Rosemount Inc.

James E Walish

Myles L Miller

Thomas P Peterson

Lee A Mattison

Decorative cap for a process transmitter

A transmitter that provides an output indicating pressure difference between a line pressure and atmosphere outside the transmitter is made intrinsically safe by coupling the sensor cavity as well as other cavities where ignition can occur to atmosphere only through flame quenching paths. The opening in the transmitter housing in which the sensor is mounted has a plug including a sensor cavity that holds the sensor, and a fitting which is couplable to the pressure line. An isolator is used for transmitting the process pressure to the sensor through an isolator diaphragm acting on an incompressible filling the sensor cavity and transmitting pressure through a hole that is shaped to provide a flame quenching path. The passageway flame isolates the sensor from the process fluid line. The opposite side of the sensor is connected to atmosphere only through paths which are flame quenching because of the passageway shape. The plug is an assembly that can be made easily inserted and removed, and provides intrinsic safety even if there is failure of some of the components such as the isolating diaphragm or welds holding portions of the plug together.

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Buffalo, MN, United States of America

James E Walish