Page 201 - Valve Selection Handbook

188 Valve Selection Handbook

device consists of Belleville disc springs. In combination with an auxil-
iary actuator for supplementary loading and/or lift assistance and a con-
trol system identical or similar to the one shown in Figure 5-24, these
valves are used in conventional and nuclear power plants.

Oscillation Dampers

Oscillation dampers are friction devices that act on the stem carrying
the disc. Figure 5-14, Figure 5-27, and Figure 5-28 show three types of
oscillation dampers in combination with direct-loaded pressure relief
valves. The device shown in Figure 5-14 has already been described
under the subject of "Relief Valves."
The damping device of the pressure relief valve shown in Figure 5-27
relies on dry friction for damping oscillations, and uses lens-shaped fric-

Figure 5-27. Pressure Relief Valve with Dry Friction Oscillation Damper. (Courtesy of
Bopp & Reuther.)