Mechanical Line Leak Detectors


This component is mounted onto the leak detector port of submersible turbine pumps (STPs).   It is designed to automatically detect a leak in a pressurized piping system.


Product can be removed from a UST using either pressure or suction.   Pressurized systems rely on a pump (STP) located inside the tank that will push product from the tank through attached piping to an emergency backup generator, another tank, processing equipment, or a dispensing device.


When the STP is activated the piping is pressurized with product from the tank.   The mechanical line leak detector (MLLD) is designed to detect a leak in the piping during pressurization.   If a leak is detected the MLLD will trip into "slow flow" mode.   This generally restricts the flow of product through the piping to less than 3.0 Gals per minute (GPM).


MLLDs must be UL® rated, third-party certified by an independent testing organization, approved by the National Work Group on Leak Detection Evaluations (NWGLDE), compatible with the product stored in the tank, and have a COMM 10 Material Approval for use with USTs installed in the State of Wisconsin.  


Consult with the manufacturer of the MLLD(s) installed at your UST facility to determine maintenance, operation and repair requirements.