A gallery of home built hoods and fume scrubbers _hood_

[4metals]

3, 'The blue line is vacuum and is selected at the valve by the vacuum generator. Each 1/2" vacuum port needs a shut off valve and a PVC barbed fitting.' I really don't understand if this would be needed... I would be highly grateful for your response as I'm brain cooked at this point of trying to make this thing work properly.

The blue line is to use the same vacuum source to pull suction for filtration and solution transfer. The valves are needed to separate the vacuum going to the scrubber from the vacuum going to the filtration suction line (blue). They cannot be used at the same time because the vacuum is not strong enough to supply adequate CFM for both. Similarly but not shown, shut off valves should be on the blue pipe that runs through the hood where little blue circles indicate ports to install suction shut off valves. If you are using the system for filtration having one suction port in use and the other open will result in no vacuum as the vacuum air takes the path of least resistance . That is why we need valves.

 

[Yggdrasil]

Hello sir,

My mind this past week had been so clogged that I completely missed this one and now I think this is probably the closest of how I can imagine my setup to be like given what I have already built.

I do have questions here :

1, The overhead blower does not seem to be connected to the red pipes, so what is its main purposes here? the regular fumes of the hood only?
2, The red pipe does not have any suction or blowing therein as can be seen, so is the science of the entire unit being taken care of by that lone pump at the bottom right end only?
3, 'The blue line is vacuum and is selected at the valve by the vacuum generator. Each 1/2" vacuum port needs a shut off valve and a PVC barbed fitting.' I really don't understand if this would be needed... I would be highly grateful for your response as I'm brain cooked at this point of trying to make this thing work properly.

Many thanks in advance.

To simplify 4metals answer.
Both the red and the blue line is vacuum lines and the colomns are the flask train.

 

[4metals]

I have edited the image to include the vacuum system working to filter a solution. Please keep in mind it can be one or the other, scrub fumes or filter solutions. Open and close valves accordingly.

 

[J.Najam]

The overhead pipe (black in the drawing) is for what the EPA refers to as fugitive emission, it is separate from the scrubbed emission which is indicated with the red pipes.

Oh okay

The red pipe is powered by a venturi (actually a water powered venturi also called an eductor). The eductor is powered by the pump which recirculates water through the eductor to generate suction which transferred into the red pipe.

I think I now understand the concept of an eductor for vacuum generation. I really had no idea how it works, although its late here, but I'll just be on my way to carry a baby experiment with a water pump I have to fully grasp the concept.

Both the red and the blue line is vacuum lines and the colomns are the flask train.

Ah yes but if I understood it correctly both these pipes are obviously for different purposes. While the red goes to the scrubbers, the blue is an extension of the scrubbing unit in terms of only using its vacuum for filtration. But this one I think will be challenging for a novice in my situation so Ill just use a regular gas suction pump that I have. They're not non-corrosive but they're cheap so Ill just keep buying once they're about to die down. Their sound of the coil and machine is a tell. I've used these a lot for past filtrations.

I have edited the image to include the vacuum system working to filter a solution. Please keep in mind it can be one or the other, scrub fumes or filter solutions. Open and close valves accordingly.

Really appreciate it sir! I cant thank all of you enough.

On the other hand, looking at my own setup. I'm thinking 2 possibilities :

1, replace the 3inch pipe of the blower and use a 1 or 2 inch pipe with openings for suction in a closed system with a pvc tube flask train as as shown in these diagrams above.

2, build a scrubber with buckets using the same setup as blower from the left with a venturi into the fumehood as it already is and then lower the pipe into bucket trains as well as eductor suction from the other end?

 

[J.Najam]

Which of these would be better suited for scrubbing? 10 mason jars 7inch by 3.4inch or 5 buckets 7.6inch by 7.6inch?

 

[Yggdrasil]

Which of these would be better suited for scrubbing? 10 mason jars 7inch by 3.4inch or 5 buckets 7.6inch by 7.6inch?

What kind of scrubbing do you think of?
Bottle train or general scrubber?
If you think for the main flow from the hood you need something that leys that volume spend 9 seconds to pass through.

 

[J.Najam]

What kind of scrubbing do you think of?
Bottle train or general scrubber?
If you think for the main flow from the hood you need something that leys that volume spend 9 seconds to pass through.

Oh no not for the hood. Train for reactions

 

[Yggdrasil]

Oh no not for the hood. Train for reactions

Check this thread it has been given to you long time ago.

Even 4metals drawing show it.

Any strong tall bottle that can be made airtight or pvc pipes capped in one end and screwcap in thevother end with two holes for tubes.

 

[J.Najam]

Check this thread it has been given to you long time ago.

Even 4metals drawing show it.

Any strong tall botle that can be made airtight or pvc pipes capped in one end and screwcap in thevother end with two holes for tubes.

Oh yes, Im aware of it. Just checking if these available items are feasible enough for effective scrubbing or no. Otherwise Ill just go with the PVC pipes.

4metals got 4ft pipes of 4 inches in thickness. That'll be too much for me to handle. Given he changed the chemistry 'everyday' due to the nitrate crystals thay would form. Also my material may not be that much in play at the moment.

Just double checking this one if it would be enough

Which of these would be better suited for scrubbing? 10 mason jars 7inch by 3.4inch or 5 buckets 7.6inch by 7.6inch?

 

[Yggdrasil]

Oh yes, Im aware of it. Just checking if these available items are feasible enough for effective scrubbing or no. Otherwise Ill just go with the PVC pipes.

4metals got 4ft pipes of 4 inches in thickness. That'll be too much for me to handle. Given he changed the chemistry 'everyday' due to the nitrate crystals thay would form. Also my material may not be that much in play at the moment.

Just double checking this one if it would be enough

Nothing you have here are suited.
You want tallish containers, they can be thin but should be tall.
Next, they do not have to be inside the hood, only the reaction vessel/beaker need to be in the hood.

 

[J.Najam]

Nothing you have here are suited.

Well thats sad, I thought I could put it to use.

You want tallish containers, they can be thin but should be tall.

but yeah sure, Ill go with this

Many thanks!

 

[Yggdrasil]

Well thats sad, I thought I could put it to use.

but yeah sure, Ill go with this

Many thanks!

Of course you can put the to use but not for this, and not for heated reactions.

 

[J.Najam]

You want tallish containers, they can be thin but should be tall.

Alrighty, I got this done. Have about three cylinders capped above and below, Each of them is 2 ft in height and hold about 3 litres of water. Just wanted to check I think 4metals mentioned the use of marble chips as a good idea for retention time... But I may have missed how much do we really add to each ? 1/4th 1/2 or full.. like what was the ratio here?

Thanks

 

[4metals]

I think 4metals mentioned the use of marble chips as a good idea for retention time...

No, the marble chips are for the reservoir where you pull a vacuum with a venturi. And the scrubbing benefits from retention time so you need to know the CFM of the fume you are sucking through the system and size your scrubbing towers accordingly. A tower packing like bio balls (used in aquarium filters) will slow down the bubbles increasing retention time.

 

[Yggdrasil]

No, the marble chips are for the reservoir where you pull a vacuum with a venturi. And the scrubbing benefits from retention time so you need to know the CFM of the fume you are sucking through the system and size your scrubbing towers accordingly. A tower packing like bio balls (used in aquarium filters) will slow down the bubbles increasing retention time.

If I'm not mistaken, that is what he aims for now since has 3 capped cylinders.

 

[Yggdrasil]

Alrighty, I got this done. Have about three cylinders capped above and below, Each of them is 2 ft in height and hold about 3 litres of water. Just wanted to check I think 4metals mentioned the use of marble chips as a good idea for retention time... But I may have missed how much do we really add to each ? 1/4th 1/2 or full.. like what was the ratio here?

Thanks

Remember you need two pipes in one cap.
One goes to the bottom and is the inlet and one is well out of the liquid and that is the outlet to the vacuum side.

 

[J.Najam]

If I'm not mistaken, that is what he aims for now since has 3 capped cylinders.

Yes chief, this is what it is now.

Remember you need two pipes in one cap.
One goes to the bottom and is the inlet and one is well out of the liquid and that is the outlet to the vacuum side.

yep, its exactly like that. Only that I have inserted nozzles Instead of pipes atop each cylinder with a single pipe that runs toward the bottom end attached to the nozzle. ill share pics soon.

A tower packing like bio balls (used in aquarium filters) will slow down the bubbles increasing retention time.

Sir this is where I asked for the marble chips as I have them lying around.. if thats not good enough may I use cat litter or glass marbles? Would that be good enough here?

Bio balls down here are a bit pricey and I doubt if they'd be enough for even a single packing.

Also I may use the reservoir eductor in the very near future as I found out that my vacuum pump goes hot in an hour of operation only. May burnout soon. Which is why Ill get things running for now and build my self a water pump for the same in the meantime.

 

[4metals]

Sir this is where I asked for the marble chips as I have them lying around.. if thats not good enough may I use cat litter or glass marbles? Would that be good enough here?

Definitely not cat litter. Glass marbles are inert and will slow the flow through the column. I have seen marble chips used as tower packing in a tower where the air flows through a wetted packing (marble chips) but never where the chips are immersed in a wet based column. They will dissolve slowly and help maintain an alkaline pH. You should be careful as they may cause excessive sedimentation as they dissolve and may cause clogging of the pipes. Actually if you totally ignore maintenance of your scrubbing device a caustic fed scrubber will also clog.

 

[J.Najam]

Glass marbles are inert and will slow the flow through the column.

With due respect, but isn't this what we should be going after in order for increased retention

They will dissolve slowly and help maintain an alkaline pH.

Also this one, it may assist in not having to add too much chemistry every 2 - 3 days.. although yes maintenance would be a must even if not adding these chips as you have mentioned. I may have to carry out the maintenance manually until I install the valves on the bottom half but this is a must. Not ruling it out. Definitely have a thought process to carry that out. Will be time consuming though...

Actually if you totally ignore maintenance of your scrubbing device a caustic fed scrubber will also clog.

So what do you advise on the packing inside these cylinders? After your advice if I were to use anything brittle, it would clog up my system indefinitely.

Many thanks

 

[J.Najam]

Would these work?