DeZurik APCO CVS-250A Manual de instrucciones - Página 9
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Maintenance
(Continued)
6. Install the Retaining Rings (B60) and Clevis Pin (B59) to secure the Cushion Arm to the cylinder
rod eye.
7. Install Counter Weight Arm (B19) and Weight (B29) or Spring (B59) to the Pivot Shaft (A13). If
equipped with lever & spring, then hook end of spring thru Eye Bolt (B61).
Operation
These valves may open or close, swinging the counterweight/spring loaded arm without
warning due to flow changes from pumps starting and stopping. Servicing or working
around these valves while the pipeline is under pressure can cause personal injury or
equipment damage.
Workers must be cautious when working around these valves. Relieve pipeline pressure
and lockout the pumps before servicing the valve.
The flow from the pump opens the Disc (A10) and raises the Counterweight Arm (B19). If the valve is
equipped with an Air Cushion, the cylinder piston is pulled upward, drawing air freely into the cylinder
through the small flow control valve. If the valve is equipped with a lever & spring, the spring (B59) is
extended by the Lever Arm (B19) raising up.
When the pump is shut off, the decreased flow allows gravity to close the Disc (A10) towards the Body
Seat Ring (A05). For valves equipped with a lever & weight, the weight causes the disc close faster or
slower depending on its position along the lever. For valves equipped with an air cushion, the closure
speed can be dampened by the air cylinder (B20). As the Disc (A10) closes, the cylinder piston is
pushed downwards and the compressed air can only escape through the flow control valve on the
bottom of the cylinder. The exhausting air can be adjusted with the flow control valve to suit the best
performance for the installation. For valves equipped with a lever & spring, the stored energy in the
extended spring (B59) causes the disc to close in addition to weight of the disc (A10).
System static pressure (downstream of the check valve) keeps the disc (A10) and disc seat (A06)
closed and seated against the body seat (A05).
Closure Speed Control Adjustment (Valves with Lever & Weight)
•
Faster Disc closing - Move Counterweight away from the pivot shaft.
•
Slower Disc closing – Move Counterweight towards pivot shaft.
Closure Speed Control Adjustment (Valves with Air Cushion)
•
Increase cushioning - Turn adjusting screw of Flow Control Valve clockwise.
•
Decrease cushioning - Turn adjusting screw of Flow Control Valve counterclockwise
•
Faster Disc closing - Move Counterweight away from the pivot shaft.
•
Slower Disc closing – Move Counterweight towards pivot shaft.
October 2018
APCO CVS-250/250A Swing Check Valves
Page 9
DeZURIK
D12003