FOXBORO E69F-BI2

Description

Technical Specifications

1. Electrical Input Signal Parameters

• Standard Analog Input: 4–20 mA DC control loop signal
• Digital Communication Protocol: HART 5 / HART 7 superimposed bus communication (BI2 dual-channel bus interface)
• Operating Power Supply: 10.5 V DC to 42 V DC loop-powered, no separate external power supply required
• Input Loop Impedance: 250 Ω maximum load resistance

2. Pneumatic Output Performance

• Standard Pneumatic Output Span: 3–15 psig (0.2–1.0 bar) proportional to 4–20 mA input
• Supply Air Pressure Operating Range: 20–30 psig (1.4–2.1 bar) clean dry instrument air
• Output Air Capacity: 0.08 Nm³/h static air consumption
• Linear Accuracy: ±0.5% of full output span
• Repeatability Error: ±0.25% full span
• Hysteresis Deviation: ±0.5% full span
• Dead Band: 0.1% full span

3. Environmental & Mechanical Ratings

• Operating Ambient Temperature: -40°C to +85°C
• Storage Temperature: -50°C to +90°C
• Protection Enclosure Grade: IP65 dust and water ingress resistance
• Pneumatic Port Connection: 1/4″ NPT female thread for supply air and output air
• Electrical Conduit Port: 1/2″ NPT internal thread

4. Hazardous Area Certifications

• ATEX, IECEx, CSA, FM intrinsically safe Ex ia IIC T6 certification for Zone 0/1 flammable gas environments

Material Composition

• Main Enclosure Body: Die-cast aluminum alloy with anti-corrosion polyurethane coating
• Internal Pneumatic Flapper Nozzle Assembly: Stainless steel + PTFE low-friction sealing components
• Microprocessor Circuit Board: FR4 high-temperature flame retardant PCB with conformal protective coating
• Feedback Flexure Spring: High-stability beryllium copper alloy anti-fatigue spring strip
• Pneumatic Sealing O-rings: Viton fluororubber standard; EPDM optional for neutral gas media
• Terminal Block Insulation: Reinforced flame retardant PA66 plastic

Structural Features

• Field-mounted compact bolted enclosure design for direct pipeline or actuator bracket installation
• BI2 dual-channel HART bus interface circuit supports redundant dual communication channel configuration for critical safety control loops
• Stiff low-mass feedback flexure mechanical structure minimizes vibration and installation inclination measurement error
• Internal integrated surge voltage protection circuit for field wiring lightning interference resistance
• Separate isolated electrical terminal compartment and pneumatic amplification chamber to eliminate signal cross-interference
• External zero and span adjustment screws accessible without full enclosure disassembly for on-site calibration

Working Principle

1. DCS control system transmits 4–20 mA analog electrical setpoint signal to converter input terminals; HART digital diagnostic data superimposes on analog loop signal for BI2 bus communication module reading;
2. Input current generates proportional electromagnetic force on internal galvanometric coil assembly, pulls flapper nozzle mechanical assembly to adjust nozzle back pressure;
3. Back pressure drives two-stage pneumatic amplifier to output scaled 3–15 psig pneumatic pressure signal to valve actuator;
4. Beryllium copper feedback flexure spring generates reverse mechanical force to balance electromagnetic coil force, forms closed-loop proportional conversion to maintain linear input-output characteristic;
5. BI2 HART bus module collects internal converter temperature, zero drift and supply air pressure diagnostic data, transmits digital information back to FOXBORO I/A DCS asset management software for remote monitoring and calibration.

Function Features

• Linear 4–20 mA electrical to 3–15 psig pneumatic proportional signal conversion for pneumatic actuator control
• BI2 dual-channel HART communication enables remote range adjustment, zero calibration and equipment fault diagnosis without on-site access
• Split-range input signal configurable for dual-valve cascade control loop applications
• Built-in anti-vibration mechanical flexure design stable operation on high-vibration industrial pipelines
• Intrinsically safe circuit design certified for all flammable process hazardous area installation
• Conformal coated circuit board prevents moisture and corrosive gas damage to internal electronic components

Performance Advantages

1. ±0.5% full span linear accuracy ensures precise pneumatic valve stroke proportional control;
2. BI2 dual redundant HART communication channel improves critical control loop system availability;
3. Low-mass flapper nozzle mechanical design reduces pneumatic response delay to ≤200 ms;
4. IP65 sealed aluminum enclosure adapts to outdoor rain, dust and coastal salt spray corrosive environments;
5. Loop-powered design eliminates separate 24 V DC power supply wiring, reduces field installation wiring cost;
6. Compatible with all legacy pneumatic valve actuator systems, enables digital DCS upgrade without full valve replacement.

Applicable Industries

Chemical processing plants, oil refineries, natural gas transmission stations, power plant thermal control loops, pulp & paper manufacturing, food & beverage process control, pharmaceutical sterile production lines, water treatment industrial valve control.

Installation Requirements

1. Mounting bracket surface flatness ≤0.2 mm, mounting screw torque controlled at 6 N·m to avoid enclosure deformation;
2. Instrument supply air must be filtered to Class 3 clean air standard (particle ≤5 μm, dew point ≤-40°C) to prevent nozzle blockage;
3. Electrical wiring uses shielded twisted pair cable, cable shielding single-end grounded at DCS control cabinet;
4. Pneumatic tubing connection applies PTFE sealing tape on male threads, avoid over-winding tape entering internal amplifier chamber;
5. Install converter within 1 meter of pneumatic valve actuator to minimize pneumatic signal transmission delay from long tubing;
6. For intrinsically safe zone installation, use certified explosion-proof conduit fittings and barrier isolators per ATEX standard.

Usage Precautions

• Forbid supply air containing oil, liquid water or solid particles; nozzle blockage causes loss of proportional conversion function;
• Do not disassemble sealed enclosure in hazardous explosion-proof zones; disassembly invalidates intrinsic safety certification;
• Continuous ambient temperature exceeding +85°C accelerates fluororubber O-ring aging and generates pneumatic leakage;
• HART communication requires minimum loop supply voltage of 10.5 V DC; low voltage results in loss of digital diagnostic function;
• Regular zero and span calibration every 6 months to compensate flexure spring long-term fatigue drift;
• Avoid mounting converter adjacent to high-power frequency converters; electromagnetic noise distorts 4–20 mA input analog signal.