Data Sheet

Bulletin 71.1:CS200
7
CS200 Series with Internal Relief
Refer to Figure 3. The option for internal relief is offered
on the Types CS200 and CS205 and is standard on the
Type CS206. Internal relief is used to help minimize
overpressure. Any outlet pressure above the start-to-
discharge point of the non-adjustable relief spring moves
the diaphragm off of the relief seat, allowing excess
pressure to discharge through the vent. For approximate
start-to-discharge values, see Table 5. If emergency
conditions should exist that prevent normal operation
of the regulator or internal relief valve, the relief valve
stem acts as a secondary travel stop contacting the
underside of the closing cap and stopping the upward
travel of the relief seat. Since the diaphragm continues
to rise as downstream pressure builds, the diaphragm
lifts off of the relief seat to provide relief operation. See
Figures 5 through 8 for Relief Capacity data.
Type CS205 with Secondary Seat™
Protection
Refer to Figure 4. The Type CS205 provides
Secondary Seat Protection. As downstream demand
decreases and downstream pressure rises to the
regulator pressure lock-up value, the regulator will
lock up. If, however, damage has occurred to the
primary disk, to the primary orice’s seating surface,
or debris has become lodged between the primary
disk and primary orice, the outlet pressure will
continue to rise. This additional pressure causes the
primary disk to apply additional force to the orice
seating surface, which causes the secondary seating
surface to move toward the secondary disk or sealing
surface. If downstream demand decreases to zero,
then the secondary seating surface will contact the
sealing surface to provide lockup. Refer to Table 6
for approximate lock-up values provided by the
Secondary Seat.
Type CS206 Secondary Seat Protection
with Bleed
The Type CS206 provides small bleed to the
downstream system as an indication that the
Secondary Seat is providing lockup. In the event that
the primary orice and disk can not provide lockup, the
secondary seating surface will move into contact with a
metal disk. This metal to metal interface will allow a small
amount of gas to bleed downstream thereby increasing
outlet pressure until the Internal relief valve begins to
discharge gas to the atmosphere. The odor of this
discharged gas provides an indication that the regulator
is relying on the Secondary Seat for overpressure
protection. See Table 6 for the Downstream Pressure
Buildup of the Internal relief acting in conjunction with the
Type CS206 Secondary Seat Assembly.
Types CS205 and CS206 Secondary Seat
Protection Limitations
Secondary Seat Protection does not provide additional
overpressure protection in the event the secondary
seating surface or disk is damaged by debris or
contamination in the pipeline or from conditions that
would cause the regulator to go wide open. When
selecting Secondary Seat Protection option, it is
recommended that:
• Other additional overpressure protection methods
be added in the downstream system as discussed
in the section on Overpressure Protection; and
• An annual downstream lock-up pressure test be
done to determine if the Secondary Seat Protection
option is operating and functional
Installation
The CS200 Series regulators may be installed in
any position. However, the spring case vent should
be pointed downward. If gas escaping through the
CS200 Series internal relief valve could constitute
a hazard, the spring case vent must be piped to a
location where escaping gas will not be hazardous.
If the vented gas will be piped to another location,
use obstruction-free tubing or piping at least equal in
size to the vent, and the end of the vent pipe must be
protected from anything that might restrict or clog it.
Dimensions are shown in Figure 10.
Overpressure Protection
The CS200 Series regulators have outlet pressure
ratings lower than the inlet pressure ratings. Additional
downstream overpressure protection is needed and
sized for wide-open capacity discharge if the actual
inlet pressure exceeds the outlet pressure rating.