Leak test requirements and length - 2, The lsu (leak sensing unit) - 2, Communications - 2 – Franklin Fueling Systems TS-LLD Installation Manual User Manual
Page 12
Overview and Theory of Operation
(Continued... )
The
0.1 gph annual test is started manually from the control unit (also known as a
manual test). On the other hand, the gross 3.0 gph hourly test and the
intermediate precision
0.2 gph monthly-compliance test both start and run
automatically.
Quiet-times
, where no dispensing occurs, are required to start
and finish any line leak test.
Leak Test Requirements and Length
The 3.0 gph hourly test starts after every dispense and takes about 3 minutes
of
quiet-time
to finish.
The 0.2 gph monthly-compliance test automatically starts after a 3.0 gph test
passes
unless
a previous 0.2 gph test has already passed within the last 24
hours. The monthly compliance test either runs, passes, and resets the day-count
to 00, or, advances a day if no test has passed after 24 hours. Depending on
conditions of the line and product, the
0.2 gph monthly-compliance test needs
13 minutes to 4 hours of
quiet-time
to finish.
The manual 0.1 gph annual test needs 4 hours of
quiet-time
before it’s
started, and takes about 13 minutes of
quiet-time
to finish after it starts.
The LSU (Leak Sensing Unit)
The LSU (Leak Sensing Unit) has an O-Ring sealed valve at its base, which forces
all of the fuel flowing from the submersible pump through the LSU. A
microprocessor based printed circuit board is contained in the LSU. It uses a
proprietary technique to measure the actual product flow rate through a sensor
tube within the LSU, which can indicate a leak.
In most cases, the only required field wiring connections are two wires that are
connected in parallel to the existing Submersible Turbine Pump (STP) power-feed-
lines. A special copper sheathed, Mineral Insulated Cable (
MI Cable) connects the
LSU to the electrical junction box at the pump discharge head.
Communications
The LSU not only receives power from the existing pump power-lines, but it
transmits data (communicates) over these lines. One of the power lines is routed
through a communications
pickup coil
inside the Control Unit (CU).