Hello everyone! I am curious if my idea has any traction, and would love to hear some feedback:

We currently have a Nederman dust collection system with a bag house that has 64 bag, that are all around 10" diameter (this could vary a little but you get the idea). We are currently entering the bag house to manually evacuate chips that have compacted into the bags about 2 times a week. I am feeling like this is excessive, and poses a huge loss in down time. My thought is that we could replace the floor of the bag house with a different manifold, and use a bag that has roughly 4x the diameter. So we would change to 16 bags that are roughly 40" in diameter. This would allow the chip pack to be heavy enough to overcome the friction of the bags. At least this is my thought. Any reason not to try this?

Also, has anyone reused bags after cleaning them? Is there some type of breathable spray out there that can give the bags some slickness, but allow them to function properly? Like a teflon spray?

Thanks in adavance!!

There should be no chips - shavings, large particle dust, etc - in the bags, period. The bags are the last stop in the system. They are to filter the air only as it returns to the shop. You should never have to shut down production to empty filter bags.

A proper, typical system will have a fan drawing shavings from the shop equipment to the cyclone where the larger particles drop out and the fines go on out the cyclone to the bags. Once the bags are about 10% full or so, then the bottom of the bag plenum should drop out or accommodate some way of cleaning or dropping the fine dust.

The shavings drop down into the neck of the cyclone and can then be rotary air locked or some way of moving that material where it is wanted.

We don't have a cyclone in this system, just a bag house and a rotary air lock. I am aware that big chips should not be going into the bags, but I don't know where else they can go? I think the input air (exhaust from the shop) exceeds the airlock's capacity. Attached is a picture...

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Do you have a shaker for the bag house?
We have had 2 bag house systems without a cyclone and no issues. But we always shake the bags often before starting.

Could be the air lock.

It looks as if there is a removal pipe going from the bottom of the baghouse to a dumpster? Is this pressurized?

Again, you have to maintain pressure in the system, and all activities have to happen within that pressure.

The fan is on one end, creating pressure, and the shavings are to fall into the hopper below the bags, and then taken off to a bin, a dumpster, a truck, etc. Pressure has to be maintained at least until after the hopper under the bags.

When all else fails, contact the makers and see what they can tell you.

The pipe going to the dump trailer doesn't come directly off the hopper, it is part of a separate blower system after the air lock. The big fan feeds chips and air into the lower hopper, at the bottom of the hopper is an air lock, and above our bag house. When the bags are empty (manually evacuated) the system pulls chips off all our machines nicely. But for some reason, the chips are being directed up into the bags, and packing them full. Then the suction at the machines slowly degrades, until we go up and manually shake the chips out of the bags. The system has a shaker (reverse air pulses through the bag house) on it that activates every 15 minutes while running. We also run the shaker cycle regularly through out the day when the system is not pulling air...

Hope that helps, I can't figure out why the chips are settling out of the exhaust air in the bag house and why they are packing into the bags. As far as pressure goes, I would think the bags packing would result in higher pressure in the bag house, which give more back pressure into the system resulting in poor suction from the machines...

Are the rubber paddles in the airlock in good shape or are they wore and letting air pass backwords through the air lock into the baghouse?

The last time we checked the paddles on the air lock they were in good shape, this problem has been persistent with good paddles...

Just doing a lot of thinking on this, and I am wondering if we are pushing too much CFM for the amount of cloth we have in the baghouse... Just thougths here

Are you running the exhaust blower aft of the rotary interlock constantly? We have same disa system except our rotary locks dump into a 40 yrd hopper. System runs 8 hrs a day without a problem. Regen fans cycle every 10 minutes to clean bags. Sounds like you are overloading hopper before blowing it into dump trailer.

My guess is that you are either overloading the system (airlock) with too much material too fast, or that you have a leak(s) that are allowing the chips to go unwanted places. Any/all small holes add up to large holes. Patch them all, then pressurize the baghouse and get a smoker to blow smoke in there to see if/where it comes out.

The blower system (moves the chips from the hopper to the contained trailers after the air lock) runs continuously while the dust collector is operating. Our system is set to re-gen every 15 minutes during operation.

I am thinking we have too much CFM going into the bag house which is allowing the air to rush through the hopper and into the bags without allowing the dust to settle out. I am thinking now maybe we need more cloth (a bag house addition) to reduce the pressure build up in the hopper. Another potential is to gear the air lock to spin quicker to help evacuate more material and potentially some of the pressure?

One question.... what machines are you running? and what amount of waste are you creating? Are these moulders, cnc, straight line rips? Our system runs 3 rotary airlocks without problems but it was sized for all the equipment we have.

We are running a 3-head 52" sander, a 2-head 42" planer/sander, 2 6-head moulders, and an automated rip saw...

I am sure you are correct that it should all be spec'd to the machines we are running, however it isn't in the budget to upgrade at the moment, so I was trying to see if there is another potential solution without a huge capital investment. I believe the CFM is adequate for the ducting/machines we have, as when the bags are freshly evacuated the collector pulls nicely...

Im betting that you are overloading your hopper with material. The single rotatory valve just cant handle that much material in my opinion. Also if you could move the collection fan further away from the hopper it would decrease the force of the material being moved allowing it not to be blown up into the bags. Our material fans are about 30 ft from the hopper.