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TEST PROTOCOL - LDT 890 Leak Detector Tester
Installing LDT-890 Turn power off, lock out, and tag out the submersible pump breaker. Proceed to the dispenser at highest point of elevation in the system. If there is no difference in elevation, go to the farthest dispenser. Secure the area with safety cones or other appropriate safety apparatus. Using
an approved safety test can, hold the nozzle handle open and relieve any built
up pressure and fuel into the test can. Trip safety impact valve. Remove the plug from the test port of the impact valve. Install the 18-inch whip hose into the test port and connect it to the quick disconnect connection of the hose connected to the test cabinet. Reset safety impact valve.
Check for Leaks Set the 4-way valve on the test cabinet to Pressure Step Test. Turn the power on at the submersible pump breaker. Turn the dispenser pump lever on. Watch for pump to achieve full operating pressure as seen on the right hand gauge. Check all connections for leaks.
Purging Test System Set 4-way valve to Dispensing Nozzle position. Purge test system completely of air by allowing approximately 1,000 ml of product to flow into the large beaker. Turn the 4-way valve to Pressure Step Test. Using the dispenser nozzle, run approximately two gallons into the test can to purge air from piping system. Note pump pressure on right hand gauge. Record pump pressure (No. 1 on Test at Dispenser Form). Trip the safety impact valve.
Leak Test: Phase 1; Calibrating a leak at 10 PSI Turn
4-way valve to 1. Calibrate G.P.H.
While watching the left hand gauge, use the 2. Calibrate
Pressure knob to adjust pressure to 10 psi. (Turn knob counter-clockwise to increase pressure and
clockwise to reduce pressure.) Using
the 140 ml beaker, time leak rate for 30 seconds. (A 3-gallon per hour leak is equivalent to 95 ml per 30
seconds.) To adjust the leak
rate, use the 3. Calibrate Orifice knob.
(Turn knob counter-clockwise for larger leak rate and clockwise for
smaller leak rate.) After
adjusting the 3. Calibrate Orifice knob, the pressure on the left
hand gauge will change. Reset the
pressure back to 10 psi and time the leak rate for another 30 seconds.
Repeat this process until the desired leak rate is achieved. Set
4-way valve to Pressure Step Test. Turn
pump control handle off. Record
Gallons per hour rate (No. 2 on Test at Dispenser Form). Cont.
on Page 2
Note static pressure from right hand gauge. Record Static Pressure on Test Form (No. 3 on Test at Dispenser Form).
Bleed-back Test Turn
4-way valve to Dispenser Nozzle. Drain
pressure to 0 psi using large beaker. (Note: Piston Leak Detector may take 60 to 90 seconds to
completely drain. All VMI leak
detectors are Piston Leak Detectors.) Record
amount of product in Bleedback Test with pump off (No. 4 on Test at Dispenser
Form). Step-through
Time Turn
4-way valve to Pressure Step Test. Turn
pump control handle on. Using
stopwatch, time the right hand gauge as it moves from 0 psi to full pump
pressure. Record Step-through
time to full flow (No. 5 on Test at Dispenser Form). Turn dispenser off.
Leak Test: Phase 2, Does the leak detector search for and find a leak. It is important to note that all mechanical leak detectors have three (3) different and distinct leak positions or steps the leak detector goes through during the test process. Those steps or positions are:
The pressure that the leak detector steps through or stays in during “2, Leak Search Pressure” will vary by manufacturer, model and submersible pressure. The VMI series of leak detectors manufactured prior to February 1999 have a search pressure of approximately 12 to 15 psi. The 99/LD-2000 and 99/LD-2200 series search for a leak at 20 to 24 psi. Competitive leak detectors may have a search pressure of approximately 12 to 15 psi. It
is important to calibrate the VMI LDT-890 at 10 psi as noted in paragraph Leak
Test (Phase 1). Turn
4-way valve to Dispenser Nozzle. Drain
line pressure to 0 psi. Turn 4-way
valve to G.P.H. Test. Turn
pump on. Needle on right hand gauge should rise to search
pressure and remain indefinitely. This
indicates the leak detector is functioning correctly.
Record Leak detector stays in leak search position “Yes __X__”
(No. 6 on Test at Dispenser Form). If
gauge goes to pump pressure, leak detector has failed.
Record Leak detector stays in leak search position “No
X “
(No. 6 on Test at Dispenser Form).
Record Pass or Fail (Leak Detector Test on Form)
Disconnect LDT-890 Turn power off, lock out, and tag out the submersible pump breaker. Turn 4-way valve to Dispenser Nozzle. Drain to 0 psi. Remove test apparatus and re-install test plug on impact valve. Reset the safety impact valve.
Diagnostics Failure
to find a 3gph leak could mean:
Bad
leak detector
(loose tolerances in metering system). REPLACE. Too
much line resiliency
(Refer to Bleed-back Test). Maximum
bleed-back for a VMI LD-2200 leak detector should be no more than 250 ml.
Maximum bleed-back for a VMI 99 LD-2000 should be no more than 400 ml.
VMI has available special leak detectors that will handle excessive
bleed-back. Thermal expansion occurs when cold fuel enters warm line. Test for thermal expansion by bleeding line pressure to 0 psi from bottom of dispenser. Wait 5 minutes. Record pressure. Wait 5 minutes. Record pressure again. If line pressure continues to build, thermal expansion may be overcoming the leak detector. You must wait for temperature to stabilize.
Slow Leak Detector Normally
a leak detector should take 2 to 4 seconds to go through leak search to full
flow from the time the pump is turned on. If it takes longer than 4 seconds,
here are some factors that may be occurring: Excessive
line resiliency. The greater the
resiliency, the longer it takes to fill the line and look for a leak. Leak
detector may be bad or out of tolerance. Small
leaks in the delivery system, while they include line leaks, they may also
include; packer ‘o’ ring leak back into the tank, leaking past the
functional element or pump check valve. Note:
VMI LD-2000 and LD-3000 leak detectors have their own integrated check
valve. Contaminants may affect this
check valve allowing pressure to leak by and back from the line to the tank.
Leaking solenoid valve in a dispenser may pressurize the nozzle hose.
Leak detectors may have a seal leak out through the vent line into the
tank. Thermal
contraction
occurs when warm product is pumped into a cold line. This most often occurs in the fall and winter months and can
result in extreme line pressure loss, even to the point of causing the leak
detector to reset. If a leak
detector is extremely slow to step through, thermal contraction may be
the cause. It may be identified by
installing a pressure gauge at the impact valve of the farthest dispenser.
Start the submersible, allow the leak detector to step through, turn the
submersible off. Wait 5 minutes, note pressure and repeat the procedure.
Again record the pressure. Repeat
4 times. Pressure drop should fall to a higher pressure each time.
If pressure drop remains constant to the same pressure, suspect a line
leak. Leak detector does not reset when leak is introduced with pump off Head
pressure may cause some leak detectors to not reset. Some leak detectors do not reset with more than 1 psi (38
inches) against them. That means
they will not find a leak that is above the 38-inch level.
That is why a leak detector should always be tested at the highest
dispenser.
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**CLICK HERE FOR LDT 890 CONVERSION CHART
**CLICK HERE FOR LDT 890 TEST FORM
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Last modified:November 14, 2011 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 |