DeZURIK
APCO CVS-EDV Swing Check Valves
February 2016
Page 9
D12042
Operation
The flow from the pump opens the Disc (A10) and raises the counterweight assembly. If the valve is
equipped with an air cushion, the cylinder piston is pulled upward, drawing air freely into the Pneumatic
Cylinder (B68) through the Flow Control Valve (B67). If the 3-14” valve is equipped with a lever &
spring, the spring (B34) is extended by the Lever Arm Fabrication (B33) raising up. If the 16-30” valve is
equipped with a lever & spring, the spring (B86) is compressed by the Lever Arm Fabrication (B85)
raising up, lifting the Spring Shaft (B39), which in turn pulls the Spring Tension Plate (B79) which the
Spring (B86) is seated on.
When the pump is shut off, the decreased flow allows gravity to close the Disc (A10) towards the Body
Seat Ring (A5). For valves equipped with a lever & weight, the Counterweight (B60) causes the Disc
(A10) to close faster or slower depending on its position along the Counterweight Arm (B59). For valves
equipped with an air cushion, the closure speed can be dampened by the Pneumatic Cylinder (B68).
As the Disc (A10) closes, the cylinder piston is pushed downwards and the compressed air can only
escape through the Flow Control Valve (B67) on the bottom of the cylinder. The exhausting air can be
adjusted with the Flow Control Valve (B67) to suit the best performance for the installation. For 3-14”
valves equipped with a lever & spring, the stored energy in the extended spring (B34) causes the Disc
(A10) to close in addition to weight of the disc. For 16-30” valves equipped with a lever & spring, the
stored energy in the compressed spring (B86) causes the Disc (A10) to close in addition to weight of
the disc.
System static pressure (downstream of the swing check valve) keeps the Disc (A10) and Disc Seat
(A15) closed and seated against the Body Seat Ring (A5).
Closure Speed Control Adjustment (Valves with Lever & Weight)
•
Faster Disc closing - Move Counterweight (B60) away from the Shaft (A13).
•
Slower Disc closing – Move Counterweight (B60) towards Shaft (A13).
Closure Speed Control Adjustment (Valves with Air Cushion)
•
Increase cushioning - Turn adjusting screw of Flow Control Valve (B67) clockwise.
•
Decrease cushioning - Turn adjusting screw of Flow Control Valve (B67) counterclockwise.
Start-up Procedure
1. Ensure the Counterweight Arm (B59) is horizontal.
2. Throttle down mainline isolation valve (furnished by others) on discharge side of Swing Check
Valve to approximately 1/3 open to prevent severe slamming during initial pump shutdown
testing.
3. Position Counterweight (B60) midway on the lever and lock in place.
4. If valve has an Air Cushion: Unlock Flow Control Valve by turning Flow Control Valve lock nut
counter-clockwise. Turn Flow Control Valve adjustment screw two (2) turns counterclockwise
from fully close position. Lock Flow Control Valve by turning Flow Control Valve lock nut
clockwise. (See Figure 2.)
5. Start and stop pump and observe rate of closing.