Principle Of Operation - Emerson Tartarini FL Series Instruction Manual

TYPE PRX/120
TYPE SA/2
M
R
B
V
M1212_08/2018
inLET PRESSURE
OUTLET PRESSURE
INLET PRESSURE
aTMOSPhERiC PRESSURE
OUTLET PRESSURE
LOaDing PRESSURE
ATMOSPHERIC PRESSURE
inTERMEDiaTE PRESSURE
LOADING PRESSURE
PiLOT SUPPLY PRESSURE
INTERMEDIATE PRESSURE
PILOT SUPPLY PRESSURE

Principle of Operation

The pilot-operated Type FL (Figure 2) uses inlet
pressure as the operating medium, which is reduced
through pilot operation to load the actuator diaphragm.
Outlet pressure opposes loading pressure in the
actuator and also opposes the pilot control spring.
When outlet pressure drops below the setting of the
pilot control spring, pilot control spring force on the
pilot diaphragm opens the pilot valve plug, providing
additional loading pressure to the actuator diaphragm.
This diaphragm loading pressure opens the main valve
plug, supplying the required flow to the downstream
system. Any excess loading pressure on the actuator
diaphragm escapes downstream through the exhaust
restriction in the pilot.
When the gas demand in the downstream system
has been satisfied, the outlet pressure increases.
The increased pressure is transmitted through the
downstream control line and acts on the pilot diaphragm.
This pressure exceeds the pilot spring setting and moves
the diaphragm, closing the orifice. The loading pressure
TYPE
PRX/131
S
S
B
L L
A
A
TYPE PRX:
S - BLEED PORT
B - SUPPLY PORT
L - LOaDing PORT
a - SEnSing PORT
TYPE FL WiDE-OPEn MOniTOR WiTh TYPE PRX/131 QUiCK DUMP PiLOT
Figure 3. Installation Schematics (continued)
TYPE PRX/120
TYPE SA/2
M
S
R
B
L
V A
TYPE Sa/2:
V - SEnSing PORT
R - PiLOT SEnSing PORT
M - inLET PORT
acting on the main diaphragm bleeds to the downstream
system through the exhaust restriction in the pilot.
Figure 2 also shows a Type FL regulator with a
Type PRX/131 pilot included. The Type PRX/131 pilot is
referred to as a quick dump or booster pilot as it helps
to boost the closing speed. When the Type PRX/131
pilot detects an increase in downstream pressure, it
allows the Type FL regulator to release pressure off the
downstream side of the diaphragm so it closes faster.
Type Sa/2 Pilot Supply Filter Regulator
The PRX Series pilot are usually used together
with the Type SA/2 pilot supply filter regulator. The
Type SA/2 acts as a pressure stabilizer that provides a
constant supply pressure to the PRX Series pilot that
is approximately 45 psi / 3.1 bar over set pressure.
The Type SA/2 has an integral 5 micron filter. The
integral filter acts only as an emergency filter; gas
must be cleaned upstream of the regulator.
Type FL
5