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June
7, 2000
Manifolded
Piping Systems and Leak Detection Solutions VMI Technical Bulletin
060200 entitled “Mechanical Leak Detectors and Problems Associated with
Manifolded Piping” dated June 2, 2000, addresses specific problems encountered
when using mechanical line leak detectors with manifolded piping systems.
Specifically, the issues of shutting pumps off and preventing additional
pumps from turning on when 3 GPH leaks are detected were reviewed. When using manifolded
piping systems, line leak detection must be addressed.
The preferred method of doing this is double wall piping, containment
sump, sump sensor with shutdown capability, and a catastrophic mechanical line
leak detector to provide redundancy and protection during periods when water may
infiltrate the sump or the sump sensors may not be operational. For existing stations
that do not have double wall piping, this may be a costly solution. In those instances,
the only feasible method is the use of electronic line leak detection.
There are several electronic line leak detection systems being offered
today. Almost all of those are
limited to use with fractional horsepower turbines (1/3 hp, ¾ hp, 1 ½ hp) as
flow rates through those leak detectors are restricted.
When used with 3 and 5 horsepower pumps, flow rates are radically
restricted. This means that
conventional electronic line leak systems are rarely compatible for use in truck
stops and bulk fueling systems where high volume is needed. The VMI
PLC-5000 series of electronic
line monitor solutions is uniquely designed to deliver full flow from high
capacity pumps and has the capacity to automatically stage the start of multiple
turbines, provide 3 GPH line leak detection, .2 and .1 GPH testing. This series incorporates the use of a Central Control Node (CCN) that
will control up to four turbines. The
PLC-5012 CCN is a programming and reporting node that has the capability to
automatically stage the start of multiple turbines upon demand.
At authorization of
the first dispenser, turbine # 1 starts. When
pressure in the line falls below 24 psi, the next turbine is brought on line. Up to 4 turbines may be brought on line in this manner. The lead turbine may
be changed by manually resetting the Master-Slave Select (Option B) switches.
This option allows you to change the master turbine to allow quiet time
to perform a tank test on a specific tank.
It is also possible to incorporate a low level shutoff for each turbine. By constantly
monitoring line pressure, catastrophic line leak detection is provided.
In the event a 3 GPH leak is detected, the primary pump is shut down and
secondary pump(s) are not allowed to start. This system requires
the use of one LDN (Leak Detector Node) mounted to each turbine.
Communication from each LDN at the turbine to the CCN inside the building
is accomplished over existing power lines. This results in a simple and fast installation as no
additional conduit / wiring is required. Sump
sensors may also be monitored with appropriate reporting or shutdown response. The LD-3300 line-check
/ pressure relief directs line pressure to the Leak Detector Node and also
functions as a primary line check valve. The PLC-5012 Staged
Turbine System monitors continuously for a 3 gallon per hour leak.
Testing for monthly monitoring of .2 gallons per hour, and annual line
testing, .1 gallons per hour can be
activated. An additional benefit is
that thermal contraction problems are completely eliminated. If you have existing
LD-3000 line leak detectors in place, they can be easily modified in the field
for use with the PLC-5000 system. For information on
this or other unique line solutions contact your local distributor or VMI,
800-367-0185.
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Last modified: November 15, 2008 Vaporless Manufacturing, Inc. 8700 E. Long Mesa Drive Prescott Valley, Arizona 86314 E-mail: vmi@vaporless.com 1-800-367-0185 Fax (928) 775-5309 |
