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Valve Installation
Butterfly Valves
Dominion™ Butterfly Valves have nylon-coated cast aluminum bodies and nylon-coated ductile
iron discs with stainless steel stems.
The valves have bushings around the handle shaft to keep the water from leaking out of the
shaft. As the valve ages, these bushings tend to dry out. The dryness, combined with dust and
dirt, inhibits valve operation which increases the force required to turn the valve handle. This is
not a serious problem when the valves are operated individually
– until the problem gets
progressively worse and excessive force is required to turn the valve handle. If the valve
resistance becomes too high, the actuator can develop enough torque to shear the valve stem.
Routine preventive maintenance for these valves, without removing them, is to lubricate the
stem and bushing with a food grade, silicone base, penetrating lubricant. The pneumatic
operator must be removed to expose the shaft and bushing.
The valves are highly corrosion resistant and should provide satisfactory service for many
years; however, it is possible for them to become coated with foreign material due to an
imbalance of the water chemistry or the build-up of hair, lint, or other material that can wrap
itself around the valve stems.
If you are inspecting a valve, it is necessary to remove most of the securing bolts at that valve.
The resilient lining provides the seal between the valve and the flanges so that no gaskets are
required. The flanges must be opened or spread slightly so the valve can slide out of position.
Ensure that the valve disc is in the closed position before attempting removal.
The valve shaft is square with a scribe mark. If the scribe marks run in the same direction as the
piping (parallel) the disc is in the open position. If the scribe marks are perpendicular to the
piping, the disc is closed. The disc does not have to be 100% closed for shut-off purposes.
The resilient lining of the valve provides a seal between the process water and the stainless
steel shaft. If the position of the lining is altered due to coating or buildup of scale, etc., this seal
could be broken. If the valve resists turning after cleaning, lubricate the shaft ends from the
inside and outside. If your service schedule includes removal of the valves for inspection, the
resilient lining should be coated with the same lubricant.
If the valve disc does not move freely with normal pressure after treating it with the lubricant,
consider replacing the valve. Replacement valves are not expensive and usually cost less than
the labor and replacement parts required to repair an existing valve.
Summary of Contents for DEFENDER SP-27-48-487
Page 14: ...Page 14 General Installation Schematic ...
Page 15: ...Page 15 DIMENSIONAL REFERENCE Standard Defender ...
Page 16: ...Page 16 Assero Defender Reduced Height Defender ...
Page 17: ...Page 17 Reduced Height Defender ...
Page 77: ...Page 77 APPENDIX ...
Page 78: ...Page 78 Electrical Schematic ...
Page 79: ...Page 79 Head Loss Curve ...