Emerson EZR Series Pressure Reducing Regulator Instruction Manual download pdf (Page 5)

EZR

OPERATION

REGULATOR

The 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 Pa 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 Pm decreases.

The force of the closing spring and that of the Pm becomes inferior to

that provoked by the Pe, the regulator OPENS.

• Closing

As the flow decreases, the Pa 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 Pm becomes superior

to that provoked by the Pe, 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.

B18

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Emerson EZR Series Pressure Reducing Regulator Instruction Manual Page 5