Just upgraded from a shop vac, to a small “Ozito” dust extractor. It’s 1100 watts, 50 litre capacity with a 100mm flexible hose. What I’m thinking of doing is making a “Hood” from gal sheet approximately 3 feet long by 1 1/2 feet wide and either mounting this from the ceiling of my bay (above head height), or on one of the walls at about knee height to catch the dust as it falls. Does anyone have any experiences with either of these set ups? Do ya reckin it’ll work or will it suck (pardon the pun!)
Any advice would be appreciated.
BTW, I shape, sand and glass in the same room.
Checked the archives, but not a lot there on this topic.
It won’t work as you are imagining. You would need at 5 to 10 times more CFM before you would see any significant air flow in the whole room. Your shop vac’s CFM is just a couple times more then what a comon bathroom fan generates and while they can move the bad air from a small room their Velocity of air flow wouldn’t be capable of moving sanding dust.
Your shop vac is designed to move dust only within a few inches of the end of the hose. If you try to flair the end of that hose out to the size of hood you are describing, the velocity of the air flow will drop down to the point where it will be imperceptible at the outer edges of the hood, let alone the room
Study up on what these terms mean and how they interact with each other. CFM=Volume, Static Pressure and Velocity. Then you will understand the kind of CFM and SP you would need to create the amount of Velocity you want to move it at.
A steady Volume of air pulled through a smaller hose will cause an increase in the Velocity of the air flow to maintain the same Volume as long as the fan and motor can handle the increase in Static Pressure that the smaller ducting and filters creates. This example is like your shop Vac. But increase the diameter of the hose and the Velocity will rapidly drop off and it won’t be able to carry the dust particles.
Same Volume moved through a huge duct, like a shaping room, will so radically reduce the Velocity of the air flow that you won’t even recognize any air movement.
Moving the large Volume of air in a sanding room at a high enough Velocity to carry the dust particles away from the worker and from one end of the room to the exhaust duct at the other, requires a super efficient fan driven with a substantial amount of horsepower to create the High Static Pressures required to pull the air at high Velocities and high Volumes. Let alone then, that same Volume through collectors or filters.
Depending on how much space you have there are solutions to moving the dust though. I am sure you will get a ton of suggestions here.
Directly behind the Jet system is an exhaust fan that takes the filtered/stale air outside.
So all the air constantly flows across the room, gets filtered, and goes outside. I never seem to have any problems with ambient dust floating around and creating a fog.