wide belt sander dust collection

[sthole]

good afternoon!
we have a 37" wide belt sander that we pass stainless steel tubing through. the process leaves us with dust and small metal bits. we are having trouble picking both of those up with our dust collection system.
we have a new 2000 cfm dust collector (bag house) w/ high static option, and a 10" line to the drop and then an 8" drop to the machine. we have checked the bag house to ensure that it is running properly and the fan is spinning in the correct direction.
the 10" goes onto another machine but we close off that gate when using the wide belt.
we are not getting even 1/10 of the dust/metal bits, they end up on the floor.
any ideas?
what percentage of dust/metal bits should we expect to pick up.
thanks......................

[vk4]

You are trying to pick up a much heavier particle , plus cutting the 10" off you are effectively strangling the dust extractor.

If possible connect both pick-up o the wide belt machine, this will give the extractor a better chance to pick up the metal dust.

I would advise that you clean out the sander each day regardless , as the metal dust will be fatal to bearings and unsealed motors.

jeff

[ian]

I don't currently have access to my calculation sheets, but places I would be looking are:
air velocity in the ducting -- the air velocity from 2000 cuf/m through an 8in and 10 in duct is almost certainly too low to carry the metal particrles away.
Pressure loss -- does your ducting use 90º ºbends or T-junctions? both are bad if you want efficient suction
How much of the 37in width in the sander is empty of material being sanded?

Fire risk if you're mixing metal and wood dust in the same system

[BobL]

I don't currently have access to my calculation sheets, but places I would be looking are:
air velocity in the ducting -- the air velocity from 2000 cuf/m through an 8in and 10 in duct is almost certainly too low to carry the metal particrles away.

Even before the metal/dust gets into the ducting the cross sectional area of the pick up port(s) is what is critical to being able to pick up the metal.

If the pick up port is just a 1" wide slot and the sander is 37" wide, that is 37 sq inches or ~1/4 sqft of pick up port.
This means the air speed at the pick up will be nominally 8000 fpm which is OK for wood and metal dust, but will struggle with metal pieces. My guess is the dust extraction is at just located at one point along the 37" belt width, if so there is no way that the air flow can pick up dust more than a few inches either side of the duct. Can you post a picture of the pick up duct/slot?

If the extractor is a true 2000 cfm then nside the 8" duct the the air speed is nominally 5700 fpm and inside the 10" duct it will be 3600 fpm, as Ian says these is low even for wood and will not carry metal dust let alone chips.

What brand of dust extractor is it ? Can you post a picture of it especially around the impeller intake area. If the impeller intake is not size matched to the 10" ducting, my guess is it will be throttled. If it is a budget level dust extractor with the bags on my guess is it will not be delivering anywhere near 2000 cfm, more like 1000 cfm.