Spring Adjustment - Fisher D4 Instruction Manual

Instruction Manual
D103042X012
WARNING
When ordered, the valve configuration and construction materials were selected to meet particular pressure, temperature,
pressure drop, and controlled fluid conditions. Responsibility for the safety of process media and compatibility of valve
materials with process media rests solely with the purchaser and end‐user. Since some body/trim material combinations
are limited in their pressure drop and temperature ranges, do not apply any other conditions to the valve without first
contacting your Emerson Process Management sales
WARNING
Avoid personal injury or property damage caused by possible actuator failure. The use of a rigidly‐mounted support on the
actuator casing may cause additional stress on the actuator leading to premature wear and/or failure of the actuator
components.
CAUTION
To avoid product damage, inspect the valve before installation for any damage or any foreign material that may have
collected in the valve body. Also remove any pipe scale, welding slag, or other foreign material from the pipeline.
1. Before installing the control valve assembly, inspect it for any damage and for any foreign material that may have
collected in the valve body.
2. Remove any pipe scale, welding slag, and other foreign material from the pipeline.
3. The control valve can be installed in any position, but normally the actuator is vertical above the valve. Install the
valve so the flow direction arrow on the side of the valve indicates the direction of the process flow.
4. Install the valve following local and national piping codes when they apply to the application. For screwed
connections, treat the external pipe threads with a good grade pipe compound. For flanged valves, use suitable
gaskets between valve and pipeline flanges.
5. If continuous operation is required during maintenance and inspection, install a conventional three‐valve bypass
around the valve.
6. Connect loading pressure for the Spring‐to‐Open configuration to the 1/4‐18 NPT connection in the upper casing
assembly (key 23) as shown in figure 5. The Spring‐to‐Close configuration loading pressure connection is in the
lower casing assembly (key 39) as shown in figure 4.

Spring Adjustment

The spring has a fixed pressure span over which loading pressure will stroke the valve. Adjustment of the spring
compression shifts the span so that more or less loading pressure is required to start travel. Since the span does not
change, there will be a corresponding increase or decrease in the pressure requirements at the end of the valve stroke.
In order to maximize shutoff pressure drop values, the actuator spring must be accurately adjusted for each Input
Signal Pressure Range. If the actuator has been disassembled or pressure conditions have changed, the spring may
require adjustment. Refer to tables 2 and 4 to determine the Initial Spring Set values based on the Input Signal range
that is available to the actuator. These values include packing friction.
office.
D4 Valve
July 2015
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