Thread: Advice needed for large rip saw

20m of 8" ducting back to the factory's DC system will cost a lot less than a dedicated unit needed for this machine and it won't be that restrictive.
If you want belt and braces go for 9" and you can forget about the effect of duct restriction over 20m
The benefit of venting it outside will well outweigh the maintenance nuisance, space loss, noise, and ultimately all the fine dust that will inevitable come out of a DC or cyclone.

RE: 3HP Do you mean you are limited to a 10A GPO or a 15A GPO or a 3HP DC?
A 3HP DC will not deliver enough air to cope with 8" ducting as the air speed will be too low and sawdust may fall out of suspension.
A 3HP DC is limited to 6" ducting and through this it will draw ~1200 CFM, splitting this via a 6" to the cabinet and a 4" to the guard will give you about 350 cfm to the guard and 850 cfm to the cabinet - this is a pretty standard way of doing this.
If you have a 15A single phase supply you could use a Clearvue with a 3Phase 4HP motor and use a VFD to convert single phase to 3Phase.
If you want the 8" capability you will need the bigger unit.

But if it was me I would invest in 9" ducting and get the dust outside.

Thanks for the reply Bob. The saw is under a mezzanine level so the ducting would need at least 4 90-degree bends to connect and our system hasn't got enough extra capacity to run another 9" (or 8", for that matter) without having to close other branches, so it's not really a convenient or practical solution. We'd also need to hire a cherry picker to install it all and cut another hole in the wall to connect before the first reducer section. For the record: I do like the idea, but it was never going to happen.

We've decided to move an unused 3ph auto-on switch to the rip saw and get a generic 5hp dusty with cartridge filters. Not the best solution, but it's as good as it'll get. Is it possible to get sub-micron cartridge filters, or it 1 micron the limit?

Originally Posted by elanjacobs

Is it possible to get sub-micron cartridge filters, or it 1 micron the limit?

The cleavue people sell sub micron filters but the profile is in a 6' or 8 " diam by x ft long "sock" and does not suit the generic type DCs with filters/bags. You'd have to put the DC in an enclosure and then fit the sub micron filters to the outside of the box. This is not such a dumb idea as it would then handle the usual leaks etc that these DCs exhibit.

FWIW 90º bends in 9" ducting lose about 0.1" of WC compared to 0.22" for 6" ducting
20m of 9" ducting will lose about 1" of WC compared to 2.6" for 6" diam ducting
i.e. not worth worrying about, BUT 9" fittings will of course cost a BOMB but thats another story.

Originally Posted by BobL

9" fittings will of course cost a BOMB but thats another story.

And there's the problem

I'll suggest the box and CV filter, but not likely to happen - especially at $400.

Thanks again

Originally Posted by elanjacobs

Hi all,

Recently got a new rip saw at work (pic below) and trying to run the generic 2hp dusty on it is just a joke, so we need to upgrade. The main port is 6" direct to the blade housing (same as a panel saw) and we plan to cut the back corner (with its wimpy 2" port) off the overhead guard and get a folded sheet metal transition to a 4" port.

Whatever we get will sit right next to the saw, so ducting losses will be minimal and it WILL be vented back into the factory (not negotiable, the nearest external wall is 20m away and hooking into the main extraction system isn't practical). We're leaning towards a cyclone, but will settle for a conventional bag unit with cartridge filters if we have to. The unit needs an 8" inlet (to get a 6" and a 4") and needs to be single phase (max 3hp) as we have an auto-on power point.

Also, I know about the ClearVue MAX; it'll cost about $4k with filters and the budget is $2k (might be able to push the boss an extra $500).

Thanks in advance.

image.jpg

As you may know I am biased and declare my interest.

However your boss needs to be aware of the enormously restricted amount of dust allowed in a work environment. Most workplaces do not come close to what is required and few people get caught out. But what about when a worker gets a chest infection and makes a claim. The fines alone make the proper equipment sound cheap.

In layman's terms the requirement was explained to me by an inspector as being equated to no more than an egg cup full of airborne dust in a double garage sized unit.

It is not the dust you can see that kills you!

After further discussion (read:nagging), it has been decided that we will hook into the main system with a 4" overhead and 6" below with a blast gate. We're also getting 4 used (long story, but it involves a regular client who has them lying around) air purifiers to hang at dust hot-spots for whatever good they do.

Turns out that we're almost at the limit of power supply to the factory and another dust extractor with enough grunt for what we need will draw more than we have.

Thanks again to all

Originally Posted by elanjacobs

After further discussion (read:nagging), it has been decided that we will hook into the main system with a 4" overhead and 6" below with a blast gate. We're also getting 4 used (long story, but it involves a regular client who has them lying around) air purifiers to hang at dust hot-spots for whatever good they do.

Turns out that we're almost at the limit of power supply to the factory and another dust extractor with enough grunt for what we need will draw more than we have.

In terms of power, 4 air purifiers would just about equal a big DC.

I reckon you are better off just opening all gate valves and running the DC for some time after the last dust making activity than using air purifiers.

Originally Posted by BobL

In terms of power, 4 air purifiers would just about equal a big DC.

I reckon you are better off just opening all gate valves and running the DC for some time after the last dust making activity than using air purifiers.

The purifiers are more for the work benches (especially for under the mezzanine) but we'll also have one above the linisher as the extraction there isn't as good as is should be (that's my next project). I guess we'll see how we go with power.

The DC ports are all fairly well shrouded, will they pick up much in the way of 'free' air?

I guess it's hard to give/get advice without seeing the setup

Originally Posted by elanjacobs

The purifiers are more for the work benches (especially for under the mezzanine) but we'll also have one above the linisher as the extraction there isn't as good as is should be (that's my next project). I guess we'll see how we go with power.

The DC ports are all fairly well shrouded, will they pick up much in the way of 'free' air?

I guess it's hard to give/get advice without seeing the setup

Yep it makes such a difference seeing what is next to what.