Fume hood venturi.

[DJPGold]

Hello folks,

Well thank you all again for a great read, [ the sound of applause in a large hall ]. I realize that my post is over a year late but none the less this
information was just what I was looking for. And eeTHr , you did a bang up fantastic job. As I was rounding up on page four of this thread and
heading down it I had a really good idea of what you had found worked the best. I couldn't help but think, "why doesn't he draw it up". And I almost did
because this sounded just like what I have been mulling over at the shop.
Then I saw this draft of yours towards the middle ::

http://img703.imageshack.us/img703/574/suctionventuri7.jpg

Bingo! Just what I thought. But then came this one from you ::

http://img819.imageshack.us/img819/589/suctionventuriammentype.jpg

Perfect!!! We owe you one for your work eeTHr. This has helped me out BIG TIME. I was originally going to run with the first design pic. Like
I said, I had that in my head at first but thought I'd look into some sort of confirmation to the design. So I went a searching... This Forum and
the Web. That's when I found this thread, thank goodness.
I noticed the Ammen pic in the beginning of this thread that jimdoc posted ::

http://www.goldrefiningforum.com/phpBB3/download/file.php?id=9933&t=1

I thought it was great. Then spent a quite a while looking into that... You summed it up well with your tests.

So eeTHr you mentioned, at the end of page five the "gap area" of the 2" in the 3" Wye. I think a 4" Wye could be used as well to compensate for
that issue. And the point that Geo made was fantastic, "the pressure going in works better at the exhaust end", (page five). Not only a great point
but would be easy to do if one does like you mentioned further down in the "gap area" post, "using 4" ducting", might pan out quite well if one needed
to shove that 2" pipe a little more down stream. Ok, I am set. Thanks again folks...

[ evL ]

Nearly 10 years later. I’ve just finished reading these 6 pages, and I feel as if everyone understands it better except me the diagram links are broken, could someone please fix them if possible before I have to bust out the pencil and paper to see if understand the system correctly

 

[FrugalRefiner]

I was able to fix a few links, but probably not the ones you wanted. eeTHr had posted a lot of links to images on ImageShack, but the images are no longer there. eeTHr hasn't been here since 2014.

Dave

 

[DJPGold]

I was able to fix a few links, but probably not the ones you wanted. eeTHr had posted a lot of links to images on ImageShack, but the images are no longer there. eeTHr hasn't been here since 2014.

Dave

No worries, thank you. I was hoping at the end of this thread there would be a conclusion on what works for the Venturi/eductor exhaust but yeah no luck. I think I’ll take this design from Kurtak and hope it works

 

[FrugalRefiner]

Take a look in The Library. There are a few threads on hoods, ducting, and scrubbers.

Dave

 

[DJPGold]

Hopefully anyone who has experience with Venturi fume hoods can help me out here I’m wondering if I would get away with shortening the air input tube from 1m to a couple hundred mm without a negative effect. My thinking is that it would decrease drag and improve the blower force closer to the output.

The red line marks roughly where the tube ends, and green marks the section I would like to cut.

 

[Yggdrasil]

Hopefully anyone who has experience with Venturi fume hoods can help me out here I’m wondering if I would get away with shortening the air input tube from 1m to a couple hundred mm without a negative effect. My thinking is that it would decrease drag and improve the blower force closer to the output.

The red line marks roughly where the tube ends, and green marks the section I would like to cut.

I can't see a problem with that.
For performance the only important thing is the speed increase through the actual venturi and a pressure drop "Vacuum" just after,
when the speed goes back to normal. But I think the red line needs some more space to be effective.
You can clearly see the different diameters.
And the output end should have as little restrictions as possible.

 

[kurtak]

Hopefully anyone who has experience with Venturi fume hoods can help me out here I’m wondering if I would get away with shortening the air input tube from 1m to a couple hundred mm without a negative effect. My thinking is that it would decrease drag and improve the blower force closer to the output.

The red line marks roughly where the tube ends, and green marks the section I would like to cut.

First of DJPGold - could you please keep ALL of your questions concerning building a fume hood in ONE thread

Mods - could one of you please combine ether this thread with his other thread - or - the other thread with this one

the other thread is ------------

https://goldrefiningforum.com/threads/fume-hood-venturi.10979/page-7#post-338166
IMO - this one should be combined with the link above as the link above is already a longer & more in depth discussion about fume hoods which in turn takes other members to a more detailed discussion as we move forward in fume hood discussion to help answer DJPGold's questions

Edit to add; - Once the threads are combined I will "try" to answer/help DJPGold --- I say "try" because I am quite busy at the moment so just not sure if &/or how much time I can provide here

Kurt

 

[kurtak]

Hopefully anyone who has experience with Venturi fume hoods can help me out here I’m wondering if I would get away with shortening the air input tube from 1m to a couple hundred mm without a negative effect. My thinking is that it would decrease drag and improve the blower force closer to the output.

The red line marks roughly where the tube ends, and green marks the section I would like to cut.

Short answer - that is going to depend A LOT on the rest of your system set up ????

To be discussed once the two threads are combined

Kurt

 

[Yggdrasil]

First of DJPGold - could you please keep ALL of your questions concerning building a fume hood in ONE thread

Mods - could one of you please combine ether this thread with his other thread - or - the other thread with this one

the other thread is ------------

https://goldrefiningforum.com/threads/fume-hood-venturi.10979/page-7#post-338166
IMO - this one should be combined with the link above as the link above is already a longer & more in depth discussion about fume hoods which in turn takes other members to a more detailed discussion as we move forward in fume hood discussion to help answer DJPGold's questions

Edit to add; - Once the threads are combined I will "try" to answer/help DJPGold --- I say "try" because I am quite busy at the moment so just not sure if &/or how much time I can provide here

Kurt

Done now.
Frankly I did not see that it was a new thread.

 

[kurtak]

I think I’ll take this design from Kurtak and hope it works

That was my first build which though yes it did work it did not work near as well as I wanted so there where changes made to it to make it more effective

I am quite busy right now but will try to explain if/when I get time

Kurt

 

[DJPGold]

That was my first build which though yes it did work it did not work near as well as I wanted so there where changes made to it to make it more effective

I am quite busy right now but will try to explain if/when I get time

Kurt

No rush mate, you do what you’ve gotta do.
Apologies for creating a new thread, I didn’t want to “hijack” the previous but now I realise that’s sort of the whole point of a community forum

I’m keen to hear/see the improvements you made. My exhaust run has two 90° degree bends before the end of the run, atm I’ve got two 45° couplings so the bend is smoother, I haven’t yet finished the run. The blower that I used wasn’t strong enough for me to be happy so I’m getting a new one anyway, I will uploaded relevant pictures and videos later today

 

[DJPGold]

No rush mate, you do what you’ve gotta do.
Apologies for creating a new thread, I didn’t want to “hijack” the previous but now I realise that’s sort of the whole point of a community forum

I’m keen to hear/see the improvements you made. My exhaust run has two 90° degree bends before the end of the run, atm I’ve got two 45° couplings so the bend is smoother, I haven’t yet finished the run. The blower that I used wasn’t strong enough for me to be happy so I’m getting a new one anyway, I will uploaded relevant pictures and videos later today

Hopefully the blower I get will have enough power to work as well as I need. There’s a couple bends in this one and it’s not a long run before the bends either

 

[kaisernine]

Anyone doing this, especially in a residential home/basement ( either not recommended ) should probably have a second blower ready to go with some type of quick connect and alternative power source ( in the case power gets interrupted ) - just a friendly suggestion - this stuff can go south fast.

lots of people try to do refining safely in the now - without looking at the issues that can arise in the future - don't rush refining and it won't rush you.

 

[stoneware]

What do chimneys and smelter stacks have in common, neither require electricity to operate,

I believe a similar stack could be used to evacuate a fume hood.

The mound leading up to the smelter stack is a tunnel from a lower elevation.

 

[Yggdrasil]

What do chimneys and smelter stacks have in common, neither require electricity to operate,

I believe a similar stack could be used to evacuate a fume hood.

The mound leading up to the smelter stack is a tunnel from a lower elevation.

View attachment 53236

That depends entirely on temperature differences and height.
If you get the chimney interior hot enough over sufficient length, it will generate its own draft.

But it must be high enough and be kept at high enough temperature over the time it is used, which will cost energy of some kind.

So I believe that in real life applications of today, fans will probably be the easiest solution.

 

[stoneware]

That depends entirely on temperature differences and height.
If you get the chimney interior hot enough over sufficient length, it will generate its own draft.

But it must be high enough and be kept at high enough temperature over the time it is used, which will cost energy of some kind.

So I believe that in real life applications of today, fans will probably be the easiest solution.

Most people who own an older house with a fireplace will block them off from the room.

Even a fireplace without fire in the hearth will create its own draft from warm air in the room.

If you've ever been in an old mine shaft the air leaving the portal is very strong breeze.

Fume hoods create warm air, so why not go with natural convection.

 

[Yggdrasil]

Most people who own an older house with a fireplace will block them off from the room.

Even a fireplace without fire in the hearth will create its own draft from warm air in the room.

If you've ever been in an old mine shaft the air leaving the portal is very strong breeze.

Fume hoods create warm air, so why not go with natural convection.

First and foremost because it do not like obstacles and any scrubbing action will be an obstacle

 

[DJPGold]

Anyone doing this, especially in a residential home/basement ( either not recommended ) should probably have a second blower ready to go with some type of quick connect and alternative power source ( in the case power gets interrupted ) - just a friendly suggestion - this stuff can go south fast.

lots of people try to do refining safely in the now - without looking at the issues that can arise in the future - don't rush refining and it won't rush you.

I was thinking of either buying an identical blower that can be powered by a UPS, or make a quick connect port for my leaf blower that I can slap in

 

[Edlin]

No worries, thank you. I was hoping at the end of this thread there would be a conclusion on what works for the Venturi/eductor exhaust but yeah no luck. I think I’ll take this design from Kurtak and hope it works

Theoretically as long as the smaller diameter pipe extends past the wye it should still work

 

[dannlee]

They can tweak this design to pull a near-perfect vacuum (deafeningly loud!) or move high volumes of liquids with a small pump...

((Apologies I can't attribute the source of this image, kinda stolen off the NET a long time ago as a cheat sheet for my fume hood)