LDS Features and Operation

Passive Leak Detection
Operation Training
October 2014
Regulatory Requirements
“A cargo tank motor vehicle in other than metered
delivery service must have a means to automatically
shut off the flow of product without the need for
human intervention within 20 seconds of an
unintentional release caused by a complete
separation of a liquid delivery hose (passive shut
down capability)”
US code of federal regulations – 49 CFR chapter 173.315 (n) (2)
Transport Canada Regulations – CSA B620
System Overview
• Concept of Passive Leak Detection
• MC330-331 tank trailers
• Automatically closes valve in the event of a hose
• Microprocessor based technology
• System arms when trailer’s “operating air” is
• Continually monitoring pressures
• Hose failure causes air valve to exhaust, closing
internal valve
Mounting Locations
• Typically protected behind trailer landing gear
• TEST and RESET buttons should face operator
during offloading
Probe Location
• Installed by a US DOT / Transport Canada
authorized facility
• Mounted in the discharge piping of the trailer
Suggested Operational Process
1. Set park brake
2. Drop the piping guard
3. Connect the liquid and vapor product hoses to the
bulk storage facility
4. Slowly open the internal valve – charging the pump
and trailer piping only
5. Slowly open the in-line valve at the trailer hose
connection charging the delivery hose
Process cont.
6. Slowly open the valve to the storage tank
7. Slowly open the vapor return line from the storage
tank – charging the vapor hose (if used)
8. Slowly open the vapor return tank internal valve
into the trailer
9. Engage the tractor power take off
Process cont.
10. While the system is powered, press and hold the test
button – air valve will exhaust, internal valve will close,
alarm will sound a “beep, beep, pause, beep, beep,
pause” sequence
11. This test verifies the system is receiving a good probe
signal. This sound would be present during a delivery if
the probe signal was lost
12. After releasing the test button, press the reset button
again for a complete system reset
*once the trailer system has been tripped, it will be necessary to disengage
the PTO and close the trailer / hose valve in order to reopen the internal valve
System Maintenance
Annual checks recommended
Dry air lines
Probe connector and Dielectric grease
Check +12V and GND connections to ensure
they are secure and free of corrosion
Daily Check
• Energize system
• Press and hold test button
– Alarm will BEEP BEEP PAUSE until button is
– Air valve will exhaust air going to the internal
• Press RESET to clear test and re-energize
internal valve air supply.

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