Troubleshooting and Analysis
System Conditions That Can Be Ignored
Page 6-12
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
System Conditions That Can Be Ignored
The following system conditions can be ignored:
•
Environmental and Fuel Conditions
- As the temperature changes, the concentration of
the vapor changes as well. The pump speed is set to match the liquid flow during the
calibration procedure, but the pump flow will vary with vapor concentration and other
related factors. As the temperature varies with environmental conditions, as the fuel
formulation changes seasonally, and as other conditions cause the vapor concentration to
change, the flow of the vapor will deviate from the calibration curve. There are two
reasons some of these deviations can be ignored:
- The variations due to these causes alone are too small to drive the A/L Ratio out of range.
- The system has an automatic regulation feature that compensates for short-term
variations and drives the A/L Ratio closer to 100%.
•
Improper Use of the Nozzle
- This will happen routinely, but should not cause the A/L
Ratio to deviate by more than a few percent, and should not occur for ten consecutive
transactions. This is one reason the regulations are written to allow for the A/L Ratio to
deviate by more than +/- 5% at 38 LPM or +/- 10% on half performance point.
•
Minor Variations in Pump Performance
- The relationship between pump speed and
vapor flow will change as the pump wears over time. As discussed above, the pump speed
is based on the relationship that exists between pump speed and vapor flow when the last
calibration was performed. As the pump performance changes (due to seal wear, system
pressure drop, and so on), the amount of vapor flow will differ from the fuel flow, and the
A/L Ratio will vary accordingly. However, this is a long-term effect. It will take many
months before the A/L Ratio goes out of range from this cause.
There also will be short-term variations in pump performance that cause some scatter in the
A/ L Ratio results. This is usually too small to drive the A/L Ratio out of range. Therefore,
short-term variation due to this cause should be expected and can be ignored. The longer-term
performance changes due to system wear will eventually cause the system to require
recalibration. For more information on recalibration, refer to
.
