vacuum vent pipe melting !!!!!!!!!!!!!!!

[ianppk]

hello all,
my name is ian i have the older large leeson 14hp vacuum system,
shopbot advised me to run a 4 foot steel pipe from the exhaust and the remainder could be standard pvc,well as it would be that does not work,i have 20 feet of pvc that is in danger of melting and falling down after a 500 dollar install and mount,the pipe is melting after only 1 hour usage,im not wasting my breath even calling shopbot anymore,any suggestions other than the obvious --- do not use pvc at all?
its melted 20 feet away from the exhaust! the remainder looks like a wet noodle-lol
thank you all very much!

[wberminio]

Ivan

I have 16 hp regeng pump and used CPVC as exhaust.5 years no issues!

The metal pipe is conducting heat to the pvc

[kevin]

My is not as big same thing no melting .Can it be a problem with you exhast something blocking ?

[gene]

PVC is rated to 120 degrees Farenheit CPVC is rated to 200

[miked]

had the same problem with shcedule 40 pvc. however after switching to schedule 80 pvc problem was solved only problem is coming up with enough money to by the expensive pipe!

[gene]

How did you connect the metal pipe to the pvc ? If you use a rubber adapter between the two maybe this would stop the heat transfer between the two

[paul_z]

Ian,

I think you are running into stagnation. You have so little flow through the pump that almost all of the 14hp is going into heating what little air is going through. You might want to try allowing a larger airflow. Maybe an inlet bypass of some sort.

Paul Z