of slots = individual slot width

WaterFarmFan said:

Do you think the Hyperfan that I listed would be an acceptable option for this application with the solvents that I listed above?

Click to expand...

What are the specifications for the Hyperfan? You want your fan to have adequate cfm, at the static pressure that you are operating with. For our application it will take a centrifugal fan.

Here is a link with some of the design criteria and formulas:

https://www.captiveaire.com/manuals/airsystemdesign/designairsystems.htm

WaterFarmFan said:

Most helpful. Do you have a photo of the completed box and air knife portion? Is it basically a large lip in front?

Click to expand...

You can't get a good view of the air knife, but here is a view of the open cabinet showing the back of the knife and the plenum face with one slot at the bottom and one near the top. Air inlet is out the side of the building.

WaterFarmFan said:

Will check that out. I have to be as stealthy as possible, so a tall stack is probably out. I was thinking about creating a ducting system with two paths right off the hood using wye branches. I would only use carbon for the most hazardous solvents and sensitive times of the day, with the damper open for the rest. Something like this maybe:

Click to expand...

In addition to a tall stack with an evase discharge to mix the air, you can also add odor. A ghetto scrubber for grows, used to be a box full of toilet bowl crystals for the air to blow through.