Part No. 920525 Rev A - Wayne 3/VISTA series Service Manual

5.2.3. Flow Control Valve "On" Full Regulated Flow
Flow control valve "On" full regulated flow occurs during the main portion of all
sales. At this time, the coil is energized with bursts of current of longer duration,
pulling the pilot further off it's seat, relieving the pressure balance, and allowing
the diaphragm to open by an amount relative to the distance between pilot and the
pilot orifice. The position of the pilot is constantly moving in very small incre-
ments based on the signals sent from the computer relative to controlling a
specific blend ratio and/or maintaining a maximum flow rate of 10 GPM through
a hose. As the computer senses the need to increase or decrease the amount of a
particular feedstock, it will send signals to the coil of longer (to open) or shorter
(to close) duration. As a result, the pilot moves up or down causing the diaphragm
to follow its movement and achieve the proper amount of flow.
When the delivery is complete, the coil is de-energized, allowing the pilot to
return to its closed position. This allows pressure to build on the back side of the
diaphragm, forcing it to close and seal the outlet port thereby stopping flow.
5.3. iMETER
The iMeter is designed and assembled around a modular type concept using fewer parts and
allowing easier access for service. The iMeter module Figure 5-3. contains two meters in one
assembly and the Intelligent Pulser. Each of the two meters in the iMeter module is a positive
displacement meter. The pistons in the meter are in-line with respect to one another - one
piston is 180° out of phase with the other. In remote dispensers, the bottom of the iMeter
body is attached to the filter/strainer casting as shown in Figure 5-1. In suction pumps, the
bottom of the iMeter body is attached to the top cover of the compact pumping unit. There
are no external moving parts on the iMeter. Calibration is accomplished electronically. A
procedure for iMeter calibration and Intelligent Pulser operation is found in Section 3.
5.3.1. Check and Pressure Relief Valve
There are two Check
removable covers, as shown in Figure 5-3. The top mounted location allows for check valve
replacement without draining the meter body. 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
sure buildup. The relief valve is set to relieve pressure between 30-50 psi.
June 2001
Pressure Relief (C
&
PR) valves located atop the iMeter module under
&
PR valve would relieve the pres-
&

Part No. 920525 Rev A

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