Working with pvc
 

Can someone point me to a website that explains the basics of working with pvc for someone who has never done this before.

How to cut it?

How to prime/glue it?

How to attach it to bulkheads, valves etc and how to split the flow from one pipe into two?

How to plan the routing of the pipe to minimize loss of pressure/flow?

Thanks.

(1) PVC cutters

(2) PVC glue

(3) Depends on what type of bulkheads you have, if it's double-threaded, use adaptors (don't forget to use teflon tape), if it's single threaded, then you'll have to glue it.

(4) Use "T"s

(5) (A)I would measure to make sure every part is in correct sizes and lengths, then put them together WITHOUT the glues to see how they fit together, then glue them up...(use alittle amount of vaseline when you are pre-assembling them, so they will be easier to come out when you want to glue them)

(B)For your returns, minimize as many elblows as possible, you'll get faster flows with straighter routes

Thanks for the advice.

I read a really good article about working with pvc a month or two ago and now I can't find it.

I am wondering about T's to split flow. For example a 1" pump output dividing into two 3/4" lines for the return from the sump. A regular T should cause loss of pressure/flow just from the shape of the T. Do they make "Y" shaped T's?

Also I'm wondering about the pro's and cons of flex pvc versus regular pvc, and how to glue the flex pvc. Also where any good Canadian mail-order places to buy all the plumbing parts, for those of us who live far from a Home Depot.

above was a good description but a couple things.. if you are only going to be doing a limited amount of work with PVC don't worry about the cutters, they can be expensive and are only good up to 1" (unless there is a larger size I haven't seen yet) any wood cutting saw works awsome on PVC. so had saw, compound miter saw ect..

I personaly would not use vasaline in the dry assembly as this is a greese that you have to remove prior to gluing. Just dry fit your parts they are never that hard to take apart. In adition to the glue you want to use primer (look for clear glue and primer if you can fined it. the primer cleans the surface and allows the glue to work a lot better.

to prime and glue all you do is open the primer attached to the cap will be a cotton swab on a wire, run this around the end of the pipe and then the inside of the fitting it will be going into. this is fine to dry at this point but keep it clean. with the glue you do the same over the primed areaas and then pres them togeather hard and slowly twist them inside each other till it sets up.

a tip I will throw in is to not build it in to big of chunks with out putting a threaded union in. this raises the cost by about 5 bucks for each one but it allws you to install/remove in smaller chunks and makes life much easier.

as for bulkheads get a threaded bulkhead and then you buy a threaded to slip adaptor. the one end threads into the bulkhead and the other glues to the pipe.

I will take a bunch of pics of various stuff tonight and post it for you.

Steve

To cut the pvc pipe for my new tank, I just used a small hand saw (a hacksaw works too) cutting it freehand. If you do choose to use a power mitre saw, be very careful. It is critical to hold the pipe solidly so that it does not rotate as the blade cuts through it. If the pipe is allowed to spin, the blade could grab and throw the pipe out of the saw violently.

I just have a couple things to add.

Vaseline - bad idea. grease & glue don't mix.

Use a pvc primer - the purple stuff is just as good, you just have to be a little neater if you care about looks. Same applies to grey glue. Glue should be applied over the primer WHILE IT IS STILL WET - don't let the primer dry ! Remember to hold the fittings together for 1/2 a minute or so or they can push apart on you.

Use silicone on threaded connections - teflon tape by itself tends to weep over time.

Flex pvc uses the same fittings & primer, different glue

Don't get all anal about flow through tees and fittings - it is usually insignificant. Too small of piping is the real flow killer. Bumping up one size from the pump discharge size is usually a good idea.

Most of these supplies are available fron pool/spa dealers.


Jim

Thanks for all the replies.

For silicone on the threaded fittings, do you mean the same silicone as is used to glue glass ie. aquarium silicone?

Yep, just smear it on the male thread like pipe dope, screw it together, and let set up before pressurizing.

Jim

as an alternitive to silicone which i dont like to use on threaded fittings, I like to use liquid teflon, it comes in a can similar to the pvc glue and spreads on with the applicator provided, works great! non toxic too, flex pvc will give you the least amount of head loss as the curves are smooth, I prime and glue right away, all saws work but I do like my PVC saw, I also have pipe cutters for 1 1/2" pvc(steve), and they do go up to 2" but are only reasonably used for low pressure pipe, you would need to close them with a vice to cut scheldue 40pvc, if using hard pvc pipe using long sweeping elbows helps dramatically to improve flow, and steve's mention of using unions is as good as gold, you will hang yourself later if you ever have to take apart your plumbing and you didnt use unions...as said, test fitting is a life saver

edited for accuracy

So completely wrong I don't know where to start, sigh. It will do no such thing, other than to REDUCE friction loss and perhaps increase flow in a particular application.

"Dramatically" is quite an overstatement IMO - slightly is a better term. If you understand friction loss and friction loss tables, they show that elbows typically aren't a huge "detriment" to a typical system. If long sweep elbows were so wonderous as everyone makes them out to be, they would be a standard plumbing item - which they are not.

Jim

Well thanks for the help and advice, there are a lot of different opinions, I will take what makes sense to me and go with it.

Can someone explain to me the difference between "standard threaded bulkhead" and "double threaded bulkhead"?

flex pvc
 

Hi JimE
Is the flex PVC you are talking about, what they call spa flex, clear with diamond shaped mesh in it?
You say that you can use normal fittings, primer but the glue is different.
Can you tell me specifically what glue? Most if not all the flex fittings I have seen are held on with hose clamps.Avoiding the steel clamps, but getting a reliable joint would be great.

Man, I really had a hard time to take them apart.... you guys must be so much stronger than I am......if not vasaline, use something else then.....but I personally don't think a little bit of vasaline is that hard to remove tho....

Re: flex pvc
 

flex pvd (spa flex is a commen name for it. it is white and it looks ribbed. go to any hot tub place and they sell it. except i was told to use the same glue as you do for regular PVC with it by the people who use it all the time (hot tub builders)

the stuff you were thinking about is reenforced vinal tubing.

Steve

That's a bit of a gray area, depends on the suppliers terminology. Double threaded should just have female threads on both the "inside and outside of the tank". Std would only have a female threaded connection "outside thetank" and just a smooth bore inside.

No, spa flex is solid white with a spiral wire (plastic). The proper cement (in the common weld-on brand) is #795. This is good for flex-ridgid and IME I haven't had any problems with ridgid-ridgid in low pressure applications. On a side note, most spaflex will also take and inside barb fitting and ss clamp.

"the same glue" could be any number of products. There is a weld-on 747 Pool 'R Spa that is rated for both, but it is usually hard to find and is more expensive than 795. What I would call regular PVC cement is 704 or 705 and it is not suitable for flex. The flex glue is more flexible because of course, flex flexes..... As far as advice from hot tub builders, think brain cells vs glue and resin fumes..... :biggrin:

Jim

Jim you sound like you know what your talking about but sweeping elbows make a significant difference in my opinion, not only can they flow up to 30% more water with the same plumbing scematics but they also will usually save you about 20% in eletrical costs by reducing the friction.

Here are some examples:
http://www.canreef.com/photopost/dat...empic.jpg?7048
Two elbow types and three pipe sizes were used to illustrate the importance of correct plumbing.
Study the results below to understand these principles:
Elbows vs. Sweeps
Flow vs. Pipe Size
Vertical Head vs. Total Dynamic Head (TDH)
Pumping Cost vs. TDH
NOTE: Centrifugal Pumps (not self priming) perform best with flooded suction (pumps filled by gravity) as shown. The suction pipe should be nonrestrictive. To control pump’s output, put a valve on the discharge side.
http://www.canreef.com/photopost/dat...t-med.jpg?9357
Friction Loss in PVC Pipe
From the chart at left, using gpm and pipe size, find the friction loss per 100' of pipe.
Example: 40 gpm in a 11/2" pipe = 10' loss per 100' of pipe. 40' then causes about 4' of head loss.
Next find the friction loss caused by the fittings. Please note that the friction loss depends on the fitting diameter. A standard 1.5" elbow is equal to about 4' of pipe; long elbows, sweeps, and 45° elbows are equal to about 2' of pipe; straight through a “T”, about 3' of pipe; and a 90° turn through a “T”, about 9' of pipe.
Example: 40 gpm through 5 standard 1.5" elbows = 20' of pipe, which equals 2' of head loss. Add this to the pipe’s head loss and the actual vertical head height in feet to get Total Dynamic Head (TDH).
http://www.canreef.com/photopost/dat...chart.jpg?8056

Hopefully this helps a few folks out...

edited for accuracy :idea:

Uh, still no. I'll give you a visual. Three cylindrical tanks 23ft tall with identical pumps screwed directly into the bottom. 1st tank is 2"diameter (pipe), 2nd is 12"dia, 3rd is 10'diameter. Say for example, the pumps have a max head of 15' - all tanks would fill to the 15' level right? Ok, now you stick on 3 pumps with a max head of 40' - all tanks will completely fill and overflow at the exact same gpm (ignoring the friction loss in the 2"pipe). How can that be when the weight of 500,000 lbs of water in the 10' tank is pushing down on the pump? They all are pumping against 23' of head. If you stuck a pressure guage on the bottom of each tank there would be 10psi on all three. The situations are identical and the "weight" of the water has absolutely no bearing on the performance. And remember that pressure (or weight as you call it) is omnidirectional - it is distributed in all directions, not all of it directly down into the pump. Now does it make sense?

Jim


[/quote]

yeah that makes sense, sorry bout that, dont know where my brain was there. Too much yard work, lack of oxygen to the brain I reckon....lol I believe I was confusing "backpressure" with headpressure.... opps, of course there would be less restriction using larger diameter pipe, if anything, the excessively oversized pipe would increase the head foot limit of your pump, as the pump curves and stated head limit are based on backpressure which decreases with larger diameter pipe. only problem you could run in to with dramatically oversized pipe is that you would be operating your pump at its peak running capacity, you would want to create a little extra backpressure at the discharge with a ballvalve so as not to burn out your pump prematurely...
But I do think that the sweeping elbows make a big enough difference in my books, and wallet.

"Now to remove my foot from my mouth...."gota get off the crack.... :redface:

I just checked out my local building supply store and all they have is ABS fittings so next time I'm down in Vancouver I'll pick things up, is Home Depot a good place to get everything all at once or should I head to a specialty plumbing supply store? I will need to buy some 1" and 1-1/2" pvc and elbows, T's, etc as well as the PVC primer and glue.

They're ok on smaller stuff, but the selection gets more limitted on the larger sizes. Try somebody like terasen in irrigation supply.

also, here's a how to guide on cementing & working with pvc pipe

http://www.ipscorp.com/wo_html/wo_pd...w_To_Guide.pdf

Jim

Thaks Jim.