Tank Considerations: Pressure vs Vacuum.
How can I determine whether a commercially-available 10 gal portable AIR PRESSURE tank (Max 135 PSI) can safely be used as a VACUUM ACCUMULATOR tank for deep vacuum (eg: 1000 microns/0.13 kPa/29.88 HG)?
I have a 1.5 CFM two-stage HVAC vacuum pump I intend to use for degassing RTV mold making/casting materials. The material vendor recommends using a 8 CFM pump for this application. The issue is one of having sufficient capacity to draw enough vacuum quickly enough to degass the materials within their working time, ie: before the materials set up such that they no longer flow adequately. My budget does not permit changing up to a higher capacity pump at this time.
The thought occurs that by using a tank to accumulate vacuum, choosing the smallest suitable vacuum chamber and taking steps to further reduce any voids with packing, then my 1.5 CFM pump could be serviceable for the task.
Even if considerations preclude drawing such a tank down to a deep vacuum (eg: 1000 microns/0.13 kPa/29.88 HG), providing a vacuum relief valve set to a safe working value and creating a partial vacuum would be helpful by speeding up initial evacuation of the chamber. With the chamber stabilized at the tank's partial vacuum, a valve to the tank can be closed, leaving the pump to take the chamber down to the desired deep vacuum.