The document describes the Pietro Fiorentini Serie FEX Low-Pressure Gas Regulator, a self-operated dual-stage regulator designed for gaseous fluids.
Function Description:
The Serie FEX regulator is designed to adjust gas pressure to a pre-set value. It operates in two stages:
- First Regulation Stage: Reduces the upstream pressure to an intermediate pressure.
- Second Regulation Stage: Further adjusts the intermediate pressure to the desired downstream pressure, as required by the user.
This dual-stage regulation ensures stable and accurate pressure control.
Important Technical Specifications:
The Serie FEX is available in three standard models based on nominal flow rate:
- FEX50: 50 m³/h
- FEX75: 75 m³/h
- FEX100: 100 m³/h
Key technical features include:
- Design Pressure (DP): 0.86 MPa (8.6 bar)
- Inlet Pressure Range: 0.01 - 0.86 Mbar (0.1 - 8.6 bar)
- Regulator Capacity: 1765 - 3530 ft³/h (50 - 100 m³/h)
- Adjustment Range of Downstream Pressure:
- BP Version: 1.3 - 9.9 kPa (13 - 99 mbar)
- TR Version: 10 - 35 kPa (100 - 350 mbar)
- Accuracy Class (AC): 10
- Shut-off Overpressure (SG): 20
- Operating Ambient Temperature:
- Standard version: -20°C to +60°C
- Low temperature version: -40°C to +60°C
- Permissible Gas Temperature:
- Standard version: -10°C to +60°C
- Low temperature version: -20°C to +60°C
The regulator is suitable for gaseous fluids such as natural gas, LPG, and non-corrosive gases. It is designed to comply with UNI 11655:2016 and UNI EN 16129:2013 standards.
Usage Features:
The Serie FEX can be installed directly on user's gas meters, rising pillars, and burners. It is intended for use in pressure control stations, commercial premises, and industrial plants. The equipment can also be used with inert gases, subject to manufacturer verification.
Several configurations are available:
- Inlet/Outlet Connections: Modular connections are available, including G 1" EN ISO 228/1 for inlet and G 1" 1/2 EN ISO 228/1 for outlet (in-line or square pattern). Other options include flat swivel joints (NF E29-533, NF E29-536) and NPT connections (ASME B1.20.1).
- Safety Diaphragm Version: Guarantees service continuity and adjusted pressure control in case of working diaphragm breakage, allowing identification through controlled gas leakage (< 30 l/h).
- Thermal Valve Version: Cuts off gas supply if ambient temperature reaches 160°C. This version requires specific fittings from Pietro Fiorentini S.p.A.
- Indoor Installation Version: Designed for indoor use, subject to local regulations and requiring proper ventilation.
- Underground Version: Features special surface guards and components for installation in underground wells. This version is not suitable for operation if completely covered by earth or debris. A drum assembly is available for underground versions, which must be in a horizontal position with the camera facing the ground.
- Low Temperature Version: Identified by a specific plate, ensuring correct operation down to -40°C ambient temperature and -20°C gas temperature.
The regulator includes safety devices:
- Slam-Shut Valve: For minimum and maximum downstream pressure, it remains open during normal operation and automatically closes the gas flow if downstream pressure exceeds calibration values. Resetting requires eliminating the fault that caused the trip.
- Relief Valve: Automatically discharges gas into the atmosphere through an exhaust conveyor if downstream pressure exceeds a pre-set value, and returns to shut-off position when pressure drops. The tripping pressure of the relief valve is lower than that of the slam-shut valve.
- Pressure Outlet: Standard (0.5 bar max operating pressure) or Peterson model (10 bar max operating pressure) outlets are available for in-field checks of safety devices.
Maintenance Features:
The manual emphasizes that the equipment does not require periodic checks and maintenance procedures under normal operating conditions. However, functional checks of safety devices are crucial and must be performed by qualified technicians.
Functional Checks:
- Pds (adjusted pressure) check: Involves opening an external pressure source tap and verifying the pds value is within ±10% of the nameplate value.
- Internal sealing check: Requires closing the external pressure source tap and ensuring downstream pressure remains stable for about 2 minutes.
- Slam-shut device tripping check: Involves increasing/decreasing external pressure at specific rates (2 mbar/s for BP, 5 mbar/s for MP) until the slam-shut device trips, then verifying the tripping value is within ±15% of the nameplate value. The discharge conveyor can be partially plugged to facilitate pressure increase downstream of the gearbox if the relief valve opens prematurely.
Installation:
- Installation must be carried out by qualified technicians familiar with safety regulations and lifting equipment.
- The equipment must be installed in compliance with UNI EN 12186:2014 or UNI EN 12279:2007 standards for gas pressure reduction stations.
- The flow direction arrow on the body must align with the gas flow.
- Connections must be properly tightened to prevent leakage.
- The equipment should be protected from blows and impacts.
- Avoid mounting positions with the outlet flow facing upwards when using LPG.
- The instruction manual, declaration of conformity, and test certificate are integral parts of the equipment and must accompany it throughout its service life.
Adjustments:
- All regulators are factory-calibrated by Pietro Fiorentini S.p.A. No further adjustments are typically required.
- Minor ±10% calibration changes are possible within specified spring ranges.
- The relief valve pressure does not need adjustment.
- Any unauthorized changes to the equipment without Pietro Fiorentini S.p.A.'s approval will void the warranty.
Uninstallation and Disposal:
- Uninstallation and disposal must be performed by qualified personnel in areas free from explosive ignition sources.
- Before uninstallation, the fluid in the reduction line and inside the equipment must be completely drained.
- The equipment must be made safe by disconnecting it from any power supply.
- Components must be sorted by material type for separate collection and sent to specialized companies for recycling. Materials include nitrile rubber (diaphragm, O-rings), plastic (caps, discs), steel (springs), and aluminum alloy (equipment body, lids, seat).
Storage:
- Maximum storage period is 5 years.
- Storage conditions: temperature not above 40°C, humidity not above 70%, away from radiation and light sources (UNI ISO 2230:2009).
- Equipment stored beyond 5 years must be scrapped.
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