First Successful Watertrap Failure

So after quite a few hours of milling, my homemade water trap has proven to be pretty effective. The hepa filter doesn’t seem to have really picked up any notable amount of dust, while the water trap tends to have quite a bit of mess in the bottom of it.

Well just a bit ago I was grinding out some birch plywood, and it was a fairly small job, so I didn’t think much of it, turned on my shopvac and let it run, until I heard a large pop. Apparently, my itty bitty shopvac, which often doesn’t pick up anything but the smallest chips, decided to pick up all the ripped out grain that plywood is so famous for, which filled the bottom of the bucket all the way up to the intake port of the trap, and collapsed the bucket.

No real damage done, I just had to pop back out the bucket, and I’ll need to reseal one of the pipes. I’ll probably shorten the intake pipe a bit, and maybe add only a little water next time I’m milling plywood, since it’s all picked up by the splinters anyway.

Also since I only had a couple minutes left on the plywood project when the bucket collapsed, I just let it run without the shopvac on, since I had no good way to connect it directly to the nomad. I could easily tell the difference in air quality, which shouldn’t be surprising, but it still nice to know it’s working.

Overall I feel it has been a quite successful 14 dollars spent.

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Collapsing a plastic bucket is actually pretty easy. Nicely done! :smiling_imp:

This can happen with a plastic container for a cyclone as well… but it’s a bit harder to get this to happen.

mark

is a water trap more effective than a cyclone/vortex approach re dust collection?

is a water trap more effective than a cyclone/vortex approach re dust collection?

Water traps were used before we had cyclones. They died out for most uses many years ago. They can be pretty efficient, especially if they have misting involved.

@imp and I discussed this and for the money - and the parts he had lying around - this was the best fit for his needs. The key is to separate as many particles as possible before they hit the expensive HEPA filter. The HEPA filter is the true safety device for air (exhausted into the room with people)… but we don’t need to makes its job difficult!

I prefer cyclones - they are known to work and work well - but the design @imp used is pretty good.

mark

@imp, please post some pictures of your water trap. Any design and construction notes would be great!

Thanks!

mark

okay… is a water trap more effective than a cyclone/vortex approach re dust collection?

okay… is a water trap more effective than a cyclone/vortex approach re dust collection?

It’s not a simple answer. In general, no… but pretty close. If the water trap uses misting, it can equal or exceed a cyclone (small like we use).

Ultimately, one still needs a HEPA filter to protect themselves. A cyclone or water trap is about reducing the rate that particles “fill up” the filter. Since HEPA filters are often expensive, we want a cheap way to cut the cost, hence the “dust separator” ahead of the “dust collector”.

mark

so if a water trap can equal or exceed a cyclone via misting, how is it — “in general” — a “no”? not picking at nits here, but your responses are rather confusing.

perhaps someone with more experience will answer me.

so if a water trap can equal or exceed a cyclone via misting, how is it — “in general” — a “no”? not picking at nits here, but your responses are rather confusing.

I’m sorry you have not understood. Let’s try this again.

okay… is a water trap more effective than a cyclone/vortex approach re dust collection?

A water trap’s efficiency depends on its design. A simple water trap will not exceed the efficiency of cyclone. A water trap that includes misting, agitation, and other complex issue that go into water trap design can equal or exceed the efficiency of a cyclone.

Few, if any, non commercial water trap users will be willing or able to design a water trap that meets or exceeds a cyclone for efficiency since the design and construction issues are complex.

Simple water traps are “pretty good” but do not exceed the efficiency of a cyclone.

Water traps are cool! A conversation piece for sure as they aren’t seem much today. Definitely simple to construct, cheaper than a cyclone (not counting ones time), and for a simple one pretty good.

Water traps were used before cyclones became popular. The simplicity of the cyclone coupled with not having to deal with water lead to them virtually disappearing from use. The “wet mess” is quite a challenge to deal with on a commercial scale - heavy and yucky.

The “wet mess” that comes out of a water trap is considered repulsive by some. YMMV.

A cyclone, water trap, Thien or other technology function as a “dust separator”, removing a large percentage of the “dust” before it enters a “dust collector” (vacuum). This reduces the stress/mess on the “dust collector” and, should it have a filter, extends the life of the filter (since far fewer particles get to it).

As I’ve written about elsewhere, a HEPA filter (rated at 0.3 micron) is necessary when the air exhausted from the “dust collector” is “inside” - where humans are. This is the only way to ensure that one is reaching safe levels of dust “inside”.

If the exhaust can be dumped “outside” and one can ensure that the air doesn’t easily return to the work area, no HEPA filter is necessary - but a “dust separator” is necessary. We don’t dump bulk dust outside - this is safety hazard. Dumping air outside has a downside that may prevent its use for some - noise. The tubing sends quite a bit of noise outside… perhaps upsetting a neighbor.

When dumping air “outside” - after going through a “dust separator” - one doesn’t need a HEPA filter but it’s a good idea to have a simple filter. A 5 micron cloth filter bag is an inexpensive and acceptable solution - they can be washed and reused! The minimal filter “outside” prevents “snow” from accumulating outside the exhaust port - because some particles of all sizes do get through and over time they settle around the exhaust port.

Cyclone “dust separators” are the industry recognized, well tested, and well understood method of “dust separating” on the small to medium scale. There are other technologies used on the industrial scale when dealing with massive amounts of dust… these are not applicable to us.

One alternative to the cyclone and water trap that is applicable is the Thien dust separator. The cyclone element is somewhat difficult for most people to build (difficult to construct shape; the parameters to be efficient are complex); the Thien is easy and inexpensive to build - and no water. The downside of a Thien is that it is generally not as efficient as a cyclone and commercial cyclones have become very accessible price wise - we see them being use less and less now-a-days.

A Thien and a water trap are going to approximately the same efficiency when properly designed - the Thien slightly better compared to simple water traps. Between the two - not having a cyclone - I would go with the Thien as no water and no “wet mess”. YMMV.

Since the “dust separator” is technically optional when the exhaust air is “inside” - the HEPA filter is the ultimate safety device for air quality - the efficiency of the “dust separator” is important (lower means the filters are “used up” faster) but not critical.

@imp had a discussion with me about using a water trap, including the design of what he was doing, and he understands the tradeoff he is making - low budget and not necessarily as efficient as a cyclone - but not, by any means, a bad thing to do. Anything (“dust separator wise”) is better than nothing!

As with all “dust separation” and “dust collection”, the “dust and particles” in containers and filters are dangerous! They should be handled outside with the human upwind of the stuff or wearing a 0.3 micron HEPA filter mask. Try, VERY HARD not get exposed to the stuff! Some people vacuum their clothes and wash their hands are emptying containers and changing filters.
mark

P.S.

There is one commercial vacuum cleaner on the market that uses a water trap - Rainbow. The design dates from the 1929. I used one for many years.

The Rainbow is split into two chambers. The upper chamber is the true vacuum. It pulls the air in. The air is sent to a separate chamber, the water trap. The upper and lower chambers each have an impeller - run by a single electric motor. The impeller in the upper chamber is nothing to write about - it pulls air. The lower chamber impeller is… amazing. It was patented at one point; I don’t know the current state.

The lower chamber impeller - the water trap - is design to literally induce a tornado and to do something very cool. The impeller/tornado sucks up water and breaks the water stream into tiny droplets and water vapor. The air coming out of the upper chamber is blown through the suspended water and is exhausted. The water droplet and vapor catch the particles and they fall to the water below. Excellent filtration. No HEPA filter.

Yes, one has the “wet mess” to clean up when you’re done but the filtering is excellent… and your home vacuum is a wet/dry vac! They are expensive but last for decades because the design is so simple.

Mark, great information. Could a water trap be used for filtering exhaust/fumes from a laser on an SO3? Been thinking of trying a used Rainbow, but don’t want to listen to the screaming motor.

Mark, great information. Could a water trap be used for filtering exhaust/fumes from a laser on an SO3? Been thinking of trying a used Rainbow, but don’t want to listen to the screaming motor.

As I pointed out, a water trap is fine for a dust separator, not a filter for safe air handling when the exhaust are from the “dust collector” is dumped “inside” (at least on the scale we have access to).

When dealing with a laser, new issues are introduced - chemical reactions. Now we have nasty compounds generated (carcinogens, teratogens, and gases (even cyanide)) as chemically reactive particles, molecules, vapor, and gas. Particles from 100 microns down to molecular size are generated.

The technologies we’ve been discussing here are for particles 0.3 micron and above. Some of the stuff coming off a laser will get caught (by CNC safe air handling designs) but the molecular and gaseous stuff will get through.

The last thing I want exhausting “inside” is the output of a laser cutter. CNC “dust” from friable materials is dangerous; laser cutter “dust and gas” are more toxic and more dangerous.

The only safe method I know - on a small scale and within our budgets - is to use the exhaust “outside” method. Yes, it should also go through a filter of some kind, preferably better than the 5 micron one I mentioned above… but that can be discussed. The key is get it away from you as fast as you can and don’t let it come back! Dilute it as fast as possible to safe levels.

mark

There was a design worked up and published on the Sawmill Creek Forums a while back for a fairly inexpensive air cleaner system for lasers which used activated charcoal for a filter.

There was a design worked up and published on the Sawmill Creek Forums a while back for a fairly inexpensive air cleaner system for lasers which used activated charcoal for a filter.

However, keep in mind that activated charcoal has limited absorption ability and has to be replaced. Even with a filter I wouldn’t exhaust the output air back “inside”. It’s all about managing risks and how much one trusts things. YMMV.

Hand made designs may be just as good as commercial stuff. Unless it is tested and proven to have the necessary characteristics I wouldn’t trust a design no matter how well intentioned and designed it is… and dumping air outside usually isn’t hard and is ensured to be safe.

mark

I’m primarily looking for a way to reduce the odors when I exhaust it outside.

Hadn’t considered exhausting it inside, should have clarified that earlier. Most of my work will be engraving wood.

I’m primarily looking for a way to reduce the odors when I exhaust it outside.

Does that mean the odors are coming back “inside” or “outside” stinks?

If you’re already vending “outside” and “outside” stinks, using a filter like the one @WillAdams mentioned would help - activated carbon will eat odors quite well - until it has depleted it’s holding abilities.

Any centrical dust separation technology (e.g. cyclone, Thien, etc.) isn’t designed to remove gases or molecular level particles. None-the-less, it will help with the “stink” somewhat - many of the particles are chemically active (hence the smell) and trapping them will help.

A water trap will do better - water is likely to grab some gases too - but I cannot say how well it will work… too many unknowns. An activated carbon filter will do very well indeed… it’s what they are designed for.

mark

There is a good possibility the odors could make into another part of the house once we open the Windows going into summer, looking for ways to mitigate the issue before it becomes problematic.

Would it be possible to use a water trap and carbon filter?

There is a good possibility the odors could make into another part of the house once we open the Windows going into summer, looking for ways to mitigate the issue before it becomes problematic.

That violates the requirement that the air dumped “outside” not easily come “inside”… and yes I understand your situation better now.

Would it be possible to use a water trap and carbon filter?

Certainly… but there is a downside - vacuum. Each element added to a piping chain adds “friction” and “resistance” to the air flow. The requirements for the vacuum to ensure that the output pressure is sufficient to push the air effectively through the water trap and carbon filter increase by quite a bit. I can’t give specifics without more data. I can say that the tubing size should be 2.5" minimum and preferably 4" - we need to move air!

Is it possible to exhaust “up”, outside the window? Think a smoke stack. One of the reasons to go up when releasing exhaust is that air speeds increase and there is more time for dilution before it gets to the ground. Even 6-10 feet makes a bit difference.

mark