Installation and Operation Manual
Domus HF - Pressure Regulating Valve
MI-23
Elaborado
Verificado / Aprovado
CSQ
Data
Revisão
Página
JJ
VBL
JM
15/12/17
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9 de 19
3.1 –PILOT AND INTERNAL FILTER
The series G31F and G33F pilot are simple diaphragm type.
It is responsible for exact loading pressure for the pressure regulator open or close, under normal operating conditions,
based on equilibrium existence between the regulating spring force and the outlet pressure of sensing line.
The pressure under the pilot diaphragm, outlet pressure regulator, forces the pilot diaphragm set upward. In this
condition, the shutter shaft move upward due of shutter spring until contact the pilot seat, closing the pilot gas passage.
When there is gas consumption, this pressure under the diaphragm decrease and the regulating spring has enough
force to move the shaft downward and open the pilot. In this condition, the pressure in the upper chamber of main valve will
be higher than the pressure under the diaphragm of main valve, and allow that the main valve open to feed the process
gas demand.
The G31F and G33F pilot is composed of internal filter element, which objective is to avoid that particles present in the
process gas damage the shutter, seat of diaphragm set.
In case of damage in the shutter or pilot seat can occur a small gas passage resulting in increase in outlet pressure.
Then, in case of pressure relief during absence of gas consumption or shutting down of slam shut valve these parts shall
be inspected through inspection cover.
The pilot diaphragm rupture result in pressure equalization under and above the diaphragm, resulting in possible pilot
opening, since the regulating spring force moves the diaphragm set downward to open the pilot.
Shutter
Spring
Shutter
Seat
Filter
Element
Adjuting
Spring
Relief
Adjusting
Screw
Diaphragm
Shaft
