What type of monitor is specifically required under ASHRAE standard 15?

The correct choice is a refrigerant monitor with alarming capability, as specified under ASHRAE standard 15. This standard deals with the safety of refrigeration systems and requires the installation of a refrigerant monitoring device in areas where refrigerants may leak, particularly in areas that could pose a safety risk to individuals.

Such monitors are essential for detecting the presence of refrigerants in the air to prevent potentially harmful exposure. They are equipped with alarming capabilities to alert personnel when refrigerant levels exceed permissible limits, thus ensuring timely evacuation or remedial action if necessary. Employing this type of monitor helps to maintain safe working environments in facilities that utilize refrigeration systems.

Other types of monitors, such as non-refrigerant specific monitors or air quality monitors, do not meet the specific requirements laid out in ASHRAE standard 15 since they aren't designed to specifically detect refrigerant leaks or provide specific alarms related to refrigerant presence. Multi-gas detectors can sometimes detect refrigerants, but they are not required under the scope of ASHRAE standard 15, which directly emphasizes the need for refrigerant-specific monitors with the ability to alarm.