Parking Garage Carbon Monoxide Sensor Calibration
Critical procedure for verifying and adjusting fixed CO sensor output to ensure accurate detection of exhaust accumulation, timely activation of mechanical ventilation, and compliance with CSA 6.19 and ASHRAE 62.1.
To verify and adjust the output of fixed CO sensors to match a known reference concentration, ensuring accurate detection of exhaust accumulation and timely activation of mechanical ventilation systems, thereby maintaining airborne CO levels below 25 ppm (long-term) and 50 ppm (short-term) thresholds.
Applies to all electrochemical cell and metal-oxide semiconductor (MOS) type CO sensors permanently installed in the [Facility Name] parking garage ventilation control system, specifically units connected to the Building Automation System (BAS). Does not include portable gas monitors or sensors installed in mechanical rooms unrelated to exhaust monitoring.
- Lockout/Tagout ventilation fan control circuits if working within 1m of moving parts (belts, couplings). De-energize sensor power loop only if hot-swap is required.
- Wear nitrile gloves to prevent skin oils from contaminating sensor membranes. Safety glasses required when handling calibration gas cylinders.
- Calibration gas (50 ppm CO in air) is under pressure (2000 psi). Secure cylinder upright. Do not vent calibration gas in enclosed space without continuous air exchange.
- Ensure garage ventilation system is functional and set to occupied mode before introducing calibration gas.
- NIST-traceable certified calibration gas cylinder (50 ppm CO, balance air) with C-10 fitting
- Calibration gas regulator (0.5 - 1.0 LPM flow rate)
- Non-absorbent PTFE or Tygon tubing (1/8" ID)
- Calibration cap / magnetic wand (specific to sensor manufacturer: Honeywell, MSA, or RKI)
- Multi-turn potentiometer adjustment tool (ceramic or nylon)
- BAS client interface (laptop with BACnet/IP or Modbus connection)
- Digital multimeter (DMM) for milliamp (4-20mA) loop verification