View Full Version : PVC schedule
lemains
08-13-2008, 12:54 PM
Hi,
Sorry if this question is stupid.. but I am kind of new to this, but learning.
As I understand all PVC has a maximum service temperature of 140° F
Two questions:
1. Does this apply to all PVC regardless the wall thickness? It wouldn't make sense, right?
A 0.413 wall should resist more temperature than a 0.173 wall.... right?
2. Are the the SDR series PVC and the Schedule 40 PVC made of the same material? Or one of them is more resistant to temperature than the other?
link: http://www.harvel.com/pipepvc-sch40-80-dim.asp
Thanks a lot,
Master Plumber 101
08-13-2008, 01:22 PM
I thoght you could go to 160 degrees before needing to switch to cast or another type of metal. Sorry I can't give you concrete answer.:confused:
Gary Slusser
08-13-2008, 04:44 PM
Sch 40 PVC is rated for pressure at 73*f. No PVC is rated for hot water use.
The only plastics that are rated for hot water applications are CPVC and PEX. And then I think the max temp is 100*f; that what is used for the pressure rating anyway.
jimbo
08-13-2008, 08:25 PM
There is some absolute temp number which is "not to ever go there" for PVC. I don't know that number. But any schedule of PVC pipe has a temperature vs. pressure spec. For schedule 40, max temp allowed for 150 PSI is 73º, which is why it falls outside the range of household use.
Gary Slusser
08-13-2008, 09:40 PM
Jimbo, IIRC, the sch 40 I used had a 425# rating at 73*f.
The thicker material will take longer to heat up, but once it does it will have the same problems as the thinner pipe. SDR is just a very, very thin pipe and because it is a drain material, the inside diameter MUST conform to the i.d. of sch. 40 pipes which might interconnect with it. Because of the thinner wall that means the o.d. is smaller than sch. 40 pipe and requires an adapter bushing to match the other pipe's o.d.
toolaholic
08-14-2008, 08:05 AM
Interisting pvc is used for W.H. POWER VENT exhaust
jimbo
08-14-2008, 08:18 AM
Yes, I was a little confused on the numbers. This derating schedule shows full operating pressure at 73º, and derated to 0.2 of full pressure at 140º. It mentions that above 140, the plastic may not retain its shape!
http://www.engineeringtoolbox.com/thermoplastic-pipes-temperature-strength-d_794.html
Gary Slusser
08-14-2008, 09:58 AM
Anyway we got there, I couldn't remember the 425 until your numbers jogged my memory. It can't be used for warm or hot water.
IT is mixing with cooler air so the temperature remains in the safe range.