The Greystone Model CMD5B5000 Duct Carbon Monoxide Monitor / Detector, engineered and manufactured by Greystone Energy Systems Inc. in Moncton, New Brunswick, Canada, is an industry-leading gas detection instrument specifically designed for commercial building automation systems (BAS/BMS) and industrial HVAC ventilation safety monitoring.

Carbon Monoxide (CO) is an insidious, colorless, and odorless toxic gas generated by the incomplete combustion of fossil fuels (gasoline, diesel, natural gas, and propane) in internal combustion engines and industrial burners. Excessive CO buildup in enclosed areas presents severe acute toxicity hazards to building occupants. The CMD5B5000 continuously tracks CO levels within return air ductwork, allowing Building Automation Systems to dynamically activate variable-speed exhaust fans to purge contaminated air while avoiding unnecessary fan operation when CO concentrations remain well below safety thresholds.

Model Code Breakdown & Configuration (CMD5B5000):
- CMD5B: Advanced commercial Carbon Monoxide detector series featuring a high-stability electrochemical sensing element with an expected operating lifespan of 5 to 7 years in ambient air.
- 5: Duct-mount configuration enclosed in a robust ABS housing equipped with a factory-installed flow-through sampling probe.
- 000: Base analog model with No Alarm Relays and No Network Communications (pure analog output: 4-20 mA / 0-5 Vdc / 0-10 Vdc).

Key Engineering Features & Operational Advantages:
- High-Performance Electrochemical Sensing Technology: Delivers precision measurement with an accuracy of ±5 ppm or ±5% of reading, virtually eliminating cross-sensitivity to background humidity, alcohol vapors, and common refrigerant gases. The sensing element is designed as a field-replaceable modular component, drastically reducing long-term lifecycle maintenance costs.
- Menu-Selectable Measurement Ranges: Technicians can easily scale the measurement span directly via the front LCD screen menu to 0 - 100 ppm, 0 - 150 ppm, 0 - 300 ppm (factory default), 0 - 400 ppm, or 0 - 500 ppm, ensuring full conformity to local building codes and safety regulations.
- 3-in-1 Field-Selectable Analog Outputs: Provides user-selectable analog output signals: 4 to 20 mA (3-wire sourcing), 0 to 5 VDC, or 0 to 10 VDC. This ensures direct plug-and-play compatibility with all standard commercial DDC controllers, PLC inputs, and BMS platforms.
- Comprehensive On-Board Interface & Diagnostics: Standard features include a high-contrast backlit LCD screen displaying real-time ppm levels and setup menus, a tri-color status LED indicator, an integrated audible buzzer alarm (85 dB @ 10 ft) with programmable trip point/delay, and a front-panel test switch for system commissioning.
- Flow-Through Duct Sampling Probe: Utilizes an aerodynamic pitot-style probe that penetrates into the duct airstream, leveraging dynamic duct velocity pressure to draw representative air samples across the sensor chamber and vent them back into the airstream without external aspiration pumps.
- Rugged IP65 / NEMA 4X Flame-Retardant ABS Enclosure: Molded from grey UL94-5VB flame-retardant, UV-resistant ABS plastic sealed with an elastomeric perimeter gasket, protecting electronic components from airborne dust, mechanical moisture, and harsh mechanical room environments.

Typical Industrial Applications:
- Return air duct monitoring in commercial underground parking garages, residential parking structures, and enclosed transit stations.
- Continuous air quality control in highway and railway tunnels.
- Exhaust duct monitoring in warehouse logistics loading docks and indoor facilities operating propane- or diesel-powered forklifts.
- Safety ventilation interlocks in emergency standby generator rooms, boiler mechanical rooms, and engine maintenance bays.

• Manufacturer: Greystone Energy Systems Inc.
• Country of Origin: 100% Canada (Made in Canada)
• Product Line: CMD5B Series Commercial Carbon Monoxide Detectors
• Model Designation: CMD5B5000
• Sensing Element: Long-life Electrochemical Cell
• Sensor Lifespan: 5 to 7 years in ambient air (Field-replaceable cell)
• Sensing Ranges (Menu-Selectable): 0 - 100, 150, 300 (default), 400, or 500 ppm
• Measurement Accuracy: ±5 ppm or ±5% of reading (whichever is greater)
• Rated Accuracy Conditions: 0°C to 50°C (32°F to 122°F), 15% to 90% RH
• Response Time: < 30 seconds for 90% step change (T90 < 30s)
• Output Signals (Field-Selectable):
  - Current Output: 4 - 20 mA (3-wire sourcing)
  - Voltage Output: 0 - 5 Vdc or 0 - 10 Vdc (3-wire configuration)
• Output Drive Capability:
  - Current Output: 550 Ω maximum @ 24 Vdc
  - Voltage Output: 10 kΩ minimum
• On-Board Relays: None (No Relay - Option 000)
• Network Communications: None (Pure analog transmitter - Option 000)
• Display Panel: Backlit graphic LCD screen displaying real-time CO ppm levels and setup menus
• Audible Alarm: Built-in buzzer alarm (85 dB @ 10 ft), programmable setpoint and delay time
• Test Functionality: Front-panel momentary test switch and remote digital test input
• Visual Indicator: Multi-function status LED (Normal / Trouble / Alarm)
• Sampling Method: Flow-through sampling probe assembly for duct installation
• Power Supply Requirements: 24 Vac/dc ±20% (half-wave rectified)
• Current Consumption: 60 mA maximum @ 24 Vdc; 90 mA maximum @ 24 Vac
• Electrical Wiring: Screw terminal block accommodating 14 to 22 AWG wiring
• Enclosure Construction: Grey Polycarbonate / ABS, UL94-5VB flame-retardant, UV-resistant
• Ingress Protection Rating: IP65 / NEMA 4X (sealed against dust and water spray)
• Operating Conditions: -20°C to 50°C (-4°F to 122°F), 15% to 90% RH non-condensing
• Dimensions (Duct Model): 145 x 101 x 240 mm (5.7”W x 4”H x 9.5”D including probe)
• Regulatory Compliance: CE, RoHS, ISO 9001 certified manufacturing, meets OSHA & ASHRAE standards
• Instrument Weight: Approximately 320 g (0.7 lbs).