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High – Medium Pressure Gas Regulators

Advanced pressure regulation solutions for high and medium pressure gas transmission and distribution.

High pressure gas regulators reduce gas from transmission pressure to the level a city gate, compressor station, power plant or industry needs. This page lists 15 Pietro Fiorentini models.

The 8 pilot operated pressure reducing regulators reach design pressures up to 102 bar and accuracy down to AC 1; the 7 direct operated, spring loaded regulators reach 250 bar. Sizes: 1/4 inch to 12 inch, ASME B16.5 flanges to Class 1500, for gas networks and industry in Saudi Arabia and the GCC: the UAE, Qatar, Kuwait, Bahrain and Oman.

Pilot Operated

Aperflux 101 pilot operated high pressure gas regulator with pilot on a flanged body, fail open, by Pietro Fiorentini
Pilot Operated

Aperflux 101

Pilot operated regulator for high-medium pressure gas transmission and distribution applications.

  • Design Pressure: Up to 85 bar
  • Sizes: 2", 3", 4"
  • Classification: Fail Open (EN 334)
  • Connections: 300 RF, 600 RF, RTJ
View Details
Aperflux 851 pilot operated high pressure gas regulator, flanged body with pilot, hydrogen ready, by Pietro Fiorentini H2 Ready
Pilot Operated

Aperflux 851

Hydrogen-ready pilot operated regulator for high-medium pressure applications.

  • Design Pressure: Up to 102 bar
  • Sizes: 1", 2", 3", 4", 6", 8", 10"
  • Classification: Fail Open (EN 334)
  • Connections: 150 RF, 300 RF, 600 RF, PN 16, PN 25, PN 40
View Details
ASX 176 pilot operated high pressure gas regulator, flanged, fail close, by Pietro Fiorentini
Pilot Operated

ASX 176

High accuracy pilot operated regulator for gas transmission and distribution networks.

  • Design Pressure: Up to 102 bar
  • Sizes: 1", 2", 3", 4", 6"
  • Classification: Fail Close (EN 334)
  • Connections: 300 RF, 600 RF, RTJ
View Details
ASX 176/FO fail open pilot operated high pressure gas regulator with pilot tubing, flanged, by Pietro Fiorentini
Pilot Operated

ASX 176/FO

Pilot operated regulator with fail-open function for high-medium pressure applications.

  • Design Pressure: Up to 102 bar
  • Sizes: 1", 2", 3", 4", 6"
  • Classification: Fail Open (EN 334)
  • Connections: 300 RF, 600 RF, RTJ
View Details
Dixi AP pilot operated high pressure gas regulator, 1 inch flanged body with pilot, fail close, by Pietro Fiorentini H2 Ready
Pilot Operated

Dixi AP

Pilot operated regulator for high-medium pressure gas networks.

  • Design Pressure: Up to 85 bar
  • Sizes: 1"
  • Classification: Fail Close (EN 334)
  • Connections: 150 RF, 300 RF, 600 RF, RTJ, PN 16
View Details
Reflux 819 pilot operated high pressure gas regulator, flanged, hydrogen ready, by Pietro Fiorentini H2 Ready
Pilot Operated

Reflux 819

Hydrogen-compatible pilot operated regulator for gas transmission applications.

  • Design Pressure: Up to 102 bar
  • Sizes: 1", 2", 3", 4", 6", 8", 10", 12"
  • Classification: Fail Close / Fail Open (EN 334)
  • Connections: 150 RF, 300 RF, 600 RF, PN 16
View Details
Reflux 819/FO fail open pilot operated high pressure gas regulator, flanged, by Pietro Fiorentini H2 Ready
Pilot Operated

Reflux 819/FO

Pilot operated regulator with fail-open function for high-medium pressure applications.

  • Design Pressure: Up to 102 bar
  • Sizes: 1", 2", 3", 4", 6", 8", 10", 12"
  • Classification: Fail Open (EN 334)
  • Connections: 150 RF, 300 RF, 600 RF, PN 16
View Details
Terval AP pilot operated high pressure gas regulator, three-in-one body with monitor and slam shut, by Pietro Fiorentini H2 Ready
Pilot Operated

Terval AP

Pilot operated regulator for high-medium pressure gas distribution applications.

  • Design Pressure: Up to 102 bar
  • Sizes: 1", 2", 3", 4"
  • Classification: Fail Close (EN 334)
  • Connections: 300 RF, 600 RF, RTJ
View Details

Direct Operated

ATF anti-freeze direct operated gas pressure regulator with pressure gauge by Pietro Fiorentini
Direct Operated

ATF Anti-Freeze

Direct operated anti-freeze regulator for medium pressure gas distribution networks.

  • Design Pressure: Up to 220 bar
  • Sizes: 1/4"
  • Classification: Fail Open (EN 334)
  • Connections: NPT
View Details
Dival 160 AP direct operated high pressure gas regulator, 1 inch flanged body, by Pietro Fiorentini
Direct Operated

Dival 160 AP

Direct operated regulator for high-medium pressure applications.

  • Design Pressure: Up to 85 bar
  • Sizes: 1"
  • Classification: Fail Open (EN 334)
  • Connections: 300 RF, 600 RF, RTJ
View Details
FT 518 lever operated direct acting high pressure gas regulator, top entry design, by Pietro Fiorentini
Direct Operated

FT 518

Direct operated regulator for high-medium pressure gas applications.

  • Design Pressure: Up to 69.4 bar
  • Sizes: 3/4", 1", 2"
  • Connections: Threaded NPT or flanged
View Details
Norflux direct operated high pressure gas regulator, 2 inch flanged body, fail open, by Pietro Fiorentini H2 Ready
Direct Operated

Norflux

Direct operated regulator for high-medium pressure gas distribution.

  • Design Pressure: Up to 100 bar
  • Sizes: 2"
  • Classification: Fail Open (EN 334)
  • Connections: 300 RF, 600 RF, RTJ
View Details
Staflux 185 direct operated high pressure gas regulator, flanged, fail open, by Pietro Fiorentini
Direct Operated

Staflux 185

Direct operated regulator with diaphragm control for high-medium pressure applications.

  • Design Pressure: Up to 100 bar
  • Sizes: 1", 2", 3"
  • Classification: Fail Open (EN 334)
  • Connections: 300 RF, 600 RF, RTJ
View Details
Staflux 187 direct operated 250 bar gas pressure regulator by Pietro Fiorentini
Direct Operated

Staflux 187

Direct operated regulator for high-medium pressure gas applications.

  • Design Pressure: Up to 250 bar
  • Sizes: 1"
  • Classification: Fail Open (EN 334)
  • Connections: 1500 RF, RTJ
View Details
Staflux Mini compact direct operated 250 bar gas pressure regulator, fail close, by Pietro Fiorentini H2 Ready
Direct Operated

Staflux Mini

Compact direct operated regulator for high-medium pressure gas applications.

  • Design Pressure: Up to 250 bar
  • Sizes: 1"
  • Classification: Fail Close (EN 334)
  • Connections: 1500 RF, threaded NPT
View Details

How to choose a high pressure gas regulator

Begin with the maximum inlet pressure and the outlet set point, then size for flow.

  • Inlet and outlet pressure

    Most pilot operated models here accept up to 100 bar inlet and control outlet pressures up to 74 bar: the ASX 176 and Reflux 819 both cover 0.8 to 100 bar inlet.

  • Above 100 bar inlet

    Choose a direct operated model: the Staflux 187 takes 2 to 250 bar inlet and the Staflux Mini 5 to 250 bar, both in 1 inch with Class 1500 connections.

  • Outlet range

    Check the outlet range too: the Dival 160 AP accepts up to 85 bar but delivers only 0.85 to 4.5 bar.

  • Size for flow (Cg, K1)

    Pietro Fiorentini sizes each regulator from its flow rate coefficient (Cg) and form factor (K1) per EN 334; with an in-line monitor, the technical brochures advise reducing the active regulator's Cg by about 20%.

  • Body size by flow

    Large city gate runs can use the Reflux 819 (1 to 12 inch) or the Aperflux 851 (1 to 10 inch); smaller flows suit 1 inch bodies such as the Dixi AP.

Fail mode, safety devices and connections

  • Fail open or fail close

    Under EN 334 a regulator is fail open or fail close. Fail open: Aperflux 101, ASX 176/FO, Reflux 819/FO. Fail close: ASX 176, Dixi AP, Terval AP, Staflux Mini.

  • Monitor and slam shut

    A working regulator is often protected by a monitor, set at a higher pressure, and by a slam shut valve; many models take these on the same body.

  • Built-in options

    The Reflux 819 accepts the PM/819 monitor and SB/82 or HB/97 slam shut, and the Terval AP combines regulator, monitor and slam shut in one body.

  • Connections

    Most models have Class 300 or 600 RF or RTJ flanges; the FT 518 has threaded NPT ends.

  • Freezing pilot gas

    Where pilot or instrument gas could freeze after pressure reduction, the ATF Anti-Freeze avoids gas pre-heating.

  • What to send us

    For a station in Jubail, Dammam or Doha, send us your data and we will check the options.

Frequently asked questions

Which regulator handles inlet pressure above 100 bar?

Choose a direct operated model. The Staflux 187 accepts 2 to 250 bar inlet, controls 1 to 75 bar outlet and is fail open. The Staflux Mini covers 5 to 250 bar inlet and 4 to 75 bar outlet and is fail close. Both are 1 inch. The ATF Anti-Freeze has a 220 bar design pressure for low-flow duties such as feeding pilots and pneumatic instruments.

What does fail open and fail close mean for a gas pressure regulator (EN 334)?

EN 334 classifies how a regulator reacts if it fails: a fail open regulator reacts by opening, a fail close regulator by closing. With a fail open regulator the supply stays on, so downstream protection comes from a monitor or slam shut valve. A fail close regulator shuts the line itself. On this page the ASX 176/FO and Reflux 819/FO are true fail open plug and seat designs, while the ASX 176 and Dixi AP are fail close.

How does a working monitor protect a city gate station from overpressure?

An in-line monitor is a second regulator, usually installed upstream of the active regulator. The two are mechanically almost identical, but the monitor is set at a higher pressure and stays fully open in normal service. If the active regulator fails and the outlet pressure rises to the monitor set point, the monitor takes control. Monitors can also be built into the regulator body, such as the PM/819 on the Reflux 819, which keeps the line compact.

Which high pressure regulators are hydrogen ready?

The models marked H2 Ready on this page are intended for NG-H2 blending. The flyers of the Aperflux 851, Reflux 819/FO and Terval AP state compatibility with 20% hydrogen blending, with higher blending on request. Other models, such as the Aperflux 101 and Staflux 185, are available in specific versions for full hydrogen or blending. Tell us the planned hydrogen share when you request a quotation.

Guides: Pilot Operated vs Direct Operated Regulator: Key Differences · Gas Pressure Regulators: How They Work, Types and How to Choose

Need Help Selecting the Right Regulator?

Our technical team can help you choose the optimal high-medium pressure regulator for your application requirements.

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