Vacuum pressure is really atmospheric pressure pushing on the opposite side of the diaphram that you apply the vacuum to. That's why it is limited to a pressure of 15 PSI or 1 Bar. If the area of the diaphram is 1 square inch the maximum force that could be exerted by the diaphram is 15 pounds. If the diaphram is 2 square inches, the force exerted would be 30 pounds, ETC.

Unlike air or hydraulic systems no pressure release is needed in vacuum systems because atmospheric pressure is the limiting factor.

P E H