Valves tilting-disk check

Tilting-Disk Check Valves These valves (Fig. 10-160) may be installed in a horizontal line or in hnes in which the flow is vertically upward. The pivot point is located so that the distribution of pressure in the fluid handled speeds the closing but arrests slamming. Compared with swing checkvalves of the same size, pressure drop is less at low velocities but greater at high velocities. 

Closure at the instant of reversal of flow is most nearly attained in these valves. This timing of closure is not the whole solution to noise and shock at check valves. For example, if cessation of pressure at the inlet of a valve produces flashing of the decelerating stream downstream from the valve or if stoppage of flow is caused By a sudden closure of a valve some distance downstream from the check valve and the stoppage is followed by returning water hammer, slower closure may be necessary. For these applications, tilting-disk check valves are equipped with external dashpots. They are also available with low-cost insert Dodies. 

Assumed the following valve types are NOT used as Isolation valves Air Operated Dlaphram, Solenoid Operated, Pressure Relief Safety, Swing Check, or Tilting Disk Check. 

FIG. 10-163 a) Tilting-disk check valve, b) Dual-plate check valve. 

Closure at the instant of flow reversal is most nearly attained with tilting-disk, dual-plate, and specialty axial-flow check valves. However, quick closure is not the solution to all noise, shock, and water hammer problems. External dashpots are available when a controlled rate of closure is desired. Nonmetallic seats are also available. 

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