Fisher EZL Instruction Manual page 5

January 2008
Type EZL Upstream or Downstream Wide-Open Monitor
P590 SERIES
PILOT SUPPLY
FILTER
E0948
INLET PRESSURE
OUTLET PRESSURE
INLET PRESSURE
LOADING PRESSURE
OUTLET PRESSURE
INTERMEDIATE PRESSURE
LOADING PRESSURE
ATMOSPHERIC PRESSURE
INTERMEDIATE PRESSURE
ATMOSPHERIC PRESSURE
Working Monitoring Regulators (Figure 5)
In a working monitoring system, the upstream regulator
requires two pilots and it is always the monitoring
regulator. The additional pilot permits the monitoring
regulator to act as a series regulator to control an
intermediate pressure during normal operation. In this
way, both units are always operating and can be easily
checked for proper operation.
In normal operation, the working regulator controls
the outlet pressure of the system. The monitoring
regulator's working pilot controls the intermediate
pressure and the monitoring pilot senses the system's
outlet pressure. If the working regulator fails, the
monitoring pilot will sense the increase in outlet
pressure and take control.
The working regulator must be rated
for the maximum allowable operating
pressure of the system because this will
be its inlet pressure if the monitoring
TYPE 67C PILOT
SUPPLY REGULATOR
TYPE 6352 PILOT
P590 SERIES PILOT
SUPPLY FILTER
TYPE EZL MAIN VALVE
INLET PRESSURE
OUTLET PRESSURE
LOADING PRESSURE
INTERMEDIATE PRESSURE
ATMOSPHERIC PRESSURE
Figure 4. Wide-Open Monitoring System Operational Schematic
Note
TYPE 6352 PILOT
TYPE EZL MAIN VALVE
regulator fails. Also, the outlet pressure
rating of the monitoring pilot, and any
other components that are exposed to
the intermediate pressure must be rated
for full inlet pressure.
Working monitor installations require a Type EZL
main valve with a working pilot and a monitoring pilot
for the upstream regulator and a Type EZL with the
appropriate pilot for the downstream regulator.
Adjustment
Adjusting the monitor regulator is similar to
adjusting the main regulator. Monitor setpoints are
set slightly higher than the main regulator. However,
the value of this difference cannot be determined in
advance, as it depends on the particular characteristics
of each application.
Type EZL
Type EZL
5