5" flex pipe vs. 4" PVC

[Carlos]

I have the HF collector and I'm moving the shop around, building new DC plumbing. I just can't seem to locate any 5" PVC pipe. I do have an easy source for 5" flex tubing, standard DC stuff. Cost is actually slightly less than what I think PVC will sell for (considering the cost of 4" PVC). I have found 6" but the price is just ridiculous ($35-45 per fitting, didn't even bother getting the price of the pipe itself).

So I wonder if I'd be better off just using the 5" flex, which makes the plumbing easy. It appears to be fairly smooth inside, though not quite as smooth as the PVC. However since it's quite a bit larger, it seems like that would make up for it.

Thoughts?

[SARGE..g-47]

"Thoughts....

A man has to do what a man has to do...

I am not familar with the HF DC.. but I would say that it depends on how far you are trying to reach out and how many ports. I have seen a tendency IMO for people with 1 1/2 HP - 2 HP DC to run elaborate systems that probably should be powered with no less than 5 HP. It certainly looks good but they miss the point of resistance fighting small, under-powered impellors.. too many ports with too many reductions.

So... what is the rest of your plan?

I will add at this point that I run a 2 1/2 HP Penn State Tempest with a 14" impellor. I intentionally placed the cyclone in a position that the 4 major machines I connect to (18" BS.. 20" planer.. 8" jointer.. Uni-saw used strickly for ripping) have it boxed in.

I use a short amount of 6" PVC over-head coming out of the machine, but the remaining 16' is clear flex pipe with copper wire spiraled through-out to give me ground connection from cyclone to machine. I enlarged the ports on all machines to 6", so I have an aproximate run of no more than 25' from cyclone to machine cluster. The way they are placed in proximity to the Clone, I have to curl the flex pipe on the floor for a couple of them as it is much shorter distance than the 16' of flex coming off about 8' of PVC allows.

I like the Clear Flex hose as I can see chips moving through and can detect any dust pocket build-ups or chip clogs. The wire inside does take away some cfm as the inside of the flex is not baby-butt smooth as PVC. But.. I have the power to overcome that with 6" pipe from cyclone to machine with no down-size when you get to the destination as each machine is hooked up directly from cyclone to machine one at a time as required.

In closing, I had a gentleman drop by to buy a Lie-Nielson DT saw the other day. He saw my flex hose and "scorned" that I was losing too much cfm by using pipe that was not smooth inside. I turned on my cyclone and placed the end of my flex pipe run to the seat of his pants and told him to remove it with the machine on. He ask me to turn it off about 30 seconds latter.

After the apology... he went home with his new LN Dove-tail saw and a new attitude about "what will and what won't" that came from a source other than "all" he had read to qualify him as a dust collection Guru.

So.. IMO, depends on how far.. how many ports to serve.. how many reductions.. how many twist and turns along the way.. how much power.. how much cfm created on the DC end.. how large the impellor.. and what shape the impellor.

And you thought you were asking a simple question..

BTW Carlos.. Penn State has 5" black flex.. 5" clear flex.. and 5" clear re-enforced like the 6" I use.. but is not as flexy with that spriral wire running through it continously.

Hope some of the above rambling helps.. and good luck!

[JR]

Carlos, didn't you used to have a sort of octopus thing hanging from the ceiling? IIRC, it was a bunch of flex hoses going into a plenum of some type.

What happened to that? Did it work, not work, needs improvement, what?

JR

[windmill]

I have the HF DC as well. I would not use 6" pipe with it, it simply doesn't have the power for that. I used 4" S&D PVC (cheap and easy), but 5" should work as well. It's pushing it in terms of velocity though. PVC does not come in 5", only 4" and 6".

I would not use 5" flex tubing. The amount of resistance you get from any kind of flexible tube/ hose (whether metal or plastic) is 10x compared to a smooth pipe. Look at standard HVAC pipes first.

[dkhoward]

I have the HF DC in my shop connected to a chip collector based on a 35gallon cola syrup barrel and the rockler cyclone top with some modifications inside. My shop is plumbed to the blast gates with 4" S&D and then to the tools with flex.

I like the S&D because:
1. its cheap
2. I can get long diameter fittings, cheap
3. It is smooth inside and its cheap
4. It is lighter in weight than PVC and its cheap

I have not had any issues with power, suction or carrying ability. I really have not had any issues with static build up, even when using it with my planer or the jointer which produce a lot of chips which genearlly generate a lot of static.

[Carlos]

Carlos, didn't you used to have a sort of octopus thing hanging from the ceiling? IIRC, it was a bunch of flex hoses going into a plenum of some type.

Well, you haven't lost your memory! Yes, I still have that, for the purpose of providing suction to the tops of tools that use 2.5" and are best reached from above (SCMS, table saw guard, drill press, etc). It works great since I only use one at a time (actually the table saw guard is "always on" but has so much restriction due to its size that you can't tell).

I turned on my cyclone and placed the end of my flex pipe run to the seat of his pants and told him to remove it with the machine on.

Well, I have to put my scientific cap on and say that your test was not one of CFM, but of total suction. You could have done the same with a 1" tube probably. You gave me a lot of good info and useful thoughts, thanks for taking the time to type all that out. I might go with 6" flex up to the ceiling to the first major split, then 5" to the tools, and 4/2.5" as needed there.

Here's a view of the shop layout, with just the beginnings of the DC ducting drawn in. The space is a three-car garage, with a two-car area for most of it. The bandsaw will be far off into the lower left corner however, at the far side of the single-car area.

[os1kne]

Sorry, I can't help with the DC questions - but those drawings of your shop are great!! Nice work!

[ryan.s]

I like the S&D because:
1. its cheap
2. I can get long diameter fittings, cheap
3. It is smooth inside and its cheap
4. It is lighter in weight than PVC and its cheap

Dennis, I'm not getting a clear picture why you like the S&D pipes, would you mind explaining it again?

Carlos, I don't quote me on this but I recall reading somewhere that it's more efficient to use 4" smooth walled pipes versus 5" flex hose. The sp loss wasn't enough to overcome the increase in volume between the 4 and 5 inches. I'm still looking for where I saw this which will also tell me what the setup was, once I find out I'll post again.

[LarryG]

My DC system is powered by the same HF 2HP DC you have, and plumbed with 4" S&D pipe. All branch-line blast gates are located as near the main trunk as possible. The shortest hard-pipe run, at the band saw, is about five feet (the jointer branch is about the same); the longest, at the OS/B sander, is almost thirty. In between are various other distances for all the other tools. The final connections are all made with either a 4" or 2-1/2" hose, the lengths of which vary, but none exceeds about four feet.

The result is that I get very good chip and coarse-dust collection*** at all stations, regardless of distance. My seat-of-pants analysis is that hard pipe is so much smoother than flex hose, it almost doesn't matter how long the runs are or how many bends they contain -- within reason, obviously. I concur with the others that even though the 4" S&D might theoretically be an inch smaller than optimum, it'll still be leagues better than 5" hose. I know dust collection hose feels fairly smooth on the inside, but aerodynamically, it's a disaster. Those ribs will create all manner of turbulence, which kills the performance of the system.

(*** I think you're already aware, from the other recent threads as well as the results of the WOOD Magazine test, that the HF 2HP unit has too small an impeller and moves too little air to get the really fine dust generated by most tools.)

[cgallery]

I've got some anecdotal information that may hurt more than it helps.

I had a friend that works in HVAC stop-by w/ his Dwyer gear. We measured that little HF 1-HP dust collector (not scientifically--we didn't have a long enough piece of PVC to feed it). Anyway, we came up with something like 350 (roughly) CFM.

Now, mind you, this little DC has an airfoil impeller and spins at 6000+ RPM's. Good static pressure #'s (matching that of much larger DC's).

So after my friend leaves I decide I'm going to measure it w/ my Kestrel 1000 (weather vane type anemometer). I get something like 54-MPH at the inlet. Then I throw a 10' piece of 4" hard plastic hose (the stuff w/o the wire reinforcing in it) on and took a measurement at the end of that, and my recollection was that it only dropped by 1.5-MPH.

What I didn't do was try measuring it with a long piece of PVC instead, as I don't have any long pieces of PVC (they all got cut-up when I was sperimenting).

Like I said, it really isn't that useful. I did think to myself that it would be handy to take a measurement w/ 10' of PVC vs. 10' of plastic hose. That may provide some info about how good/bad the plastic hose is.

I will say that there are some circumstances where the hard plastic hose would seem to be a benefit. For example, it doesn't bend that well. Very graceful bends with no transitions that are 5" may be better than tighter 4" bends?

My test may also be invalid (even more so than they already are) b/c a larger DC may have been able to pull more CFM through that 4" pipe. And the flex hose may have trouble w/ that higher CFM.

I will finally add that newer flex hoses have a smoother inner surface than some older stuff I was given by another woodworker. Perhaps the industry has made improvements in how the stuff is manufactured.

[Carlos]

Hmm, seems like I should be able to rig up some sort of test gear. I have lots of 4" hose and fittings. There must be something in the shop I can use or fabricate to measure flow. Any sort of pendulum with minimal resistance should work.

[cgallery]

Hmm, seems like I should be able to rig up some sort of test gear. I have lots of 4" hose and fittings. There must be something in the shop I can use or fabricate to measure flow. Any sort of pendulum with minimal resistance should work.

What will you guys give me to keep my mouth shut about the Cheerios test?

Seriously, you can get a cheap weather-vane type anememeter and get decent relative readings. Just make sure it can handle the duct speeds.

[Carlos]

Aha, Wal-mart weather station should do it! Good thinking.

[SARGE..g-47]

I normally don't get involved with a thread about dust collection as I have seen the debates rage on for years. And the bottom line for me is there seems to be no pin-point conclussions and I highly doubt there will be.

And not just on WW forums as this one, but even a great deal of dispute amongst the upper level echelon considered the sages in the arena of dust collection. The guru tells you one thing and another guru disputes. Then the manufacturer partially disputes both guru's. Then a test is done by so and so at such and such and they come to a slightly different conclussion based on.... whatever!

And this is not contained to dust collection. I have seen raging debates every time a topic of electricity comes up also. Toe to toe with several Electrical engineers in total dis-agreement... with certified electricians that install to code every day chiming in and sometimes disputing portions of the theories of the guys with the degrees.

Not to de-mean anything that has been said here in good faith by all parties in an attempt to help.. but I coming to the conclussion that there is a lot that is truly unknown and will continue to be unknown when the smoke clears about DC's and cyclone systems.. and I don't think that it will clear anytime soon in this area as I glance at 3 WW forums daily.

I just looked at the specs given by HF on the 2 HP DC in question. It does not give impellor size... but it does state that it produces 1600 cfm. It doesn't state the circumstances of how that figure was arrived at. Someone in the chase for a DC may look at that and think it wonderful.

They look at the specs for my 2 1/2 HP Tempest S cyclone with a 14" impellor and 7" in-let and see it is stated at only 1450 cfm. Should the conclussion be that I should save the $850 and get the 1600 cfm for $169 with smaller motor.. impellor and inlet. That certainly sounds like the sensible approach to me.... or does it?

If nothing else.. I get quite a few chuckles out of all of this and probably should stiick to my policy of not getting involved in a discussion of dust collection or electricity. I will write both off as one of the "mysteries of life" and call it a day...

My cyclone fills the chip barrel with chips even with flex pipe.. and it fills the fine dust bin with fine dust. I turn it on.. I turn it off. It works for hours on end as I am in the shop now 4-8 hours a day. I suppose I should be happy even though a better deal could have been had for less if I read the specs before the pruchase. Stupid me....

Good luck with whatever call you make, Carlos...

[Carlos]

No matter what I do, the system will work. I've been running it for years on 4" flex for the main tool run and 4" sewer (horribly corrugated) as a main run for the 2.5" feeds. I have been happy with performance, so in a sense I don't know what I *might* be missing.

However with a complete rearrangement of the shop and new plumbing needed, I would like to do the best thing possible.

Your post reminds me that I may be overthinking this (I always tend to over-engineer), and the 5" flex is certain to be better than what I've used all along. Another important point is that we generally work with the garage doors open, and for half the year we run a swamp cooler (Google it if you don't know, it's only used in dry climates, and moves a HUGE amount of air into the space). I want to add a powerful air cleaner to use the rest of the time, which will help a lot.