Sequence Of The Dispensing Cycle (Blenders Only) - Wayne Dresser Vista 1 Series Service Manual

2.1.2. Push-to-Start Models,
• The slow valve coil is energized two to six seconds, depending on option program-
ming settings, after the submersible pump relay is energized.
• After a small amount of fuel has been dispensed, the fast valve coil is switched on
and both coils are now energized together.
• In preset sales the fast coil is de-energized just prior to the final shut-off amount. The
slow valve coil is then de-energized when the final amount is reached.
• When the nozzle is returned to the nozzle boot, the nozzle switch goes back to the
constant +5 VDC and the sale is complete.
2.2.

SEQUENCE OF THE DISPENSING CYCLE (BLENDERS ONLY)

• When the nozzle is removed from the nozzle boot or the Lift to Start lever is raised,
the constant +5 VDC that the computer supplies to the nozzle switch goes to ground.
At this point the lighted buttons (grade select or cash/credit, depending on the model)
will flash indicating that one of the buttons must be pressed.
• When one of the lighted buttons is pressed, the constant +5 VDC that is supplied to
the switch goes to ground. This signals the computer to begin its reset cycle.
• When the dispenser receives an Authorization signal either from the control system
or from the Authorize switch in the dispenser, the correct submersible pump relay
will be energized.
• The computer performs a self test and flashes eights, blanks, then resets to zeros, on
the main sale display.
• After the dispenser resets, the proportional flow control valve(s) is energized with
just enough current to barely open the valve(s) and allow a slow flow.
After a small amount of fuel has been dispensed, the valve(s) is energized with
enough current to be in the fully open position and allow fast flow. During the sale,
the valve(s) will be continuously controlled with the proper amount of current to
provide the correct blend ratio and limit fuel flow rate to a maximum of 10 GPM.
• In preset sales, the current received by the proportional flow control valve(s) is
reduced to the barely open position just prior to the final shut-off amount. The
valve(s) is then de-energized when the final amount is reached.
• When the nozzle is replaced in the nozzle boot, the nozzle switch goes back to the
constant +5 VDC, and the sale is complete.
* The submersible may have been energized in the previous step depending on the data setting in
programming Option 36. Refer to the Option Programming Manual part number 920205 for more
information.
** The maximum allowable flow rate in the United States is 10 gallons per minute.
4
Part No. 920160 Rev A
continued
*
**
February 1997