The PIVSU-EX is designed to supervise the position of a Post Indicator or Butterfly valve in hazardous locations. The device mounts in a 1/2" NPT threaded nipple to the valve body. When properly mounted, the indicator of the Post Indicator valve or the operating mechanism of the Butterfly Valve will be pushing against the return spring of the PIVSU-EX so that as the valve is operated, the spring in the PIVSU-EX pulls the trip rod over and activates the switch. To aid with installation the trip rod length is adjustable. This device features a UL listed explosion proof switch enclosure.