Abstract: A concealed sprinkler includes a body that defines an outlet, a seal that seals the outlet, an activation element coupled with the seal, a housing that defines a chamber around the activation element, a cover plate removably coupled with the housing, and a wall coupled with or extending from the cover plate to direct air flow to the activation element. The activation element changes from a first state to a second state responsive to a fire condition to allow the seal to be displaced from the outlet. The cover plate is removably coupled with the housing such that a duration of time between decoupling of the cover plate from the housing responsive to the fire condition and changing of the activation element from the first state to the second state responsive to the fire condition is less than a threshold duration of time.

Abstract: A concealed sprinkler can include a body that defines an outlet, a seal that seals the outlet, an activation element coupled with the seal, a housing, a cover plate, and a wall. The activation element changes from a first state to a second state responsive to a fire condition to allow the seal to be displaced from the outlet. The housing extends from a first housing end that extends from the body to a second housing end, and defines a chamber around the activation element. The cover plate is coupled with the second housing end. The wall extends towards the activation element to form an air flow channel to the activation element adjacent to the wall. At least one of the cover plate and the wall are removably coupled with the body.

Abstract: Antifreezes, which include glycerol or a mixture of alkylene glycol and glycerol, water and an organic acid salt, are provided. Exemplary antifreezes include at least about 45 vol. % water, greater than 48 to about 55 vol. % glycerol, 0.1 to 1.75 wt. % of a salt of an organic acid having one or more carboxylic acid groups, and optionally, one or more buffers. Wet sprinkler systems containing the antifreeze, methods of controlling a fire using the antifreeze and methods of preventing a wet sprinkler system from freezing are also provided.