Self-testing fire sensing device

A method, comprising:

• determining a baseline rate at which an aerosol density level decreases within a fire sensing device;
• comparing a subsequently measured rate at which the aerosol density level decreases within the fire sensing device with the baseline rate;
• determining a time when the rate at which the aerosol density level within the fire sensing device will decrease at a particular rate based on the comparison;
• and
• determining the fire sensing device requires maintenance at the determined time.

A system, comprising:

• a fire sensing device, comprising a controller configured to conduct one or more self-tests within the fire sensing device by:
• determining a baseline rate at which an aerosol density level decreases within the fire sensing device;
• comparing a measured rate at which the aerosol density level decreases within the fire sensing device with the baseline rate;
• and
• determining a time at which the fire sensing device will require maintenance based on the comparison of the measured rate at which the aerosol density level decreases with the baseline rate.