A gallery of home built hoods and fume scrubbers _hood_

[Martijn]

My hood. It is made of plywood coated with boat lacquer and an epoxy trespa sheeted piece of wood as a work bench. It does not like sulfuric.
The backplate has a wooden air devider to suck air from the top and the bottom, sliding the back to set the ratio.

The curved door with acryl windows slides up and is balanced with some lead sheets rolled around a threaded steel rod. The rolls are held in place by nuts and big washers. A piece of pvc pipe guides it up and down.
My fan blows air in a venturi so any corrosive fumes don't go through the fan.
The venturi is made of a pvc Y-piece and a tapered plastic cup inside, bottom taken out off course.

The lighting is a watertight outdoor armature to keep corrosive gases out.

I had some sockets inside to connect power leads for electrolysis in the top left, but they corroded fast, so I don't use them anymore.
All together it served me well the past ten years.
I recently expanded my lab to make room for a sulfuric cell and a silver stripping cell and more storage room. The cells only need good ventilation so there is no hood on that side.

 

[4metals]

I never would have thought about using a cone with out one of the members here.

I used a traffic cone for making an eductor, and my son never let me forget stealing his traffic cone! I used it for a venturi but not a reducer. It can work as a reducer as long as you cut open the discharge side so as not to restrict airflow.

 

[bloodmoneybullion]

I used a traffic cone for making an eductor, and my son never let me forget stealing his traffic cone! I used it for a venturi but not a reducer. It can work as a reducer as long as you cut open the discharge side so as not to restrict airflow.

well either way you solved the problem i had, i tried to use it to create a venturi but i failed every configuration i tried even added a duct booster fan and still got back draft i think i restricted the air too far too fast but with this style blower there was no way to make it work. going from 10" to 4" didnt cut it im thinking about just going 6" from the blower all the way to the roof instead of 4". i really dont expect to be using the hood very much ill be lucky to get a batch to refine once a month and probably not alot at any one time so im hoping my wet scrubber will capture most everything safely. i know my setup isnt preferred by anyone who knows what they are doing as made clear by Yggdrasil whos been pretty critical of my efforts but for a beginner and learner i think the whole setup is quite nice actually and should last several years before needing any maintenance. once i rebuild and install the wet scrubber ill post a final picture

 

[4metals]

i know my setup isnt preferred by anyone who knows what they are doing as made clear by Yggdrasil whos been pretty critical of my efforts but for a beginner

I doubt Yggdrasil was being critical, more like he is trying to get you to do it right the first time. Perhaps he confused you with another member called Skinny who has a similar setup. But Skinny left in frustration insisting he could get better help elsewhere.

 

[Shark]

Yggdrasil has been on the forum a long time and often new members think he is being rude when most often it is just language translation issues. This is an international forum even though English is the preferred language for many members as it translates easier to other languages.Still translators aren't perfect.

 

[galenrog]

Yggdrasil has been on the forum a long time and often new members think he is being rude when most often it is just language translation issues. This is an international forum even though English is the preferred language for many members as it translates easier to other languages.Still translators aren't perfect.

Agreed. Yggdrasil is Norwegian. Although he uses English quite well, nuances in the written word can be quite difficult to communicate.

Time for more coffee.

 

[ólom]

I never felt rude. He always helped me a lot!

 

[bloodmoneybullion]

Here it is with a working Venturi effect using the cone. It's inserted in the top wye joint and pulls any excess fumes off the vacuum powered wet scrubber as well as pulls from the fume hood. I know I can now use the Venturi to save my blower but I really am not worried about it it's pretty well protected as long as the motor doesn't over heat like it did for auggiedog.

 

[4metals]

To be clear, it appears that you have the blower mounted on its side so the air intake is 100% over the hood exhaust port? If this is true it will never function as a venturi as the concept of a venturi is to compress the air as it passes over the hood exhaust port and allow the air to decompress and draw extra air from the hood exhaust port. Since you are taking 100% of the intake air, or so it appears, all the cone is doing (aside from allowing you to fit different size pipes together) is restricting airflow. If you cut the cone narrow opening so it is the size of the pipe, you will draw more air, not as a venturi, but as a less restricted air path.

 

[Yggdrasil]

To be clear, it appears that you have the blower mounted on its side so the air intake is 100% over the hood exhaust port? If this is true it will never function as a venturi as the concept of a venturi is to compress the air as it passes over the hood exhaust port and allow the air to decompress and draw extra air from the hood exhaust port. Since you are taking 100% of the intake air, or so it appears, all the cone is doing (aside from allowing you to fit different size pipes together) is restricting airflow. If you cut the cone narrow opening so it is the size of the pipe, you will draw more air, not as a venturi, but as a less restricted air path.

I think his venturi is on the side branch to vent the fumes from the vacuum system.
But by restricting the blower he will get less effect in the main hood.
Another thing is that he might want to run the intake in the hood behind a baffle plate so it sucks the air from the bottom back.

 

[4metals]

OK so the orange coupling isn't the cone it is just a coupling. The venturi is totally enclosed in the pipe. That can work. Usually I try to get the full force of the fan as close to the cone as possible. I'm sure @bloodmoneybullion will let us know how it works.

 

[SRM]

My first hood was based on a discarded fiberglass shower enclosure. I cut it down, fabricated a top and a door. I left the drain in, cut a hole in the table and used a plastic grid to allow drainage into a catch bucket for any spills. I laid some tile pieces on the grid for heat resistance and cut a 4-inch (100mm) vent for ducting to the scrubber.