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.
A Bridle is a special piping arrangement done by the piping designer to hold the Level Instruments for a Vessel or Tank.
Level instruments such as: Level Glass (or Gage), Level Transmitter, Level Controller and Level Alarm.
You should note that there are three parts here. In the middle there is a “Stand Pipe” or “Stilling Well”. This is just a pipe to connect all the instruments to instead of connecting them directly to the vessel (not shown is the connection from the “Stand Pipe” to the Vessel). On the left is a Level Controller (LC). On the right is a Level Glass (LG).
The LG is there to, a) give the operator a quick local visual indication of the liquid in the Tank or Vessel and, b) to give the operator the ability to have a visual indication of the liquid when setting the LC controls. The valves are for shut-off of the individual item for removal and repair without shutting down the whole plant.
