VIMS
Air leak: the secondary wall is no longer tight, but the vacuum in the interstice is still maintained. There is no immediate risk for environmental pollution, which allows a certain reaction time for trouble shooting.
Water leak: Ground water enters through the secondary. No immediate environmental risk. Allowance for sufficient reaction time for maintenance.
Product leak on a tank: STP will continue running to empty the tank. Tank refilling should be prevented.
Product leak on a pipe: Primary pipe is leaking. The STP will create overpressure in the interstice and product might pollute the environment. In case of product in the interstice, the STP will be shut down immediately.