Bridle, also named stand pipe, is a vertical pipe connected to the process tank or vessel so that the level of process liquid within bridle is always equal to the level of process liquid within tank or vessel. Level bridle is intended for installation of multiple level transmitter such as level gauge or level transmitter. These level instrumentation are installed to the bridle instead of the vessel or tank.
The use of bridle for level transmitter reduces the number of nozzles on the vessel or tank. If each level instruments has two nozzles, then they require six nozzles on the vessel. However by using bridle, the number of nozzle that should be provided on the vessel or tank is only two (or three) for the bridle.
Bridle is commonly constructed from 4” pipe and provided with vent and drain connection for maintenance. Below picture shows bridle and its level instrumentation attached to.
Level bridle with multiple level instruments must have isolating valves installed between bridle and instrument for maintenance purpose.