HI-FOG® sprinklers are typically used in systems where the thermal activation of the sprinkler activates the discharge. The heat-sensitive glass bulb bursts at the given temperature (five standard options ranging from 57 to 141°C), and this releases the spool valve, which allows the high pressure water to flow through the micro-nozzles.

HI-FOG® sprinklers consist of the sprinkler body, spool valve, micro-nozzles and a heat-sensitive glass bulb. Each sprinkler is equipped with a 300 µm strainer to protect against clogging. Most HI-FOG® sprinklers are made of brass and plated with chrome or nickel. Other finishes, such as gold, are also available.