OK, I got a question! I built a vacuum rig to do better and faster vacuums. It consists of new Yellow Jacket 3/8 vacuum hoses and a three way distributor. Vacuum pump is only a few months old and oil had been changed. I pulled a vacuum on a Masterbilt three door dairy cooler and it took about an hour to get to 300 microns. I know that was NOT right!
I brought the rig home, changed the oil and hooked it up to a 30# recovery tank. I pulled a vacuum to about 60 microns (JB DV-22N) for a couple of hours and then blanked off the vacuum pump (Yellow Jacket SuperEvac 6cfm). I plan on putting a hand valve or ball valve in-line in between the pump and distributor. It raised up to about 265 microns and seems to be holding. Is this good? What is this about new vacuum hoses "off gassing"?
Did another test. Let the pump run for a few hours until the gauge read about 60 microns again. I again blanked off the pump and the microns rose to about 130 and held there for about 30 minutes.
I'm doing all this to make sure my rig is working properly and giving me quicker pull downs.