A gallery of home built hoods and fume scrubbers _hood_

[J.Najam]

Hello,

Long time coming I think Im almost done here.. if there is something that Im missing I would love to know.

The cut pvc in the bucket, I will use as the packing for the scurbbing cylinders.

Also I decided to use these cups in the last image for the bottom of my cylinders, in order to not let the packing clog the opening of the valve. It has holes in it to let the air travel, i did some test runs and the airflow seems fine but I did notice that some bubbles stay in there even after shutting off the pump. When I shake the cylinders I feel some movement inside of it like a tell that some bubbles just left the cup. So let me know of it still is OK to carry on?

Many thanks for your time again.

 

[J.Najam]

Cut a small opening.
Put in some glass and let the light be on the outside.

Yep. Done

 

[4metals]

Please, Stand back a bit and take a photo so we can see the perspective of the hood and the scrubber.

 

[J.Najam]

Please, Stand back a bit and take a photo so we can see the perspective of the hood and the scrubber.

Alright, ill try my best to make it easy. Unfortunately the lane is very narrow so this is as far as I can take. But I'll take different shots

 

[Yggdrasil]

Hello,

Long time coming I think Im almost done here.. if there is something that Im missing I would love to know.

The cut pvc in the bucket, I will use as the packing for the scurbbing cylinders.

Also I decided to use these cups in the last image for the bottom of my cylinders, in order to not let the packing clog the opening of the valve. It has holes in it to let the air travel, i did some test runs and the airflow seems fine but I did notice that some bubbles stay in there even after shutting off the pump. When I shake the cylinders I feel some movement inside of it like a tell that some bubbles just left the cup. So let me know of it still is OK to carry on?

Many thanks for your time again.

Hmm.
What system are you using here?
Vacuum or flow through?

 

[J.Najam]

Well I got some new clicks here, this is the best I could do in the space I have.

1 and 2nd picture is the perspective of my fumehood. The chair there is referential to the space between the hood and the wall.

3rd, the fumehood itself.

4th and 5th the scrubbing system

6th the issue : i noticed the wall has cracks and initially I planned on getting the exhaust pipe next to the other two. But since there seems to be danger so now im thinking of creating a loop around the whole cabinet. I may have to insert an extra blower midway to ensure the air throw is proper out the exit.

I would also like a suggestion on the position of the exhaust fan. I ran a couple of tests and it seems like the fumes are being drawn from under the funnel too. I used a cigarette, stuck it in ash tray and placed it inside the beaker and covered it with a watchglass. The emissions were barely going up the funnel and more in the fan. Although it will be tough to get carve another hole manually, but if need be I ll do it. So let me know if it will be needed or there can be another way.

Hmm.
What system are you using here?
Vacuum or flow through?

Im using the vacuum system here. What would be flow through again sorry?

Many thanks for your time again.

 

[Yggdrasil]

Well I got some new clicks here, this is the best I could do in the space I have.

1 and 2nd picture is the perspective of my fumehood. The chair there is referential to the space between the hood and the wall.

3rd, the fumehood itself.

4th and 5th the scrubbing system

6th the issue : i noticed the wall has cracks and initially I planned on getting the exhaust pipe next to the other two. But since there seems to be danger so now im thinking of creating a loop around the whole cabinet. I may have to insert an extra blower midway to ensure the air throw is proper out the exit.

I would also like a suggestion on the position of the exhaust fan. I ran a couple of tests and it seems like the fumes are being drawn from under the funnel too. I used a cigarette, stuck it in ash tray and placed it inside the beaker and covered it with a watchglass. The emissions were barely going up the funnel and more in the fan. Although it will be tough to get carve another hole manually, but if need be I ll do it. So let me know if it will be needed or there can be another way.


Im using the vacuum system here. What would be flow through again sorry?

Many thanks for your time again.

For a vacuum system there is not much need of packing's.
Only liquid and since you have 5 cylinders there is plenty of retention time.
Flow through, is where you put all your air from the hood through scrubbers with packing.
If there is not enough vacuum the air/fumes from the reaction vessel will not be dragged through the funnel.
How much vacuum do you have?
Maybe you need to bypass two of your cylinders?

 

[J.Najam]

For a vacuum system there is not much need of packing's.

With due respect, I guess I may have mentioned it earlier that Ill be using a vacuum pump for suction and the packing discussion followed...

Only liquid and since you have 5 cylinders there is plenty of retention time.

This sounds as a relief

Flow through, is where you put all your air from the hood through scrubbers with packing.

got it maybe in the future

If there is not enough vacuum the air/fumes from the reaction vessel will not be dragged through the funnel.

i have done many tests without the presence of the fan. The fumes were being dragged in through the funnel just fine. But now when everything is put together, the fan just seems to be an overkill. Im doubting it is probably its position in the hood is all.

Maybe switch it off when undergoing the regular vacuum suction operation. Would that be safe enough?

Maybe you need to bypass two of your cylinders?

3 tall ones are regular and will be filled with NaOH. The smaller glass bottle is for the backflow and the taller one is basically a tell for the vacuum strength. Since each has their own purpose, I wouldn't want to disturb it

Thanks for your time

 

[J.Najam]

Hello again,

So my dad wont lend me his cigarettes anymore for these tests as they were all being wasted. So I tried again today with boiling water as another test. I wish Id taken some clicks but Id like some clarification as per my observations :

1, the fumes tend to condense and form drops around the inside ring of the funnel and they then drop onto the hotplate. What is suggested to combat this concern?

2, the vacuum started to function alright. The glass bottles were a great tell as initially the bottles had some smoke coming in and then it started to condense into vapours. However, I noticed considerable emissions from the funnel, are they supposed to go upstream into the funnel too or should I just make peace with it and move on? Like both things are happening, the vacuum is pulling it but there are noticeable emissions too.

Many thanks for your time again

 

[Yggdrasil]

Hello again,

So my dad wont lend me his cigarettes anymore for these tests as they were all being wasted. So I tried again today with boiling water as another test. I wish Id taken some clicks but Id like some clarification as per my observations :

1, the fumes tend to condense and form drops around the inside ring of the funnel and they then drop onto the hotplate. What is suggested to combat this concern?

2, the vacuum started to function alright. The glass bottles were a great tell as initially the bottles had some smoke coming in and then it started to condense into vapours. However, I noticed considerable emissions from the funnel, are they supposed to go upstream into the funnel too or should I just make peace with it and move on? Like both things are happening, the vacuum is pulling it but there are noticeable emissions too.

Many thanks for your time again

If your vacuum is correct all the fumes should go through your flask train

 

[tsfarley]

I decided to start the 2nd half of my ewaste hobby by building a small vented hood.
I had 4 or 5 of the old black table tops (1950's) from a school chem lab, so those limit my depth to about 24inches (61cm). I also found some 1/4 inch plexiglass extremely cheap which was 24in wide also, so that is working.

I wanted to be able see in the sides, so those are plexiglass also. For the front, I just plan to have a plexi panel slide up and down in a small channel.

The back is plain 5/8 plywood as well as the back half (12in) of the top. The front will be plexiglass also.
The end size will be about 24in deep, 32 in wide, 30 in high.
Top will have a 4" pvc duct feeding out to the back of the barn. I'm still laying out the venturi vacuum plans. (yes, I'll be reviewing all GRF posts for that. )
I'm considering a backup fan system at the end of the line outside in case the venturi system fails during operation.
something like flip a switch and the 2ndary fans come on while opening a 2nd exit port outside. soon I will start on a fume cleaning system for outside.

it's been fun collecting pins, chips, cpus, boards, ram, etc. but I really don't have a clue on what it may be worth down the road; so here goes nothing!

I had just planned on caulking the seams and corners. Is any caulking best for acid fume environment?

Should I paint all the wood with something special?
Has anybody found that they just really need 36 or 48" wide hoods and smaller is a pain?
I'll finish this one and start on a 2nd larger one later; first I need to finish up a small ADU for my daughter (background of pics).
Being retired is excellent.
feedback, criticism is welcome.
more pics to follow as I progress.
Tim

 

[geoffrod]

So long time reader new poster,
I am just starting to build a small fume hood and wet scrubber setup, something in the vein of the pictures provided by @4metals and others.
The cabinet im using a 410mm wide opening x 705mm high x 545mm depth, its a cabinet i am repurposing an will do what i need to start with, i am planning on having a hot plate with a 2000ml beaker for reactions and collection of fumes into the scrubber.
I might be a little tight but im not planning on running much to start. the idea is to setup a safe way of working.
I will be running a 6" inline fan thru a venturi (cut off funnel) drawing the air flow out of the box.
the main vacuum for the reaction beaker will be handled with a water eductor using a double diaphragm pump, 12L/min 130 psi. this will hopefully create enough vacuum to pull the fumes thru the wet scrubber canisters, well thats the plan, everything is in test mode atm.
attaching a few photos and a video of smoke getting drawn up the fume exit.
i look forward to adding more pics as the build goes along.
Edit - added pump pics

 

[Yggdrasil]

So long time reader new poster,
I am just starting to build a small fume hood and wet scrubber setup, something in the vein of the pictures provided by @4metals and others.
The cabinet im using a 410mm wide opening x 705mm high x 545mm depth, its a cabinet i am repurposing an will do what i need to start with, i am planning on having a hot plate with a 2000ml beaker for reactions and collection of fumes into the scrubber.
I might be a little tight but im not planning on running much to start. the idea is to setup a safe way of working.
I will be running a 6" inline fan thru a venturi (cut off funnel) drawing the air flow out of the box.
the main vacuum for the reaction beaker will be handled with a water eductor using a double diaphragm pump, 12L/min 130 psi. this will hopefully create enough vacuum to pull the fumes thru the wet scrubber canisters, well thats the plan, everything is in test mode atm.
attaching a few photos and a video of smoke getting drawn up the fume exit.
i look forward to adding more pics as the build goes along.

Two things strike me.
Since most of the reaction gases/fumes are heavier than air, the suction should be at the lower part of the hood.

Next I think that the funnel might need to be opened more.
I'm afraid it will create too much back pressure on the flow from the fan.
You are the one seeing this live and it is easy to adjust.

Besides that it seems good.

Edit to add:

It is wise to duct the intake air directly from outside, not the same room as the hood are placed in.

 

[geoffrod]

Two things strike me.
Since most of the reaction gases/fumes are heavier than air, the suction should be at the lower part of the hood.

Next I think that the funnel might need to be opened more.
I'm afraid it will create too much back pressure on the flow from the fan.
You are the one seeing this live and it is easy to adjust.

Besides that it seems good.

Edit to add:

It is wise to duct the intake air directly from outside, not the same room as the hood are placed in.

Thanks so much for your reply, greatly appreciated and taken on board. The fumes being sucked out are planned to be anything rogue that doesnt get taken to the scrubbers, which hopefully will not be much at all.
I take your comment about the funnel, i have increased it twice already, as the fan being used cant handle compressing so much, i was reluctant to cut too much more from it as i was thinking i needed the end of the funnel to be as far along the exit tube as it could be? but there is definitely backpressure already there as you rightly state. More modifications required i guess.
Regards
Geoff

 

[Shark]

Can't really tell how long your funnel is but something like this one on Amazon might work.

Long Funnel