A gallery of home built hoods and fume scrubbers _hood_

[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?

 

[4metals]

Would these work?

Marble chips are usually white, those do not appear to be marble, which is recrystallized limestone.

 

[4metals]

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

Yes but a spherical glass marble has less surface area than a structured packing like bio balls. And the surface area is what helps with retention time. Glass marbles will work if you have nothing else. I have seen whiffle balls used as well as hair curlers and short segments of PVC pipe. Just use whatever is inert and has a lot of surface area.

 

[J.Najam]

Marble chips are usually white, those do not appear to be marble, which is recrystallized limestone.

Yes sir, I know I have the marbles but I shared these pebble pics as Ill have to make a purchase. They come cheap. Otherwise Ill have to go miles out towards the other side of the city to get them for free..

I have seen whiffle balls used as well as hair curlers and short segments of PVC pipe.

I do have an idea of what you're saying, ive seen it too. Not as in scrubbing though but in fish tanks as bio balls.. Would these ceramic bio balls work?

 

[4metals]

Would these ceramic bio balls work?

The ceramic bio balls you pictured would not work well for a few reasons. First, they are porous because their intent is to have bacterial populations grow on and in the pores. What we are looking for is a non porous substrate that is insoluble and creates a large surface area for the chemical reaction to take place. The porous ceramic bio balls will not be ideal.

Yes sir, I know I have the marbles but I shared these pebble pics as Ill have to make a purchase. They come cheap. Otherwise Ill have to go miles out towards the other side of the city to get them for free..

You have the marbles or you have the pebbles which you showed in the photo? If you have no alternative I would use the glass marbles and not the pebbles. I am sure the staff at GRF feels terrible, as I do, that you may have to go out of your way to get glass marbles, but it is what it is.

 

[J.Najam]

First, they are porous because their intent is to have bacterial populations grow on and in the pores. What we are looking for is a non porous substrate that is insoluble and creates a large surface area for the chemical reaction to take place. The porous ceramic bio balls will not be ideal.

Ohh alright alright.. it's very interesting to learn a new thing everyday.

You have the marbles or you have the pebbles which you showed in the photo? If you have no alternative I would use the glass marbles and not the pebbles. I am sure the staff at GRF feels terrible, as I do, that you may have to go out of your way to get glass marbles, but it is what it is.

I'm awfully grateful for the concern of the staff here as it is... Actually it was the pebbles that I had to go over to the other side but you just saved me that trip!! Although i do have the marbles I still have to find them.

As of now I'm in the process of perfecting the last end of my scrubber. I'm figuring out whether vacuum pump or venturi. I'm done testing the pump and now I need to figure out the pressure of the venturi. My diaphragm water pump gives me 5.5L/min, would that be enough to generate the required pressure to create the vacuum??

Many thanks for your time again

Edit: grammatical errors

 

[J.Najam]

Hello again,

Im trying to create a spiral inside my cylinders for added retention but im facing a problem. Thep pipes tend to bend instead of the curve. What do I do to fix this issue to obtain a more of a uniform curvature all the way to the top, does anyone have an idea? The pipe im using is the orange ponaflex hose pipe 8.5mm 2250 PSI

Thanks!

 

[4metals]

Correct me if I am wrong here but is the tubing you are using is to deliver the fume to the bottom of scrubber cylinders? If so, being any longer (by being in a spiral) will not do you any measurable good. The retention time for fume in a column is the time the fume spends in contact with the chemistry in the cylinder not the time it takes to get there.

 

[J.Najam]

Correct me if I am wrong here but is the tubing you are using is to deliver the fume to the bottom of scrubber cylinders? If so, being any longer (by being in a spiral) will not do you any measurable good. The retention time for fume in a column is the time the fume spends in contact with the chemistry in the cylinder not the time it takes to get there.

Yes sir you're absolutely correct, that is what i intend to achieve here.

Also if I'm not mistaken, I drew inspiration from one of your older posts. I dont remember where I read it but it was one of your posts where you suggested a spiralling scrubber since the tubes may also hold some chemistry being a part inside it. I hoped to achieve the same for some added retention if any.

Im only a little skeptical of the time the fumes may spend in the these cylinders, hence my thought came down to this.

 

[4metals]

The spiral riser I was referring was in an older style gas scrubber used to convert mixed cyanide gasses into sodium cyanide for analysis. The spiral was a glass upside down screw shape that allowed bubbles to spiral upward in the solution and increase the contact time. Different application but the gas being treated is exposed to the solution, your thought would not allow the contact.

 

[4metals]

When @J.Najam finishes his hood I will break off the last 3 or so pages of this thread into a separate thread and just add a photo of his completed hood to this thread as the original intent here was to show a gallery of working hoods of our members and not detail the design.

 

[J.Najam]

The spiral riser I was referring was in an older style gas scrubber used to convert mixed cyanide gasses into sodium cyanide for analysis. The spiral was a glass upside down screw shape that allowed bubbles to spiral upward in the solution and increase the contact time. Different application but the gas being treated is exposed to the solution, your thought would not allow the contact.

Ohh alriight.. must've been a mistake. But then I carried out some earlier tests using this, and I noticed a backflow of water. Wouldn't it be possible that the tubes could infact be holding the chemistry inside it as well?

My finger is at the point where the tube is attached allowing an intake of the fumes.