67C Series
3
Principle of Operation
Downstream pressure is registered internally on the
lower side of the diaphragm. When the downstream
pressure is at or above the set pressure, the valve plug
is held against the orifice and there is no flow through
the regulator. When demand increases, downstream
pressure drops slightly allowing the spring to extend,
moving the stem down and the valve plug away from
the orifice. This allows flow through the regulator.
Internal Relief (Types 67CR, 67CSR,
67CFR, and 67CFSR)
If for some reason, outside of normal operating
conditions, the downstream pressure exceeds the set
point of the regulator, the force created by the
downstream pressure will lift the diaphragm until the
diaphragm is lifted off the relief seat. This allows flow
through the token relief. The relief valve on the
Type 67CR, 67CSR, 67CFR, or 67CFSR is an elastomer
plug that prevents leakage of air from the downstream
to atmosphere during normal operation, thereby
conserving plant air.
Smart Bleed™ Airset
In some cases, it is desired to exhaust downstream
pressure if inlet pressure is lost or drops below the
setpoint of the regulator. For example, if the regulator is
installed on equipment that at times has no flow
demand but is expected to backflow on loss of inlet
pressure. The Type 67CFR can be ordered with the
Smart Bleed™ option which includes an internal check
valve for this application. During operation, if inlet
pressure is lost, or decreases below the setpoint of the
regulator, the downstream pressure will back flow
upstream through the regulator and check valve. This
option eliminates the need for a fixed bleed downstream
of the regulator, thereby conserving plant air.
Overpressure Protection
The 67C Series regulators have maximum outlet
pressure ratings that are lower than their maximum
inlet pressure ratings. A pressure relieving or pressure
limiting device is needed if inlet pressure can exceed
the maximum outlet pressure rating.
INLET PRESSURE
OUTLET PRESSURE
ATMOSPHERIC PRESSURE
W7433
TYPE 67CFR OR 67CFSR
TYPE 67CF OR 67CFS
TYPE 67C OR 67CS
TYPE 67CR OR 67CSR
Figure 2. 67C Series Operational Schematics
SMART BLEED™ OPTION
TYPE 67CFR ONLY
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