One solution to avoid clogging or crystallization in differential pressure transmitter sensing lines is to purge the lines with an inert fluid. However, introducing purge flow creates errors by causing unequal pressure drops in the lines. To solve this, the purge flowrates need to be equal. An example of a reliable solution is to use a flow indicator like the Sho-Rate Series 1350G, coupled with a flow controller FCA8900 to set and maintain equal purge flows even as main process pressures vary.