I have been looking around online at vacuum pumps. I found many made by Thomas that are vacuum diaphram/oiless. They say they pull to 27hg ( in Phoenix, low altitude, i bet it would pull 29hg), and are 3.4cfm.
The Gast pumps i am finding used are higher priced than used Thomas pumps.
Anyone using a small Thomas or Gast pump? Any buying tips or suggestions?
I used larger size Thomas pumps in the past, (oil lubricated rotary vane pumps) but about 50% of the pumps I bought burnt their motors after 6 months or so.
Thomas reps said there was nothing wrong, but that series of pumps have been replaced anyhow.
I use 2 dual rocking piston Gasts, 29.5" hg…maybe only 1.5-3cfm, but they are great, and can run open if needed. Never had a problem, and if you HAVE to take apart and clean, very very simple system.
And, only likr 500$
Riff, does your Gast rocking piston pump evacuate air from the bag quickly?
We got our rebuilt Thomas vacuum pump a few days ago… only got as far as plugging it in to test if the motor worked ok - passed.
It didn’t come with rubber or spring feet so we have to make or buy some. All we did was wire up an electric cord to test it. It has it’s own capacitor it comes with all wired up. Two fans to keep the pistons and motor cool. It’s quieter than a robinair 6cfm i was using. I’d guess it makes around 40 db of noise. We need to build a clean box to house the pump… dust free because the connecting rods and pistons are all open to contamination by design. I’ll just rig up some paint booth filters with wire mesh on the box. That should also quiet it down. Now I know why CBD had their vacuum pumps inside a small closet.
Sure. It’s 3CFM I think. I don’t want quick anyway, so I can make sure I have no bridging, since all I do is infusion. you can get any size you want I reckon. It’s a bit vibraty, which means don’t trust the gauge ON the pump, unless you use an oil filled one 
yeah , i noticed the thomas pump we just purchased is a small vibration machine. I haven’t even had the time of day to install some rubber feet on it or get it hooked up.
I do have a liquid hg gauge… i believe it still works so I’ll give that a go… probably mount it on the outside of the box we make for the pump. The only other thing i really need is a timer set up so i can just walk away and go home while it’s vacuuming.
One pump is on little soft rubber feet mounted on a metal channel, the other is bolted on a thick fiberglass panel. Both sit on soft silicone sheets (3/8" thick) just to lessen more vibration. it works well. I infuse mainly on a rolling cart, so the vibration normally runs through the entire table!