A gallery of home built hoods and fume scrubbers _hood_

[4metals]

With a 10 cfm venturi and 3 tubes 48" long and 6" diameter you should achieve good fume scrubbing efficiency and the pH in the reservoir will be influenced by any inefficiency of the scrubbing. Keep the water as neutral as practical and put a pound or 2 of marble chips in the bottom of the reservoir to help buffer the pH.

The tube is because the venturi will spit all of the scrubbed air into the reservoir which includes a lot of bubbles. What can happen is the intake to the pump may suck in air if you do not redirect those bubbles. If that happens the pump will run in cavitation and stop pumping. The pipe simply re-directs the bubbles upward and the water flows out under the pipe which is not attached to the bottom, it just sits there. You can add a few holes towards the top in case your reservoir water level gets low but the concept is simply to redirect upward the air entrained by the venturi.

 

[geoffrod]

With a 10 cfm venturi and 3 tubes 36" long and 4" diameter you should achieve good fume scrubbing efficiency and the pH in the reservoir will be influenced by any inefficiency of the scrubbing. Keep the water as neutral as practical and put a pound or 2 of marble chips in the bottom of the reservoir to help buffer the pH.

The tube is because the venturi will spit all of the scrubbed air into the reservoir which includes a lot of bubbles. What can happen is the intake to the pump may suck in air if you do not redirect those bubbles. If that happens the pump will run in cavitation and stop pumping. The pipe simply re-directs the bubbles upward and the water flows out under the pipe which is not attached to the bottom, it just sits there. You can add a few holes towards the top in case your reservoir water level gets low but the concept is simply to redirect upward the air entrained by the venturi.

Ah got it, thanks for the detailed explanation.
so marble chips you mean calcium carbonate?

 

[4metals]

Yes here in the states garden centers sell bags of chipped marble, small stones crushed into gravel size, for use in gardens or ponds. Marble is calcium carbonate and the larger pebble size will slow any dissolution.

 

[geoffrod]

Yes here in the states garden centers sell bags of chipped marble, small stones crushed into gravel size, for use in gardens or ponds. Marble is calcium carbonate and the larger pebble size will slow any dissolution.

I couldnt get marble chips, but i found the pet place down the road is using decomposing coral for that same purpose in his fish tanks. so i got some of it

 

[4metals]

I couldnt get marble chips, but i found the pet place down the road is using decomposing coral for that same purpose in his fish tanks. so i got some of it

New South Wales, Australia, coral makes sense.