Pressure Vacuum
In an inert gas system, what are the effects when pressure vacuum breaker malfunctions and actions taken?
shipboard operation.
A PV is installed on an oil tankers tank to prevent a pressure or vacuum build up. Either can stress the tank walls and cause buckling and or failure.
An inerting system displaces the oxygen in the air space above the liquid in the tank thereby minimizing or eliminating the potential of igniting the fuel rich air above the liquid
if a PV valve were to fail open after the tank was inerted, air containing oxygen could return into the tank thereby negating the effectiveness of the inerting. If the PV valve is stuck closed it is possible to over pressureize the tank during inerting. Also the displaced air may not be vented properly trapping a pocket of oxygen (air) again either negatating or minimizing the inerting.
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