City & Guilds Level 2 F-Gas Practice Exam 2026 – Complete Preparation Guide

A sight glass in a refrigeration system serves a vital role by allowing technicians to check for liquid refrigerant flow. It is a transparent component strategically placed in the refrigerant line that provides a visual indication of refrigerant status. When observing the sight glass, a technician can see whether there is liquid refrigerant present and if it is flowing correctly through the system.

This visibility is crucial for confirming that the refrigerant is not only moving but is also in the appropriate phase (liquid or vapor) for efficient operation. If the sight glass shows bubbles, it could indicate a low charge of refrigerant, which might lead to system inefficiencies or damage.

Thus, its primary function is to assist in the diagnostics and maintenance of the refrigeration system by verifying the presence and flow of liquid refrigerant.