Pietro Fiorentini Aperflux 851 Regulator

The Aperflux 851 is a high-performance downstream gas pressure regulator designed for medium- and high-pressure applications. Self-actuated and pilot-operated, this robust regulator is ideal for use in natural gas distribution networks, as well as civil and industrial installations requiring precision, responsiveness, and safety. Its top-entry design allows for full maintenance without removing it from the pipeline, minimizing downtime and simplifying service.

This model is particularly well-suited for applications with rapid flow changes, such as ON-OFF burners or industrial processes. With a fail-to-open configuration, the Aperflux 851 provides reliable gas flow even in the event of pilot diaphragm failure or loss of sensing pressure.

Key Benefits

  • Pilot-operated, self-actuated regulator for accurate downstream pressure control

  • Top-entry design allows for easy in-line maintenance

  • Fail-open functionality ensures gas flow during pilot circuit failure

  • Fast response to operating condition changes, including sudden load variation

  • High turn-down ratio with precise pressure regulation

  • Compatible with various pilot systems and optional accessories

  • ANSI/UNI/DIN flanged connections in sizes 1” to 10”

 

Technical Highlights

  • Max Inlet Pressure: Up to 1,450 PSIG (depending on configuration)

  • Outlet Pressure Range: 11.6 – 1,073 PSIG, depending on pilot model

  • Min Differential Pressure: Recommended 7.25 PSIG (30 PSIG ideal)

  • Temperature Range: -40°F to +140°F with appropriate installation conditions

  • Accuracy Class (AC): Up to 1%

  • Lock-up Pressure (SG): 2.5%–5% depending on outlet pressure

  • Noise Reduction: Optional DB/851 silencer reduces sound at the point of throttling

  • Slam-Shut Devices: Available models SB/82 and HB/97 for over/under-pressure protection

  • Integrated Monitor: Optional PM/819 safety monitor ensures continuity if the main regulator fails
     

 

Common Applications

  • Natural gas gate stations

  • Industrial gas delivery systems

  • Civil gas distribution networks

  • Burner systems requiring fast pressure response
     

 

Optional Accessories

  • Slam shut valves (OPSO/UPSO)

  • In-line safety monitor