The Macurco CD-6B is a Carbon Dioxide (CO2) detector, controller, and transducer designed for use in non-hazardous commercial and industrial settings where CO2 is stored or used, such as bars, restaurants, and breweries. It is capable of displaying CO2 concentrations from 0 to 5.0% volume with a resolution of 0.01% volume. The device is ETL Listed to UL 61010-1 and Certified to CSA C22.2#61010-1.

Function Description:

The CD-6B provides CO2 detection and automatic ventilation control. It features three selectable dry contact alarm relays, an audible buzzer, and a 4-digit LED digital display. The device is a supervised system, meaning any internal detector problem will activate the buzzer. It performs an internal self-test cycle for the first minute after power-up or reapplication, during which the indicator LED flashes green. The display will flash "Cd6b" and the firmware version for the first 2 seconds, then count down from 60 to 0 (if the display is "On"). Upon completion of the power-up test, the indicator LED turns solid green.

Important Technical Specifications:

Gas Detected: Carbon Dioxide (CO2)
Measurement Range: 0 to 5.0% vol. CO2
Display Resolution: 0.01% vol.
Sensor Type: Non-dispersive infrared (NDIR) sensor
Sensor Life Expectancy: 15 years (typical)
Power: 12 to 24 VAC or 12 to 32 VDC (3 W max)
Current Consumption (max @ 24 VDC): 50 mA (three relays in alarm), 40 mA (two relays in alarm), 30 mA (one relay only in alarm), 25 mA (standby)
Alarm Relays: Three dry contact relays (SPST for Alarm 1 & 2, SPDT for Alarm 3)
- Load Capacity: Up to 2.0 A, 240 VAC or 30 VDC
- Configuration: Alarm 1 & 2 selectable N.O. (default) or N.C.; Alarm 3 can be wired N.O. or N.C.
- Alarm Level Settings: Selectable from "diS" (disabled), 0.25, 0.50 (default for Alarm 1), 1.00, 1.50 (default for Alarm 2), 2.00, 2.50, 3.00 (default for Alarm 3), 3.50, 4.00, 4.50, 5.00% vol.
Relay Latching: Selectable "Off" or "On" (default "Off" for Alarm 1 & 2, "On" for Alarm 3)
Alarm 1 Time Weighted Average (TWA) Option: On (default) or Off
Alarm 1 Trouble Condition Engagement: On or Off (default "Off")
Buzzer: 85 dBA at 10cm, settable to "Off" or "On" (default)
Digital Display: 4-digit LED, settable to "Off" or "On" (default)
Operating Environment: Temperature 32°F to 121°F (0°C to 50°C), Humidity 0 to 85% RH non-condensing, Pressure 1 ATM ± 20%
Storage Environment: Temperature 0°F to 125°F (-18°C to 52°C), Humidity 0 to 99% RH non-condensing
Dimensions: 4 1/2 x 4 x 2 1/8 in. (11.4 X 11.4 X 5.3 cm)
Shipping Weight: 1 pound (0.45 kg)
Mounting: On a standard 4x4 electrical box (not included)

Usage Features:

The CD-6B offers user-configurable settings for its alarm relays, buzzer, and digital display.

Alarm Priority: Awareness Alarm (0.50% vol., non-configurable) has the lowest priority, followed by Alarm 1, Alarm 2, Alarm 3, and Trouble Fault (highest priority).
Display Options: The digital display can be set to "On" or "Off." When "On," it shows current CO2 concentration, flashes gas readings during Awareness Alarms, and alternates between "ALrX" and gas readings for Alarm 1, 2, or 3. When "Off," it only shows "ALrX" for alarms and nothing for clean air or Awareness Alarms.
Relay Latching: When set to "On," an activated relay remains active even if gas concentration drops below the alarm level, requiring a power interruption or "ENTER/TEST" button press to un-latch. When "Off," relays deactivate once gas concentration falls below the set point.
Trouble Fan Setting (tFS): If enabled, Alarm 1 Relay activates during a trouble condition.
Automatic Background Calibration (Abc): An optional feature that regularly sets the clean air level.
Calibration Period (CAL): When Abc is "Off," users can set a calibration interval (3, 6, 12, or 24 months). The unit will indicate "calibration due" within one month of the period and "calibration overdue" if the period is exceeded.

Maintenance Features:

The CD-6B is designed for low maintenance, primarily due to its long-life NDIR sensor.

Calibration:
- If Abc is enabled, the unit maintains accuracy if exposed to a "clean air reference value" at least once per week.
- If Abc is disabled, manual calibration is required at least annually using the Macurco CD6B-FCK calibration kit.
- The device can issue calibration reminders via the "CAL" setting.
- A field calibration procedure is detailed, involving connecting a 400 ppm CO2 gas cylinder and following on-screen prompts.
- The unit records "Time Since Calibration" (tSC), displayed as Y.MM (years.months), visible when Abc is "Off."
Sensor Life Reset: The sensor life can be extended by one year. This option is available only once. After resetting, the unit will still show a "t 80" error (calibration overdue) and requires calibration before use.
On-Board Diagnostics: Continuously monitors critical functions. If a problem is detected, the unit enters a fail-safe/error mode, displaying an error code ("t XX" or "tYYY"), flashing the green status LED, and chirping the buzzer intermittently.
End-of-Life Signal: After 15 years, the sensor activates an end-of-life signal ("t200" error code). This signal can be silenced for 48 hours by pressing "ENTER/TEST" or temporarily cycling power. The silence function is available for 29 days, after which the unit must be replaced.
Cleaning: External surfaces can be cleaned with a damp cloth and mild detergent. A vacuum cleaner with a soft brush can remove dust from under the cover. Avoid harsh cleaning materials and compressed air on the sensor.

Macurco CD-6B - Page 79

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