Elaborate on the proper calibration and usage procedures for a multi-gas meter used for atmospheric monitoring in confined spaces, including actions to take upon encountering specific alarm conditions.

The proper calibration and usage of a multi-gas meter are essential for ensuring accurate atmospheric monitoring in confined spaces. A multi-gas meter is an instrument designed to detect various gases, such as oxygen, flammable gases, and toxic substances like hydrogen sulfide and carbon monoxide. Calibration is a critical process that confirms the meter's sensors are functioning correctly and providing accurate readings. Improper calibration can lead to inaccurate readings, thus potentially exposing workers to hazardous conditions. Calibration is usually performed in two stages: bump testing and full calibration. A bump test is a quick check to ensure that the meter's sensors respond to a known concentration of gas. It involves exposing the sensors to a gas mixture and ensuring that the readings fall within an acceptable range. This test is typically performed before each day of use, or before each entry into a confined space. A full calibration is a more detailed process which calibrates all the sensors and adjusts them for optimal performance. It involves using a calibration gas with a specific concentration and adjusting the meter's readings to match this concentration, ensuring accuracy across the detection range. Th....