Troubleshooting and Analysis
System Conditions That Can Be Ignored
Page 6-14
MDE-5394B VaporTEK™/VaporTEK-3 Controller Board 110 V UL® Vapor Recovery Collection System for Encore® 500 S
Start-Up and Service Manual · March 2019
Dispenser-side Leaks
Air leaks on the dispenser side of the flow meter are less likely to occur, and will be detected
by the system only if they are large. Because these leaks will be “downstream” of the flow
meter, they will not be sensed directly. However, they can, if large enough, cause the dispenser
to shut down, and they can be detected by careful examination of the flow data in the log.
During a running transaction, the vapor pump is set up to a certain speed that will draw the
same flow of vapor as of the fuel being dispensed. When there is no leak in the system, all of
the vapor will flow along a single path- through the nozzle and hose, then through the vapor
tubing, and pump.
Because the system was calibrated with this same setup, the amount of flow that the pump will
draw at any given speed will always be about the same. However, if an air leak develops on the
opposite side where no transaction is running, then the system will draw air from the leaking
point, which reduces the vapor performance on the active fueling point. A test with max
simulation value of 99 LPM will show a maximal vapor performance, but if this performance
is lower than expected, then the leakage point needs to be detected before a vapor pump
replacement is required.
As discussed above, long-term pump wear will likely cause the A/L Ratio to drop below the
low end of the allowable range, just as an air leak on the dispenser side of the flow meter will.
However, pump wear and the resulting decrease in flow will affect both sides of the dispenser,
whereas an air leak will presumably be on only one side. Therefore, the way to tell the
difference between these two situations is to examine the data from both sides of the dispenser.
If the A/L Ratio has dropped below the low end of the allowable range on both sides of the
dispenser, the likely cause is long-term pump wear, and the solution is to recalibrate the
system. If it occurs on only one side, the cause is likely an air leak between the flow meter and
the pump on the side where the A/L Ratio has dropped out of range.
