This device is a mandatory part of a grease trap installation that allows air to enter the pipe, necessary for proper flow, and restricts the volume of water going into the trap so that it isn’t overwhelmed, allowing grease to exit the trap. 99% of the time, if a sink bowl won’t drain, there is a blockage of the flow restrictor, which must be installed prior to the grease trap.
The flow restrictor is a SERVICEABLE device, and should be installed so that it can be! Most blockages can be cleared by sending a brush through from the grease trap side, but sometimes it is necessary to remove the blockage from the sink side, if the blockage is larger than the restrictor hole. Over time the restrictor will buildup with grease and block both the air vent and the small flow restrictor hole.
