Page 257 - Valve Selection Handbook

244 Valve Selection Handbook

the supporting edges of the holder do not deform the dome or the edges
of the dome. Any such deformation would affect the bursting pressure.
Rupture disc holders in flanged pipelines are commonly designed for
mounting between two flanges. This allows the rupture disc to be insert-
ed in the workshop under clean conditions. The holder parts, however,
are offered also with weld-neck connections. The user should be aware
that, with this construction, the insertion of the rupture disc has to be car-
ried out on site often under unfavorable conditions.
Clean-Sweep Assembly

The clean-sweep assembly, as shown in Figure 6-30, also known as
viscous Tee, is intended for applications in which viscous fluid could
cause product build-up and plugging of the flow passage. The sweeping
flow passage reduces this problem.

Figure 6-30. Clean-Sweep Design of
Rupture Disc Device, Incorporating
Forward-Domed Rupture Disc.
(Courtesy of Continental Disc
Corporation.)

Quick-Change Housings

To permit rapid replacement of burst rupture discs, a number of quick-
change devices have been developed such as shown in Figure 6-31 and
Figure 6-32. One of these devices requires change-over to be carried out
by hand. The second device is designed for change-over by means of a
pneumatic actuator.
Sealing of the positioned rupture disc is affected by O-rings mounted
in the change-over housing. Once the system pressure is restored, the O-
rings provide a powerful interlock between the change-over housing and
the rupture disc holders.