Asense-Duct

Supported Applications

The ACI aSENSE Duct series is designed to monitor carbon dioxide (CO₂) levels in industrial, commercial, school, and office environments. Utilizing single beam non-dispersive infrared (NDIR) technology, the transmitter measures CO₂ concentration as an indicator of indoor air quality for climate control applications. The device integrates with Building Automation or Demand Control Ventilation Systems to manage ventilation based on occupancy indicators.

Operating Conditions & Performance

The series operates within a temperature range of 32°F to 122°F (0°C to 50°C) and relative humidity from 0 to 85% RH Non-condensing. The standard CO₂ sensing range is 0 to 2000 ppm, with an extended factory-set or programmable option for ranges up to 10,000 ppm. Temperature measurement spans -4 to 140°F (-20 to 60°C). Accuracy specifications are ±30 ppm and ±3% of reading for CO₂ (±5% of reading above 2,000 ppm) and ±1.8°F (1°C) for temperature. Repeatability is rated at ±20 ppm ±1% of measured value.

Response time is less than 10 seconds @ 30 cc / minimum flow rate or less than 3 minutes diffusion time. The unit requires a warm-up period of less than 5 minutes to reach full specifications (15 minutes). Annual zero drift is specified as <± 0.3% of measurement range. Pressure deviation impacts accuracy by +1.6% per 0.145 psi (1 kPa) from normal pressure, where 1 Atmosphere equals 14.7 psi (1.013 KPa). The sensor life exceeds 15 years.

Configuration Options

The aSENSE Duct series offers configurable analog outputs and relay control options to suit various integration needs. Power is supplied via 24 VAC/VDC ±20%; 50/60 Hz, or 10.5 to 40 VDC maximum (Half-wave rectified), with power consumption under 1W.

Outputs and Control

• Output 1 (CO₂): Configurable for 0/2 to 10V, 0/4 to 20 mA, or a direct 0 to 2000 ppm signal.
• Output 2 (Temperature): Provides 0/2 to 10V, 0/4 to 20 mA, or 32 to 122°F (0 to 50°C).
• Relay Output: N.O. or N.C., rated at 0.5A @ 125 VAC; 1A @ 24 VDC.

The relay trip point is factory set to 1000 ppm with a deadband/hysteresis of 100 ppm (factory set). Relay durability is rated for a minimum of 5,000,000 mechanical operations and 100,000 electrical operations under load. Outputs are field selectable via onboard jumpers or configured using the UIP5 software with a TTL-232R-3V3 programming cable.

Construction and Environment

The enclosure features an IP65 rating. The duct box is constructed from PC & ABS blend (Flammability Rating UL94V-0), the cover uses Makrolon® 6555 plastic (Flammability Rating UL94V-0), and the pipe utilizes a PC & ABS blend (Flammability Rating UL94V-0). The unit weighs 0.812 lbs (0.368 kg) with overall dimensions of (H) 5.95" (151.9 mm) x (W) 3.33" (84.6 mm) x (D) 1.85" (47 mm). Electrical connections are made via 0.00232 in² (1.5 mm²) screw terminals.

Key Product Differences

The series includes two primary model configurations distinguished by the presence of a display:

• ASENSE-D-REL: CO₂, Duct Mount with Relay output and selectable analog outputs (0-10 VDC or 0-20 mA; field-selectable 4-20 mA or 2-10 VDC).
• ASENSE-D-LCD-REL: Includes a 4-digit, 7-segment LCD with ppm indicator for local readout and error indication. This model also features the relay and selectable analog outputs.

The ASENSE series utilizes the Senseair ABC (Automatic Baseline Correction) algorithm to eliminate manual calibration requirements. Note that accuracy is defined after a minimum of three (3) ABC periods, where one period equals 8 days of continuous operation. For buildings occupied 24 hours/day or those unable to drop CO₂ levels to 400 ppm weekly, the ABC function must be turned off.