Page 251 - Valve Selection Handbook
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238 Valve Selection Handbook
The disc is made in sizes DN25 (NFS 1) through DN 600 (NFS 24).
The burst pressure range covers the lowest burst pressures up to 120 barg
(1800 psig) at 22°C (72°F) operating temperature. Maximum operating
temperature is 550°C (1000°F).
The advantages of this disc are zero manufacturing range, burst toler-
ance is down to plus/minus 2%, operating ratio is as high as 95%, and it
may be employed in liquid-full systems (consult manufacturer).
Two-way rupture disc. In the case of domed two-way rupture discs,
such as shown in Figure 6-22 and Figure 6-23, flow in one direction is
forward acting and in the other direction reverse acting.
The rupture disc shown in Figure 6-22 consists of three components.
The upper perforated component is a forward-domed rupture disc that is
provided with a partial circumferential score line and protects the pressure
system against overpressure. The second element is a PTFE seal member
that fails under overpressure and subnormal pressure conditions. The third
element is represented by a reverse-buckling bar disc that fails on subnor-
mal pressure. On rupture of the upper component, the buckling bars will
fail in tension and allow the disc to open in unity with the upper disc.
Figure 6-22. Two-Way Rupture Disc Incorporating Buckling Bars. (Courtesy of Rembe
GmbH.)