Originally posted by Fred in NC
<br />Harbor Freight venturi vacuum pump:
http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=3952
This type of vacuum pump takes a LOT of air to operate. You will need a good sized air compressor. My pancake compressor will not work with it.
Fred,
I have the HF pump and my compressor was purchased from them also.What I did was install 2 1/4" ball valves on the maifold.One on the input side and one on the suction side.(I had to change the fitting on the suction side to pipe thread instead of the HVAC thread that came with the unit.
I also installed a Vacuum gauge in the suction side.
To operate teh "pump" I open up the suction side of the manifold,then I open up the supply valve.Depending on how much vacuum you can pull on the first shot,keep an eye on the vac. gauge.When it maxes out shut the vac valve first and then the supply valve.
Let your pancake compressor recover it's pressure.
I can normally get 26" or better on one shot this way but your pancake may take more.
I keep the maifold hooked up to the chamber and repeat the process when I see the gvacuum gague needle fall.
I keep repeating this until I don't get any more bubbles out of the material I am stabilizing.