What psi rating do you need to use in black poly for vacuum?

[Bruce L]

I might possibly be 75-100' short on my 1&1/4" black poly dry line,what psi rating should I grab from Home Depot or something so it doesn't collapse under high vacuum levels,probably 27" or so?
Thanks,Bruce

[spencer11]

Normal black mainline is 100 psi, thats what most people seem to use

[maple flats]

Some maple distributors even sell 80 PSI, Maybe Webb does too. That will work. I've never heard of poly pipe collapsing from vacuum.