Fire Alarm Pull Station

A fire alarm pull station is an active fire protection device, usually wall-mounted, that, when activated, initiates an alarm on a fire alarm system. In its simplest form, the user activates the alarm by pulling the handle down, which completes a circuit and locks the handle in the activated position, and sending an alarm to the fire alarm control panel. Fire alarm pull station are often reset using a key, which allows the handle to go back up to its normal position. Single pull systems are simpler, but run a higher risk of accidental pulls.

Many fire alarm pull stations are single action and only require the user to pull down the handle. Other fire alarm pull stations are dual-action, and as such require the user to perform a second task before pulling down, such as lifting up or pushing in a panel on the station, or shattering a glass panel. The Fire-Lite BG-10 and the Cerberus Pyrotronics (Siemens) MS-501 are examples of this design. Perhaps the most recognizable pull station is the T-bar style pull. The style is so named because the handle is shaped like the letter "T". This style was first manufactured by Simplex, and is now manufactured by many other companies.

By Wikipedia