Volatile-Organic-Compounds

Supported Applications

The ACI VOC Series is an indoor air quality (IAQ) sensor designed to measure Total Volatile Organic Compounds (TVOC). The series utilizes a high-performance metal oxide semiconductor sensor to detect contaminants emitted from building materials, furnishings, office equipment, cleansers, and disinfectants. By measuring TVOC levels in the range of 0-1000 ppb (Isobutene), these transmitters communicate data back to Building Automation Systems (BAS) to assist users in adjusting ventilation for proper IAQ maintenance.

Operating Conditions & Performance

The series operates within an ambient temperature range of 32 to 122°F (0 to 50°C) and a humidity rating of 10 to 95% RH, non-condensing. Storage temperatures are specified from -4 to 140°F (-20 to 60°C). The sensor response time is less than 5 seconds, with a warm-up time of 15 minutes required for operation.

Enclosure protection ratings vary by configuration: IP30 for Room and Probe models, and IP65 for Duct models. All units feature ABS Plastic housings rated UL94V-0. The series requires a power supply of 16-28VAC or 16-35VDC with reverse polarity protection.

Configuration Options

The ACI VOC Series offers configurable mounting options, output signals, and interface features to accommodate different installation environments. The series supports the following capabilities:

• Housing Configurations: Room Mount (VOC-R), Duct Mount (VOC-D), and Probe configurations.
• Output Signals: Analog outputs of 4-20 mA (Default) or 0-10 VDC, alongside digital communication via Modbus RTU over EIA RS-485.
• Display & Control Options: The VOC-R-LCD variant includes an LCD display and a relay output. Other variants provide analog and digital outputs without the local display or relay.
• Relay Specifications (VOC-R-LCD): 1 SPDT, N.O., rated at 3A @ 30VDC and 3A @ 250VAC. The default Relay Trip Point is set to 230 ppb.
• Modbus RTU Configuration: Supports configurable slave addresses (Range: 1–255), baud rates of 4800 or 9600, and parity settings (NONE, ODD, EVEN). The protocol provides registers for Product Code, Equivalent CO2 value (ppm), VOC measured value (ppb), Software version, Working state, Relay state, LED state, and Control state.
• Electrical Connections: Screw Terminal Blocks accepting wire sizes from 16 AWG (1.31 mm²) to 22 AWG (0.33 mm²). Load resistance limits are 500 Ohms maximum for 4-20 mA and 2K Ohms minimum for 0-10 VDC.

Key Product Differences

The series is distinguished by three primary model configurations:

• VOC-R: Room Mount configuration providing 4-20 mA, 0-10 VDC, and Modbus RS-485 outputs.
• VOC-R-LCD: Room Mount configuration that adds an LCD display and a relay output to the standard analog and digital signals. This variant draws 50mA supply current compared to 33mA for non-LCD models.
• VOC-D: Duct Mount configuration providing 4-20 mA, 0-10 VDC, and Modbus RS-485 outputs with an IP65 enclosure rating. The duct model weighs approximately 270g compared to ~190g for the room mount.