DC Setup - PVC Sch 20 vs. Sch 40

[ssmith1627]

I'm ready to get some ducting in place for the HF 2HP DC I bought about a month ago. I ended up rearranging my shop somewhat to keep those runs as short as possible and I think I may have an arrangment now that will work -- at least until I bring another tool into the picture !

Can you guys explain to me the difference in sch 20 and sch 40 PVC ? Are both available at HD and Lowes ?

I plan on using the flex hose only where I have to -- like the drop down from the ceiling to the shark guard on the BT.

Just trying to get all the different pieces laid out so I can connect PVC to the DC and to any flex hose I want to use on the other end of the runs.

Thanks,
Steve

[LarryG]

Just the wall thickness, basically. Schedule 20 is fine for a woodshop DC system, but check on the availability of all the fittings you will need.

Also, be aware that neither the inside nor the outside diameter of virtually any PVC pipe nominal size will *exactly* match that nominal size, which might make finding adapters a bit of a headache.

[ssmith1627]

I can already see this is going to be a lot of fun to piece together ! haha

How are you guys attaching PVC to PVC ? I'm sure my first few attempts at setting this up will have to be rethought once I get into actually using them. I can't imagine gluing up the joints at this early stage. Drill some pilot holes and screw the pieces together ? Or is there a better way ?

Thanks again,
Steve

[Tom Miller]

Did you see a Sched. 35? Like Larry pointed out, the availability of fittings should be taken into account. In my small sampling, I've seen Sched. 40 and Sched. 35 fittings, but nothing for thinner wall. I use Sched. 35.

Regarding gluing the joints -- I don't, nor do I recommend it. As far as air-tightness is concerned, I don't think you need anything but a press fit. For mechanical strength, I use anywhere from one to three short pan-head screws (3/8" - 1/2").

Regards,
Tom

[dkhoward]

I think what he is refering to as schedule 20 is really sewer and drain pipe. Check at HD and Lowes, both carry a full line of fitting for the S&D piping. My whole DC system is plumbed with S&D. Some of the DC fitting can get a little dicey as to the fit, but a little duct tape and some ingenuity go a long way. I like S&D because of the lighter weight and the fact that the inside of most of it has some kind of coating that tends to make stuff slide down it better. As to the fittings themselves, all of mine are slip fitted together and then I run two short self tapping sheet metal screws thru the thicker wall of the fitting into the pipe. It took some doing but you can do it without perforating the inside pipe. The fittings seem to be friction tight enough that I don't lose a noticeable amount of air flow through them and they are easily dissasembled if I do get a hang up or if I want to modify the system. I have found that the plstic blast gates from Rocker fit very well into the fittings.

[Tom Miller]

I think what he is refering to as schedule 20 is really sewer and drain pipe.

I guess that's what I'm trying to clarify. I've seen (and currently use) Sched. 35, which is referred to as S&D, and is also known as ASTM3034. I've also seen ASTM 2729, and I don't know the schedule # on that, but I think it may be 20. I don't think that stuff is generally referred to as S&D, but I could be wrong. The pipe itself should be fine for DC, but since it's fairly thin-walled, I don't know how well it fits S&D fittings.

Regards,
Tom

[Popeye]

I used the thinwall S&D. 4" hose quick disconnects fit tight into the fittings. the only thing I was able to get at the local hardware store were 90deg elbows, y's, caps and end to end connectors. Here is the link to all mine, http://bt3gallery.fhauto.com/view_al...umName=album15 Pat

[Brian G]

I followed Tom's lead when I plumbed my shop (see the thread a few below yours). I used the ASTM 3034 (Sched 35), and the styrene fittings (found by the drain tile in HD) rather than the pricier PVC fittings.

I admit to being frustrated when people would talk about using S&D, and it seemed like different people were using the same terminology to describe different types of pipe (i.e., ASTM 2729 versus ASTM 3034). Both of those are referenced as S&D, but the wall thickness is different.

Things I like about the ASTM 3034:

1. It's cheaper than Sched 40.

2. The styrene fittings, as mentioned, are cheaper than PVC

3. As Tom suggested in other threads, the clear, wire-reinforced dust hose will stretch over the 3034 if you clip and remove a few wraps of the wire.

4. Common dust collection fittings (like you'd get at Rockler or Woodcraft) will fit snugly inside the 3034 pipe. No fasteners or shimming/taping are needed.

5. The aluminum blast gates that you can get at Rockler or Woodcraft fit inside the 3034 with a few raps of a mallet.

It just all came together easily. I don't doubt at all that the ASTM 2729 can work well. I used sheetmetal screws to hold the joints together, because it tended to want to spin in the fittings at each wye.

[gjat]

Sch40 pvc is heavy wall. DB120 is thin wall. Gray pvc is for electrical, white is for water. They both can use the same fittings. The overall OD of pipe is the same between 40 and db120.
just knock the fittings together without glue and they'll stick. In fact, I'd wipe them with oil to make sure you can get it apart. In fact, you probably don't have to glue too much at all.

[ssmith1627]

These are the fittings I had seen at Woodcraft here:
http://www.woodcraft.com/family.aspx?FamilyID=5815

They say they fit schedule 20 PVC. I didn't realize the differences between sch 20 and sch 40 until reading all this from you guys.

Was just at HD. They have the thicker walled sch 40 stuff. And above it they have the thinner walled 2729 stuff. I didn't see a schedule # on the 2729 but it's definitely the thinner walled of the two.

I saw the gray as well -- but those didn't seem to go above 2 1/2 or 3 inches in diameter, at least from what this one HD had.

I'll try a piece of the 2729 type and see what I end up with. Need to just walk in HD with the Woodcraft fittings and my blast gates and see what fits what ! Think they'd mind??

Thanks guys. As always, knocking it around like this is what it takes to get past the learning curve on any new topic. Much appreciated.

Steve

[Tom Miller]

...Need to just walk in HD with the Woodcraft fittings and my blast gates and see what fits what ! Think they'd mind??

If it gets you any attention at all, I know what I'm gonna bring with me to HD from now on.

Even though that particular PVC-to-hose connection that you reference is made to fit Sched. 20, that doesn't mean Sched. 20 fits Woodcraft's DC fittings in general. I do know from personal experience that Sched. 35 (ASTM 3034) will go snugly over Woodcraft/Rockler blast gates, and fits perfectly inside the cheaper, much less bulky styrene (not quite as glossy white as PVC) S&D fittings.

Sorry if it appears I'm banging on this a little hard. But, if you can wade through all the options, and get the right parts, it all fits together like a glove.

Regards,
Tom

[ssmith1627]

Seems to be two sections of fittings at Lowes. One for the schedule 40 PVC -- the boxes have red or purple labels. The red says DWV and the purple does not -- not sure what the difference is really in the two.

The other section is for the thinner walled stuff, be that schedule 20 or whatever. They had the fittings further down the aisle and on the other side from the PVC stuff. They call it "outside drainage" to make it even more confusing. The only thing I can think is the thicker walled stuff is really meant to handle sewage and the thin walled stuff to handle rain water.

They do seem to have 90 degree elbow's, 45's, 22.5's, Y's, etc. They all fit the 2729 thinner 4" pipe so no issues there. They did not seem to offer longer turn Y's or elbows so there is a limit to what you can find.

I got some work started on my setup over the weekend. One fork from the D.C. being split into two -- blade guard and back of the saw for the BT. The other fork also being split into two -- router table and floor sweep. That will cover my needs until I add another tool into the picture.

Steve

[R.C. Woodworking]

I just ran 2" gray pipe to my craftsman 6.0 shop vac. for my DC, Haven't used it yet, wondering how it is going to work?? I have 4 points of entry gated each one, should there be a static concern?

[John Hunter]

I just ran 4" S&D for my HF 2hp unit. I used a self drilling screw on the fittings and taped the outside joints with duct tape. Made some of the adapters myself such as the 4" to 1 1/2" for my Miter Saw. I picked up 1 1/2" hose at the local hardware and a fitting for it, cut a piece of plywood using a circle jig on my bandsaw that fit into the 4" S&D drilled the center and placed the 1 1/2' connector into it and hooked the hose to it. Had no trouble finding 4" S&D fittings at Lowe's. Used Y's, and 45's. They had the 90's but I used 2 45's with a straight piece of pipe between them thus eliminating the sharp turns of the factory 90's. To make the blast gates fit inside the S&D nice and tight I put a couple of wraps of duct tape around them before driving the gate in. Worked great. I also found that if you cut a couple of wraps of wire from the 4" hose and heat it with a hair dryer that it fits over the S&D very nice and you can use a 4" hose clamp to keep it in place.

[LCHIEN]

I just ran 2" gray pipe to my craftsman 6.0 shop vac. for my DC, Haven't used it yet, wondering how it is going to work?? I have 4 points of entry gated each one, should there be a static concern?

Welcome to the forum.

It's been sort of a urban legend that static will cause a dust explosion with woodworking dust collectors. Static can be a irritating thing, you can just ground your tools, which they should be anyway.

With 2" piping, this is probably OK with a shopvac (smaller shop vac if 6.0 is the HP). most of this duscussion is with purpose built dust collectors with 10-12 inch impellors whose air flow is usually rated in the 600-1500 CFM, a shop vac may only e 50-100 CFM.

You don't say what you have it hooked to, it's been my experience that they (shop vacs) will fill up to fast and maybe can't keep up with devices that make lots of big fluffy chips (planers and jointers) but will probably work OK with
sanders, bandsaws, routers and drill presses.