Fisher 1098-EGR - Wide-Open Monitor (Figure 8); Installation; Startup

Types 1098-EGR and 1098H-EGR
13
5. Slowly open the downstream block valve.
6. Slowly close the bypass valve, if any.
NOTICE
Adjustment Recommendations for
Monitor Applications
Low amplitude/high frequency monitor trim oscillations
can occur if the monitor regulator pressure setting is
adjusted too closely to the working regulator pressure
setting and/or if the monitor pilot supply regulator
pressure setting is adjusted too closely to the monitor
regulator pressure setting. The monitor pressure
setting should be adjusted so it is at minimum 2
times the pilot proportional band pressure above the
working regulator pressure setting. The monitor pilot
supply pressure setting should be adjusted so it is at
minimum 5 psig (0,34 bar) plus the monitor minimum
differential pressure above the working regulator
pressure setting. These adjustments must be made
such that other governing pressure limits, such as
casing ratings, pilot maximum differential pressures, or
regulatory limits, are not exceeded.
Wide-Open Monitor (Figure 8)
Installation
1. For both the wide-open monitoring regulator and
the working regulator, perform the Standard
Single-Pilot Regulator Installation section
through step 6.
2. Connect the control line of the wide-open
monitoring regulator (Figure 8) to downstream
piping near the working regulator control line
connection. During normal operation the wide-
open monitoring regulator stands wide-open
with the pressure reduction being taken across
the working regulator. Only in case of working
regulator failure does the wide-open monitoring
regulator take control at its slightly higher setting.
Startup
Repeat this procedure in turn for each regulator in
the installation.
1. Slowly open the pilot supply line hand valve.
2. Slowly open the upstream block valve and
partially open the downstream block valve for
minimum ow.
Figure 8. Typical Wide-Open Monitor Installations
FLEXIBLE WIDE-OPEN MONITOR ARRANGEMENT THAT PERMITS
WIDE-OPEN MONITOR TO BE EITHER UPSTREAM OR DOWNSTREAM
MINIMUM PIPING WIDE-OPEN MONITOR ARRANGEMENT THAT
REQUIRES WIDE-OPEN MONITOR ALWAYS TO BE UPSTREAM
16A4296-A 16A4297-A
PILOT SUPPLY REGULATOR