Sealing HFDC leaks

[Rich P]

I just finished reworking my HFDC to a Wynn 35A canister, a Thien baffle and the "stovepipe" replacement for the 5" hose. In watching for leaks in the new setup I noticed a bunch in the fan housing which I guess had been there all the time. They were coming from the seam where the two housing halves are joined and also from the connection where the outlet flange attaches to the fan housing and where the inlet connects to the filter/bag ring.

I am curious if others have had similar leaks and if so what was done to address them. If this is something common then it probably should become standard procedure for these units.

For now, I have patched mine with RTV silicone adhesive caulk and it seems to be holding.

[JR]

I haven't noticed any such problems, but I'll give it a close inspection and report back.

JR

[Hellrazor]

The answer is obvious...


HF Duct Tape

[dbhost]

I have a 20% off coupon, AND a flyer that is listing the price at $179.00.... BUT there isn't a single one of these dust collectors to be found in the Houston area, and hasn't been for several months... Idiots...

[Rich P]

If you have tried HF sandpaper you would know that HF duct tape is best used for gift wrapping.... Plus, after doing the tape job on 5" heater duct (stovepipe...not!) it starts to remind me of a 3rd world country solution. I can't believe I'm the only one to notice this, especially with my shop bifocals always dusted with the sub micron stuff that has been spewing out from these leaks, probably since day one of putting this POS into operation. Start with the lowest HF price you can find, factor in the bucks and effort and time you need to put out to make it sort of work and I'm having a had time finding the ROI. Maybe others have a better experience. Only positive thing I can see is it is priced where it will entice some of us (like me) to explore this dust problem.

[tjmac44]

My Harbor Junk DC with Wynn Cannister leaks where the metal band holds the lower plastic bag. It is the fine dust that gets out and does show up nicely against the venerable green. I have to duct tape the entire bag above the metal band to stop the leak.

[Rich P]

I seem to have solved that one by putting weather stripping around the bottom edge of the ring. Jet bags are a bit too large so you need to be careful of folding the excess so it does not leak. Wynn says you need to stretch their bags so presumably this would not be a problem.

However as Eastwood says in Gran Torino, "Take these three items, some WD-40, a vice grip, and a roll of duct tape. Any man worth his salt can fix almost any problem with this stuff alone."

[LCHIEN]

My HFDC doesn't have any leaks between the impellor and the ring.
The PSI bags I use are thick (7 mil?) and just a bit oversize so there's a few folds in the bag under the clamp and there's some fine leaks there. Doesn't seem to be too bad, I can see the trail but during operation I don't see any dust flying, if measured in CFM it must be miniscule.
A thinner bag would have smalller leaks at the folds, I presume.

[rjwaldren]

I went around the seams and bolt holes on my green HF portable unit with RTV, it did a fantastic job.

[master53yoda]

Leaks on the positive pressure side of the DC don't reduce air flow only those on the negative pressure side of the fan reduce air flow. Leaks on the positive pressure side of the fan do put unfiltered air into the room.

The best material to seal duct work is shown in the pictures below. This is used in commercial duct systems and won't peal off after time as the RTV and tape will.

The duct seal is available from Lowes for about $12.00 per bucket which should do any duct system in a residential shop. It is a gray paste and is put on with a paint brush

[LCHIEN]

I didn't mean to say the CFM leaking was affecting the air flow from the tools.
My point was that if I have 500 or so CFM coming in carrying homogenous dust a small fraction of 1 CFM leaking back to the room is maybe .1% of the air flow and the same fraction of the dust assuming its still homogenous so I'm not too worried about it. I could only wish I capture 99.9% of the dust at the source.

[Rich P]

Art, the gray goop is good to know about when I get ready to run duct work. For now the unit must be mobile so I'm stuck with hoses.

My concern about the (positive pressure side) leaks was not so much about CFM loss but about having dust blown back into the room. Probably not too much to worry about but since I was on a "leak elimination mission" they had to get addressed.

Like RJ I used RTV and worked it into the gaps in the seams. After letting it cure overnight all leaks were gone today, so I'm satisfied for now. Not sure how long it will last but the only portion that has to stay in place is the bit filling the gaps in the seams. If the RTV fails in the future I'll post that on this thread (if I remember to).

I agree with Loring that there is probably more dust uncaptured at the tool end on some machines than what was escaping from the DC unit itself.

[dbhost]

My Harbor Junk DC with Wynn Cannister leaks where the metal band holds the lower plastic bag. It is the fine dust that gets out and does show up nicely against the venerable green. I have to duct tape the entire bag above the metal band to stop the leak.

If you read the Wood Magazine test review of Dust Collectors under $400.00, you would know that all of them short of the Delta 50-760 leak like a sieve at the point where the bags meet the inlet ring. They suggest sealing this with stick on weatherstripping from the home center. An easy, cheap fix that is NOT unique to the Central Machinery unit, but rather just part of the nature of the design...

[Relative]

If you read the Wood Magazine test review of Dust Collectors under $400.00, you would know that all of them short of the Delta 50-760 leak like a sieve at the point where the bags meet the inlet ring. They suggest sealing this with stick on weatherstripping from the home center. An easy, cheap fix that is NOT unique to the Central Machinery unit, but rather just part of the nature of the design...

I just went outside to the compartment where my HF DC is located, and using a incense stick, ran it around the joints where the inlet ring and bags meet. The air flow there was almost nonexistent. About 3 days ago, I emptied the bottom bag, turned it inside out and beat the heck out of it to remove anything stuck to it. Did the same with the top bag.

I suspect that leaks at this point are due to primarily two things, the bags get clogged from fine dust and weren't cleaned enough the last time the unit was emptied and now pressure is too great for the seal. Second possibility of a problem is when a finer bag has been put in place of the original design bag - kind of like installing a bag already partially clogged. This may make for less fine dust escape, but also decreases the air flow unless some other point allows escape of the air flow.

I've wondered if users of the Thien baffle have started to get complacent because the amount of stuff that gets past the Thien is almost nil and just the fine stuff hits the bags. If they are just dumping the stuff the baffle catches and never open up those bags, they will wind up with a very inefficient air flow - unless there are leaks after the motor to allow the built-up pressure to escape - which will also put fine into the area.

To me, the best setup to avoid breathing the fine is to put the DC somewhere outside - including any baffle arrangement. Put a manifold on the wall punched through to the outside and have multiple ports inside to go various directions, left, right, up and over, and down to a sweep port.

2 cents

Mike

[DaveStL]

I used rope caulk to seal the Wynn canister to the housing of a 50-760 because the gasket supplied w/ the cartridge didn't match up. I probably should have asked Wynn for a gasket that covers a larger area of the canister, but this work pretty well.

Dave