Benchset Range - ATO-FC

Shutoff capability is directly proportional to the ability to "unload" the actuator down to a 0 psig pressure level. If there is any instrument that will NOT unload down to the 0 psig output pneumatic pressure, the shutoff capability will be reduced. Devices that can cause a problem by NOT unloading down to 0 psig are:

- I/P Transducer with a 3-15 psig output range; the device will only unload down to 2 - 2.5 psig. For the above actuator, the shutoff capability is "halved"; i.e. (2.5/5) x 600 psid = 300 psid.

- Some pneumatic controllers.

A device that DOES unload down to 0 psig is a POSITIONER.