Valves vary by the amount of rotation required to cover the full range of regulation. Most valves will have a range of regulation. Most valves will have a range from 0° to 90° or 0° to 120°. The maximum travel that can be realized from a 90° actuator and mechanical linkage arrangement is about 120°. The amount of travel to be used is dependent upon the required turn-down ratio (flow rates) between high-fire and low-fire and the flow characteristics of the particular valve.
For initial start-up: (use factory set points)
Adjustment requirements cannot be finally established until after the burner is fired. The valve should work from a mid-open to a closed position when located in the return line when going from low-fire to high-fire.
To adjust amount of travel, loosen base of ball-joint connector located in slotted actuator arm and reposition to desired setting, then re-tighten connector.
A = Decrease travel of metering valve
B = Increase travel of metering valve
C = Increase travel of metering valve
D = Decrease travel of metering valve
E = Quickens travel first 1” of movement
F = Slows travel first 1” of movement
The John Zink 3/8″ rotary metering valves 935000-0511, 935000-0513, and 935000-0520 are no longer available.
If you have one of these valves please call us to go over replacement options.