If you’re a healthcare facility with a medical air compressor system, then you have a carbon monoxide or CO monitor on that system.  NFPA 99 requires that the CO monitor be calibrated at least annually or more often if recommended by the manufacturer (NFPA 99 2012 ed. 5.1.14.4.7(2) or 2018 ed. 5.1.14.5.7(2)).  The “gotcha” moment here is with the second part of that statement regarding the manufacturer’s recommendations.  The chart below lists some of the manufacturers recommendations for CO monitors commonly used on medical air compressor systems.  As you will see, every single one of them require calibration more often than the annual frequency mentioned in NFPA 99.

Manufacturer:Model:Frequency of Calibration per O&M:Cal Gas Required:
Amico / KWJA310 / A316Every 3 months100 PPM
EnmetCO-GuardEvery 3 months20 PPM
EnmetMedAir 2200Every 3 months20 PPM
EnmetISA-RAL-MEvery 3 months20 PPM
GFGABL-50 / RAM-50Every month20 PPM
GFGABL-4021 / RAM-4021 / 4021-DPXEvery month20 PPM
GFG4035 / 4035-22Every month20 PPM

Be sure to identify what type of CO monitor each of your medical air systems has on it and take steps to ensure you have documentation showing you are calibrating the monitor(s) per the manufacturer’s recommendations.  Keep in mind, if you have multiple medical air systems, you might have different monitors on those systems and they may have different calibration schedules.