Fisher EZR Instruction Manual page 8

Type EZR
in a straight run of pipe. Do not place a control
line connection in a turbulent area, such
as in or directly downstream of a swage or elbow.
Significant restrictions in the control line can prevent
proper pressure registration. When using a hand
valve, it should be a full flow valve, such as a full
port ball valve. With a Type 161EBM or 161AYM
pilot, run a downstream exhaust bleed line
to the downstream bleed line connection in the pilot
body assembly.
8. Good piping practices usually require swaging
up to larger downstream piping to obtain
reasonable downstream fluid velocity.
wide-Open Monitor Installations
1. Follow the procedures in the All Installations
section, and then continue with step 2 of this section.
2. Pilot supply for the downstream monitoring
regulator must be obtained between the
two regulators as shown in Figure 4. With
this arrangement, the downstream monitoring
regulator diaphragm changes position with every
load change. For sizing purposes, add the
minimum differential pressure for each
regulator together to establish the required
pressure drop across the station. System lock-up
pressure is equal to the setpoint of the working
regulator pilot when a Type 161EBM or a
Type 161AYM is used on an upstream regulator,
otherwise lock-up pressure is equal to monitor pilot
lock-up pressure.
working Monitor Installations
On working monitor installations, the working monitor
regulator is always upstream and acts as a first-stage
regulator through the working pilot during normal
operation. This arrangement allows the working
monitor's performance to be observed at all times.
Then, should the second-stage regulator fail open,
the working monitor regulator assumes the entire
pressure reduction function of the system through the
monitoring pilot.
Use the following procedure when installing a working
monitor system.
1. Follow the procedures in the All Installations
section, and then continue with step 2 of
this section.
2. Pilot supply pressure for the downstream
Type EZR regulator must be made directly
upstream of the Type EZR using
intermediate pressure.
8
3. Significant restrictions in the control line can
prevent proper pressure registration. Connect
the control line a minimum of 8 to 10 pipe
diameters downstream of the regulator in a
straight run of pipe. Do not make the control line
connection in a turbulent area, such as in or
directly downstream of a swage or elbow. When
used, a hand valve should be a full flow valve such
as a full port ball valve.
4. Table 9 gives the spread between normal
distribution pressure and the minimum pressure
at which the monitor pilot can be set to take over
if the working regulator fails open.
5. Table 4 shows the minimum differential pressure
requirements across an individual regulator.
Because this application uses a first-stage
and second-stage pressure reduction, add the
minimum differential pressure for each regulator
together to establish the required pressure drop
across the station. Do not exceed maximum pilot
ratings given in Table 3.
Type EZR/PRX working Monitor
On working monitor installations, the working monitor
regulator is always upstream and acts as a first-stage
regulator through the working pilot during normal
operation. This arrangement allows the working
monitor's performance to be observed at all times.
Then, should the second-stage regulator fail open,
the working monitor regulator assumes the entire
pressure reduction function of the system through the
monitoring pilot. Use the following procedure when
installing a working monitor system.
As shown in Figure 5, run a supply pressure line
(use 3/8 NPT outer diameter tubing or larger) from the
upstream pipeline to the inlet (Port S) of the upstream
Type PRX-120 pilot. Install a Type 252 pilot supply
filter upstream of the pilot, if needed, to keep the
supply source from clogging the restrictor in the pilot.
Inspect and clean this filter regularly to make sure it
has not been plugged.
Connect the loading port (Port L) of the upstream
Type PRX-120 pilot to the bonnet of the upstream
Type EZR regulator. Connect the "B" port of the upstream
Type PRX-120 pilot to the "S" port of the upstream
Type PRX-125 pilot. Connect the "A" port (located on the
underside of the pilot) of the upstream Type PRX-120 pilot
to the intermediate pressure between the first and second
Type EZR regulators as shown in Figure 5.
The "L" port of the upstream Type PRX-125 pilot
is plugged. Connect the "B" port of upstream
Type PRX-125 pilot to the intermediate pressure
between the first and second Type EZR regulators.