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EZH and EZHSO Series

V

TYPE PRX

R

S

V

TYPE PRX

TYPE SA/2

B

S B

L

R

A

L

M

A

M TYPE SA/2

M1164

TYPE EZH

INLET PRESSURE OUTLET PRESSURE ATMOSPHERIC PRESSURE LOADING PRESSURE INTERMEDIATE PRESSURE PILOT SUPPLY PRESSURE

TYPE PRX: S - BLEED PORT B - SUPPLY PORT L - LOADING PORT A - SENSING PORT

TYPE EZHSO

TYPE SA/2: V - SENSING PORT R - PILOT SUPPLY PORT M - INLET PORT

Figure 5. Wide-Open Monitoring System Operational Schematic

Wide-Open Monitoring System (Figure 5) There are two types of wide-open monitoring systems: upstream and downstream. The difference between upstream and downstream monitoring is that the functions of the regulators are reversed. Systems can be changed from upstream to downstream monitoring, and vice-versa, by simply reversing the setpoints of the two regulators. The decision to use either an upstream or downstream monitoring system is largely a matter of personal preference or company policy. In normal operation of a wide-open configuration, the working regulator controls the system’s outlet pressure. With a higher outlet pressure setting, the monitor regulator senses a pressure lower than

its setpoint and tries to increase outlet pressure by going wide-open. If the working regulator fails, the monitoring regulator assumes control and holds the outlet pressure at its outlet pressure setting. Figure 5 shows an upstream wide-open monitor Type EZH (fail to close) and a downstream active regulator Type EZHSO (fail to open). In this installation, if the Type EZHSO regulator no longer controls downstream pressure, it will remain open, letting the Type EZH monitor regulator take control of the downstream pressure. If the Type EZH should fail, the monitor regulator will go closed and protect against overpressure to the downstream system.

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EZH~EZHSO Regulator Instruction Manual  

Fisher Controls instruction manual, courtesy of RMC Process Controls & Filtration, Inc. & www.RegulatorParts.com. Repair kits, orifices, dis...

EZH~EZHSO Regulator Instruction Manual  

Fisher Controls instruction manual, courtesy of RMC Process Controls & Filtration, Inc. & www.RegulatorParts.com. Repair kits, orifices, dis...

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