Two Stage Solenoid Valve (Non-Blenders Only) - Wayne Dresser Vista 1 Series Service Manual

5.2.

TWO STAGE SOLENOID VALVE (NON-BLENDERS ONLY)

This section describes the operation of the Wayne two stage solenoid operated diaphragm
valve that does not have the built-in check and pressure relief function. This valve is used
in conjunction with a separate check and pressure relief valve (C&PR Valve).
The C&PR valve is located at the meter inlet. Once a delivery is complete and the
diaphragm valve is closed, the product pressure between the check valve and the nozzle
will be held at the pressure of the last delivery. If the pressure should build up due to
temperature rise in the hose or a car runs over the hose, the relief function of the C&PR
valve would relieve the pressure buildup. The relief valve is set to relieve pressure between
30-50 psi. The same C &PR valve is used in blenders and non-blenders.
The two stage AC operated solenoid diaphragm valve has two basic functions. It controls
all flow through the dispenser and acts as a positive shutoff valve.
The two stage valve itself consists of three main parts:
• The diaphragm valve
• The actuator
• The actuator coils
The diaphragm valve is the main flow valve. It controls the full flow through the dispenser.
The actuator is an electrically operated solenoid valve. It controls the diaphragm valve by
switching the diaphragm into and out of full flow and allowing a slower bypass flow around
the diaphragm.
The actuator coils control the actuator itself. When the coils are energized "poppets" inside
the actuator are moved to expose flow paths through the actuator.
Together these three parts will be referred to as the "flow control valve" throughout this
section.
The flow control valve performs three separate functions. It provides for slow product flow,
to be used in the slowdown at the end of preset sales and it allows for full product flow and
is the means for positive flow shutoff
In all Wayne non-blending dispensers using the two stage solenoid operated diaphragm
valve the general order of operation is the same. At the outset of a sale the slow flow coil
only is energized causing slow product flow to start. After a small amount of product is
delivered both coils are energized. This initiates full flow. For preset sales the dispenser
will switch back to slow flow at a pre-determined point.
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Part No. 920160 Rev A February 1997