Piston transmitter

A piston transmitter is a glandless pressure transmitting device. For the protection of the mechanical seal, it provides a barrier fluid pressure that depends on the pressure of the pump or the fluid handled.

The piston transmitter consists of a double-wall reservoir in which a piston effects the separation of the barrier product from the product handled. See Fig. 1 Piston transmitter

In order to generate the required barrier pressure, the bottom part of the cylinder is connected to the pump's discharge nozzle, or to a product line under the required pressure. The top part of the cylinder is filled with barrier fluid and is connected to the area between the two seal faces of the double mechanical seal. The pressure in the seal chamber is increased by the smaller piston area on the barrier fluid side. See Figs. 11, 12 Shaft seal