Severe service valve positioner

摘要

A severe service valve positioner (100) for switching the position of a valve is designed to operate safely in potentially explosive environments. The severe service valve positioner (100) includes a housing (110); a service cartridge (105), including an electronics compartment and an electro-pneumatic compartment (115), wherein the service cartridge (105) is completely modular and detachable from the housing (110); an electronics compartment, including a potentiometer (315) having a lockable setting and a reduction gear (505,510) for locking the potentiometer (315) into place and for increasing the accuracy of a measurement of the angular displacement of the potentiometer (315) with respect to an initial position; an electro-pneumatic compartment (115), including a current-to-pressure converter known as an I/P motor, which is environmentally segregated from the electronics compartment (105); a pressure sensor assembly (320) which is environmentally segregated from the service cartridge; and a field termination (120) assembly. The environmental segregation of the electronics compartment, the electro-pneumatic component (115), the pressure sensor assembly (320), and the field termination assembly (120) serves a safety function in potentially hazardous (e.g., spark-generating) environments. The modularity and detachability of the service cartridge (105) enables it to be removed from the valve positioner quickly and easily for service or routine maintenance.