In pneumatic valve automation systems,it is common to hear the following terms for valve positions:"fail open(FO),""fail close(FC)"and"fail last(FL)".These terms refer to the position the valve must take in the event of a failure in the system.In cases where the failure is loss of energy used to move the valve actuator,what do we use to move the valve to the desired failure position? The most common systems are via energy contained in pre-com-pressed springs.These are known as single-acting actuators.These systems have limitations in the amount of energy they can deliver and the space they occupy.This article explains how pressurized gas can be stored to be used as a backup system for failure actions and how to do this more efficiently with the use of pneumatic pressure boosters.
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