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GR on What do you mean by Full Vacuum in Tank / Pressure vesselsBy: GR 
Date: Friday, May 29, 2009
Time: 2:29:59 AM
Vacuum means the internal pressure goes below atmospheric. Full Vacuum is a negative pressure equivalent to 14.7psi or 15 psirounded-off meaning full volume of the container without pressure. In some cases vessel are designed for Half Vacuum which is 7.5 psi.