Shutdown For Both Single-Regulator And Monitoring Installations; Operation - Fisher EZR Instruction Manual

Type EZR
Table 5. 161 and 161EB Series Pilot
Adjustment Recommendations
RECOMMENDED
PILOT TYPE 112 RESTRIcTOR
TYPE SETTInGS FOR LOW
FLOW OPERATIOn
161/161H Restrictor Setting of "5"
Series Pilots or greater
161EB Restrictor Setting of "5"
Series Pilots or greater
Note: Higher Type 112 restrictor settings will increase proportional band. Adjustment of
the Type 112 restrictor will also cause a shift in setpoint. Setpoint should be checked
and adjusted following restrictor setting adjustment.
Table 6. Type 161AY/161AYM Pilot
Adjustment Recommendations
RECOMMENDED
TYPE 112 RECOMMENDED
PILOT RESTRIcTOR ORIFIcE SIZE(S)
TYPE SETTInGS FOR FOR LOW FLOW
LOW FLOW

OPERATIOn

161AY
Restrictor Setting (2,38 or 3,18 mm)
Series
of "5" or greater (3/32-inch (2,38 mm)
Pilots
Note: Higher Type 112 restrictor settings will increase proportional band. Adjustment of
the Type 112 restrictor will also cause a shift in setpoint. Setpoint should be checked
and adjusted following restrictor setting adjustment.
Table 7. Type PRX Pilot Adjustment Recommendations
RECOMMENDED
TYPE PRx RESTRIcTOR
PILOT
AND DAMPER SCREw
TYPE
SETTInGS FOR LOW
FLOW OPERATIOn
Restrictor Screw
- 1 turn out
(counterclockwise) from
fully seated for most
low flows
- 2-1/2 turns out (for flows
PRX/120 and
less than 5% of maximum)
PRX/120-AP Series
Damper Screw
- Fully out
(counterclockwise) from
seated for most low flows
- One turn out (for flows
less than 5% of maximum)
Note: Counterclockwise adjustment of the Type PRX restrictor screw will increase
proportional band. Adjustment of the restrictor screw will also cause a shift in setpoint.
Setpoint should be checked and adjusted following restrictor screw adjustment.
12
TYPE 112 RESTRIcTOR
SETTINGS TO AVOID LOw
FLOW OPERATIOn
Restrictor Setting of "2" or
less if continuous flows are
expected to be less than 5% of
maximum capacity
Restrictor Setting of "2" or
less if continuous flows are
expected to be less than 5% of
maximum capacity
TYPE 112
RESTRIcTOR
SETTINGS AND
ORIFIcE SIZES TO
OPERATIOn AVOID LOw FLOw
OPERATIOn
Restrictor Setting
3/32 or 1/8-inch of "2" or less if
continuous flows are
expected to be less
is standard) than 5% of
maximum capacity
TYPE PRx
RESTRICTOR AND
DAMPER SCREw
SETTInGS TO
AVOID LOw FLOw
OPERATIOn
Restrictor Screw
– Fully seated
(clockwise) or full out
(counterclockwise)
Damper Screw
– Full in (clockwise)
maximum performance by decreasing the restrictor
setting for tighter control (increased opening speed,
decreased closing speed); or increasing the restrictor
setting for maximum stability (decreased opening speed,
increased closing speed). A lower setting also provides
a narrower proportional band for better accuracy. The
"8" position has the largest flow, is most stable, and
easiest for startup, however, using the "8" position
is not necessary. The "0" setting has the smallest
(minimum) flow passage; at no point of rotation will the
Type 112 restrictor be completely shut off. After initial
adjustment, the restrictor does not need to be adjusted
for maintenance or startup.
Pilot Adjustment – (For Low Flow
Applications Only)
For stable, low flow operation, other considerations
besides pilot settings should also be addressed.
Installation of an oversized regulator may make low flow
operation difficult. When possible, a smaller-sized
Type EZR should be installed. During design of a
regulator installation, the downstream piping volume
should be maximized. Control lines should not be located
in or near piping sections that may experience turbulent
flow, such as elbows or swages. Larger diameter control
lines are also recommended in low flow conditions. The
larger control lines are less restrictive and will reduce pilot
exhaust bleed backpressure to the pilot that may cause
instability. Separate sense and exhaust lines may also
help at low flow conditions. This feature is provided on
the PRX Series, Types 161M, 161HM, 161EBM, and
161AYM pilots. Control line taps should be located in
straight pipe; several pipeline diameters (8 to 10 of largest
piping on outlet) downstream of the regulator. These
guidelines are not mandatory but have been used to
improve station stability at low flow in some systems.
Shutdown for Both Single-Regulator and
Monitoring Installations
WARnInG
!
If pilot supply pressure is shut down
first, the downstream system may be
subjected to full inlet pressure.
1. If the pilot setting must be disturbed, be sure to
keep some tension on the spring. This will prevent
trapping inlet pressure during blow down.
2. Close the valves shown in Figure 3 or 4, in the
following order:
a. Inlet block valve
b. Outlet block valve
c. Control line valve(s), if used
3. Open the vent valves to depressurize the system.