Model Number Explanation

05704: System 57 / 5704 series (fire & gas detection)

A: Standard assembly

0144: 4‑channel control card, catalytic input

Technical Specifications

Sensor Type: Catalytic bead (pellistor) flammable gas sensors

Channels: 4 independent, isolated channels

Sensor Drive: Constant current, 90–315 mA (1 mA steps)

Max Drive Voltage: 10 V

Max Line Resistance: 40 Ω (including sensor @ 200 mA)

Signal Range: 15–300 mV full‑scale

Bridge Imbalance: ±100 mV (max offset from center)

Power Supply: 18–32 VDC (24 VDC nominal, backplane‑fed)

Power Consumption: 8.5 W typical; 12.8 W max (@ 200 mA/channel)

Display: Backlit 4‑part LCD (bar graph + digital + alphanumeric)

Indicators: Per‑channel LEDs (A1/A2/A3/Fault/Inhibit); Power/Attn LEDs

Form Factor: 3U × 1” (25 mm) wide, 19” subrack mount

Weight: ~165 g

Operating Temp: −20°C to +60°C

Certifications: CE, TUV, UL 508, CSA

Key Features

Catalytic sensor support: Optimized for pellistor‑type flammable gas detectors

4‑channel monitoring: Independent alarm configuration for each channel

3‑level alarms: A1 (low), A2 (high), A3 (fault) per channel

Electronic calibration: Bridge balance and gain adjustment (no pots)

Fault detection: Open/short circuit, sensor bead failure

Hot‑swap capable: Insert/remove without rack shutdown

Local display: Real‑time gas concentration, peak hold, sensor status

Remote functions: Inhibit, remote alarm reset via backplane

Applications

System Role: Primary monitoring card for flammable gas detection

Industries: Oil & gas, petrochemical, power, pharmaceuticals, water treatment

Gases Monitored: Methane, propane, butane, hydrogen, and other flammable gases

Use Cases:

Fixed gas detection systems in hazardous areas

Plant safety and explosion protection

Leak monitoring in pipelines and storage facilities

Integration with DCS/PLC via relay outputs or Modbus

Compatibility

System: Honeywell System 57 (5704 fire/gas racks; 5701 gas racks)

Backplane: Standard 19” subrack backplane (24 VDC + data)

Replacement: Direct drop‑in; obsolete (EOL)—available as refurbished/used

Sibling Card: 05704‑A‑0145 (4–20 mA input version)

Critical Notes

This card is for catalytic sensors only (not 4–20 mA or infrared types).

It is not a relay card—it processes sensor inputs and drives local alarms; use 05704‑A‑0121 for relay outputs.