Turning it the other way and then activating the pull allows a silent test to be done in which the station's mechanical parts are checked to ensure proper function. Turning the switch one way causes the notification appliances to sound continuously (or in the case of single-stroke bells, ding once). System tests could be conducted in one of two ways: In a coded pull station, there is either a test hole on the front (usually activated with an Allen wrench) or a test switch on the inside. If there was, they would evacuate the building and call the fire department.
After finding the location of the pull, they would check to see if there is a real fire.
When the station was pulled, the security officers in the building would look up 5-3-1 in a master list of codes. For example, consider a pull station in the fourth floor elevator lobby of an office building with a code of 5-3-1. This code was used by building security to determine where the alarm was originating from. The teeth would push up on a contact, which would open and close a circuit, pulsing the code to the bells or horns. The gears would turn a small wheel with a specific number of teeth, which determined the coding. They had a gear mechanism that was wound up when the station was pulled, and (unlike modern pull stations) the handle did not stay down. These coded pull stations were much bigger than modern pulls and had a code wheel in them. In the past, pull stations controlled the entire system. Manual pull stations that require two hand motions, such as lift up and pull down, or push in and pull down, have since replaced the break-glass and single-action models in many modern installations. Early strategies to cope with this problem included requiring the operator to break a pane of glass to release an internal spring-operated mechanism.
Primitive manual stations, requiring only a single action or hand motion to activate, can be subject to unwanted activation by jarring or accidental contact. After operation, most fire alarm pull stations must be restored to the ready position using a special tool or key in order for the panel to be reset. 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, sending an alarm to the fire alarm control panel. 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.
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