2006-10-18 06:20:21 · 9 answers · asked by Dave 1 in Science & Mathematics ➔ Engineering
First, do the calc.
I must interject here. The reason is that so many here assume that the pipe in question will behave the same in pressure as vacuum.
I don't know the material properties of PVC. One omission is the working environment temperature of the pipe.
Assuming everything is equal, I would wager that this pipe can do better in compression than tension. This is the difference between typical rated psi, which produces tensile stresses in the pipe, and vacuum stresses, which puts the material in compressive forces.
Get the material properties.
One would have to simply do the calc to find the comp. stress for PVC and determine the material properties to come to a recommendation.
2006-10-18 20:42:38 · answer #1 · answered by daedgewood 4 · 0⤊ 0⤋
Do not use the pressure ratings (e.g., 100 psi) to evaluate the suitability of PVC for vacuum. The failure modes under pressure and vacuum are entirely different. The differing failure modes mean that things don't scale the same way. Larger pipes are more susceptible to vacuum failure than smaller pipe.
Youe 27" vacuum is about 14 psi external pressure. For small diameter pipe (2-inch and less) you will be fine. Stay away from irrigation PVC which has a wall thickness of 1/16" and less. Plain old schedule 40 will work fine. If you go to large pipe (6-inch and greater) you may have trouble. As one answerer said. the run length of the pipe is important as well, much more so than for pressure pipes. However, after a certain length (I woul dguess 10-20 diameters long) increasing the length no longer decreases the vacuum capability.
2006-10-18 08:53:50 · answer #2 · answered by Pretzels 5 · 1⤊ 0⤋
Pvc Vacuum Pipe
2016-12-15 15:11:34 · answer #3 · answered by ? 4 · 0⤊ 0⤋
High Vacuum usually refers to vacuum pressures below 0.1 Torr, (760 Torr is atmospheric pressure at sea level). which is about 29" Hg.
You shouldn't see much pressure degradation with schedule 80 PVC at the pressure you are suggesting. If the wall thickness is less than 3/16" you may see collapsing of PVC over lengths of a few feet, But short runs of a few inches should be fine. Basically the thicker the better, 1/16 PVC walls will collapse at about 15" Hg. or less.
2006-10-18 06:39:47 · answer #4 · answered by Harry C 2 · 1⤊ 0⤋
Should be fine for vacuum service I have several systems running at around 25" hg vacuum.
Don't use if for compressed air. Its not recommended and I've had bad results trying that. When it breaks it shatters and throws shards of broken PVC every where bad show.
2006-10-18 06:50:41 · answer #5 · answered by Roadkill 6 · 0⤊ 0⤋
Yes, Most PVC pipe is rated at 150 psi. So the 27" Hg is acceptable.
2006-10-18 06:28:13 · answer #6 · answered by Anonymous · 0⤊ 1⤋
A 27" column of mercury (Hg) will exert a pressure of about 14 lbs. p.s.i Schedule 40 PVC which is normally found at the local hardware store will withstand pressures well over 100 lbs. p.s.i.
If greater pressures are required then you can purchase Schedule 80 PVC which is thicker walled and designed to withstand even higher pressures.
2006-10-18 06:43:57 · answer #7 · answered by waldon l 2 · 0⤊ 2⤋
Yeah I would say yeah you probably can. It might be a good idea to get a second oppinion though.
2006-10-18 06:24:13 · answer #8 · answered by pollywollydoda 3 · 0⤊ 0⤋
yeah i would also think you can.
2006-10-18 06:25:57 · answer #9 · answered by Gart888 2 · 0⤊ 0⤋