Cameron Demco - Worm Gear Operated; Automatic Valves; Maintenance Procedures; Troubleshooting

10
TC-003001-01 / Rev 2
CLOSED OPEN CLOSED
Figure 12 – Valve with Gear Operator
WORM GEAR OPERATED
Worm gear operators are recommended for valves larger than 6 inches. Clockwise rotation of the handwheel
closes the butterfly valve. Counterclockwise rotation opens the valve.
Gear operators are always mounted with the input shaft perpendicular to the pipe axis for handwheel clearance.
Each operator has an arrow on the top of the gear, which indicates the "OPEN - CLOSED" position of the valve
(Figure 13).
AUTOMATIC VALVES
Butterfly valves with their quarter turn operation are easily adapted to automatic actuators for remote operation.
To prevent water hammer, actuators should close the valve slower than 6 to 8 seconds, open-to-close. Rapid
closure causes water hammer which can break or otherwise damage valve parts.
MAINTANENCE PROCEDURES
TROUBLESHOOTING
Table 6 - Troubleshooting
T rouble
Probable Cause
Remedy
The valve will not seal
properly.
The seat and/or disc is worn or
damaged.
Replace worn parts.*
Foreign matter is present between seat
and disc.
Operate several times to wipe clean.
Operator stops are not set properly.
Adjust stops to proper setting.
The valve is hard to
operate.
Build-up of solids or roughness on edge
of disc.
Operate several times to wipe clean or disassemble valve
and clean disc edge.*
Operator is not installed properly.
Reinstall operator in proper alignment with valve stem.