|
|
|
|
Click Here For Print Friendly Version
AST Bleed-back Testing Problem: Above Ground Storage Tanks, Marinas
Scenario: Fuel storage for a marina typically sits high above the water level
and flows downhill to a docking area. In some rural areas, above ground storage
tanks are fairly common for normal fuel dispensing. There are other scenarios
where the leak detector may sit higher than the dispensing system. Our recommended piping system for a system such as this is as
follows:
A. On
discharge of submersible pump install a normally closed solenoid.
B. Install
a VMI Leak Detector Adaptor (Part # PLC-5040)
C. Install
VMI 99LD-2000 Leak Detector When trouble-shooting possible leak detector problems, it is very
helpful to know what the resiliency (bleed-back) of the line is. It is also necessary
to know the bleed-back when installing an ARM-4073 Automatic
Repressurization Module or an ISM-4080/4081 Integrated Shutdown Module. An
important programming feature of these two products depends upon setting the
proper timing sequence to assure the leak detector has time to reset if a leak
is present. When testing a typical service station, it would be performed at the
farthest or highest dispenser in the piping system. When measuring the
bleed-back, we turn the pump on, let it go to full pump pressure, turn the pump
off, and measure how much fuel goes into the beaker as line pressure drops to
zero. A typical bleed-back may be 100 ml. If you did this on a system where the leak detector is higher than
the dispensers you will probably drain the entire pipe and you would not get an
accurate bleed-back reading. The proper method of measuring the resiliency in the above scenario
is as follows: 1. Turn the pump
off. 2. Install the
LDT-890 Leak Detector Tester into the line test port of the PLC # 5040 Leak Detector Adaptor 3. Turn the pump
on. 4. Watch the
right hand gauge of the LDT-890 as it attains full pump pressure. 5. Turn the pump
off. 6. Put the large
beaker under the drain hose of the LDT-890. 7. Open the
4-way valve to Dispensing Nozzle position. Whatever amount of fuel drains into the beaker when the pressure
gauge drops to 0 psi is the bleed-back. Test the leak detector as per normal LDT-890 instructions to assure
it functions properly. |
|
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 |
