B18
Type EZR
5
Europe, Middle East and
Africa Only
Figure 4.
Type EZR Operational Schematic
OPERATION
Regulator
The Type EZR is a pilot-driven, diaphragm/plug regulator.
Tight shutoff is achieved by the diaphragm/plug pushing
against the slotted cage, the force of the closing spring and
the inlet pressure.
• Opening
As the flow increases, the outlet pressure P
d
decreases on the outlet side of the regulator and on
the pilot diaphragm.
Due to the force of the spring, the pilot opens.
The pilot flow increases, the pressure loss through the
pilot restrictor increases.
The modulated pressure P
m
decreases.
The force of the closing spring and that of the P
m
becomes inferior to that provoked by the P
u
, the
regulator OPENS.
• Closing
As the flow decreases, the P
d
increases outlet side of
the regulator.
The force of the pilot diaphragm is overcome by the force
of the spring, the pilot closes.
The pressure loss through the pilot restrictor decreases.
The force of the closing spring and that of the P
m
becomes superior to that provoked by the P
u
, the
regulator CLOSES.
Slam Shut
The pressure of the zone to be protected (generally the pipeline
on the outlet side of the regulator and after the slam shut) is
sensed by the safety manometric box (BMS).
If the pressure exceeds the set tripping pressure, the release
relay frees the valve plug.
Due to the force of the closing spring and the fluid (trying to
close), the valve plug closes on the orifice.
The gas flow is obstructed until the fault has been corrected
and the mechanism box manually rearmed.
To reopen the valve plug an equal pressure balance on inlet
and outlet sides of the regulator is required.
The mechanism box is rearmed after opening the
internal bypass.
Rearming and balancing are achieved at the same time.
INLET PRESSURE
MODULATED PRESSURE
OUTLET PRESSURE
