What kind of liquid fills a glass bulb sprinkler?

Glass bulb sprinklers are designed to utilize a special liquid that expands when heated, triggering the sprinkler's activation in case of a fire. The liquid used in these bulbs is specifically chosen for its ability to remain effective and responsive within a certain temperature range while having a low freeze point. This ensures that the sprinkler operates optimally in various environmental conditions, particularly in areas that may experience colder temperatures.

The non-freezing liquid serves a dual purpose: it not only fills the glass bulb but also ensures that the sprinkler system remains functional even in conditions where freezing might compromise the operation of other types of liquids. Choosing a liquid that doesn't freeze at lower temperatures is crucial for maintaining readiness in an emergency. Therefore, non-freezing liquid is essential for the reliability of glass bulb sprinklers, ensuring they can activate properly when needed.