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37
February 1997
Part No. 920160 Rev A
5.3.
PROPORTIONAL FLOW CONTROL VALVE (BLENDERS ONLY), continued
The proportional flow control valve controls flow and blend ratios in the dispenser. This
valve is used in conjunction with a separate check and pressure relief valve (C&PR valve).
The CP&R 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 will 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 pilot operated proportional solenoid valve performs three basic functions in the
dispenser. It provides positive shutoff, regulates the ratio of blended feedstocks, and
controls the flow rate through the hydraulic path by limiting the maximum flow rate
through a given hose.
The pilot operated proportional flow control valve consists of two main parts:
•
The proportional valve
•
The valve coil
The proportional valve is an electrically operated solenoid made up of a body and an oper-
ator. It controls all flow through the dispenser.
The valve coil controls the operator of the valve. The coil is energized with a pulse width
modulated (PWM) signal that sends discrete “bursts” of current at a set frequency level.
When the coil receives this signal, the pilot inside the operator reacts to the changing
magnetic field and moves up and down depending on the amount of current through the
coil. The position of the pilot relative to the pilot orifice in the diaphragm controls the
amount of flow.
In all Wayne blending dispensers using this valve, the general order of operation is the
same. At the beginning of a sale, the coil is energized with a minimum current level,
allowing slow product flow to start. After a small amount of product is delivered, the coil
is energized with more current to initiate full regulated flow. For preset sales, the dispenser
will switch back to slow flow at a pre-determined point.
5.3.1.
Flow Control Valve “Off” No Flow
Flow control valve “Off” or no flow occurs when the inlet to the valve is
charged. But there is no flow required from the particular valve as in the
instance where a submersible pump motor is running because another fueling
point is being used. The pilot stays closed allowing pump pressure to build on
the back side of the diaphragm, closing the outlet port.
Содержание Dresser Vista 1 Series
Страница 1: ...1 Vista Series Blending and Non Blending Remote Dispensers SERVICE ...
Страница 4: ...Part No 920160 Rev A February 1997 ...
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Страница 12: ...2 Part No 920160 Rev A February 1997 ...
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Страница 62: ...52 Part No 920160 Rev A February 1997 ...
Страница 76: ...66 Part No 920160 Rev A February 1997 FIGURE 7 8 NOZZLE BOOT ASSEMBLY LIFT TO START ...
Страница 77: ...67 February 1997 Part No 920160 Rev A FIGURE 7 9 NOZZLE BOOT ASSEMBLY PUSH TO START ...
Страница 83: ...73 February 1997 Part No 920160 Rev A APPENDIX A TROUBLESHOOTING FLOWCHARTS ...
Страница 110: ...100 Part No 920160 Rev A February 1997 ...
Страница 111: ...101 February 1997 Part No 920160 Rev A APPENDIX B SERVICE INFORMATION AND CONNECTOR PIN OUTS ...
Страница 128: ...118 Part No 920160 Rev A February 1997 FIGURE B 20 ISB ASSEMBLY CONNECTION PINOUTS FOR MGD Refer to Table B 1 ...
Страница 134: ...124 Part No 920160 Rev A February 1997 ...
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