My Vacuum/Pressure Set-up
Well I finally got my vacuum set-up done for my pressure pot. I am using a venturi vacuum pump (top left of photos) off the compressor, but arranged my gauges and valves so I can do vacuum and pressure (I need this mainly for banksia). I used a heap of in-line ball valves with simple tee's because the three way ball valves cost a lot more (almost 3 times more).
Photo 1 - Vacuum drawn using air. My venturi pump works under 5.5bar (80psi) air pressure and should draw 29". After 1 min I have 22" Hg (75kPa) vacuum, 4 min 25" Hg(85kPa) and still rising but sloooowly (it is a big old cast aluminium pot).
Photo 2 - Vacuum with air turned off (and pot held vacuum without loss).
Photo 3 - Vacuum released and pressure applied to pot at 3bar (40psi). The pot can take 5.5bar (80psi) max, but I worry about my resin saver moulds leaking at that pressure.
Photo 4 - Pressure holding with air disconnected (and again pot held pressure).
My pot is pretty old, at least 40 years. It started as a glue pot in a workshop, then a paint pot for my father, now a casting pot / paint pot for me. It is a cast aluminium pot and approximately 25mm (1") thick minimum. Hopefully fatigue failure is still a long way off.
Cheers