Final answer:
The color of the low-side gauge of a manifold set is blue, and it is used to measure suction pressure in HVAC/R systems.
Step-by-step explanation:
The color of the low-side gauge of a manifold set is typically blue. The manifold gauge set is a crucial tool used in the field of heating, ventilation, air-conditioning, and refrigeration (HVAC/R). It consists of a manifold with two hand valves and two pressure gauges. The low-side gauge, which is blue, measures suction pressure and is used for the low-pressure side of an air conditioning system. Conversely, the high-side gauge is usually colored red and is used to measure discharge or head pressure on the high-pressure side. This color coding helps technicians prevent errors while connecting the manifold set to an HVAC system.