Manual fire alarm activation: Difference between revisions

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=== Coded pull stations ===

In the past, pull stations controlled the entire system. These coded pull stations were much bigger than modern pulls and had a code wheel in them. 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. The gears would turn a small wheel with a specific number of teeth, which determined the coding. The teeth would push up on a contact, which would open and close a circuit, pulsing the code to the bells or horns. This code was used by building security to determine where the alarm was originating from. For example, consider a pull station in the fourth-floor elevator lobby of an office building with a code of 5-3-1. When the station was pulled, the security officers in the building would look up 5-3-1 in a master list of codes. After finding the ___location of the pull, they would should
check to see if there is a real fire. If there was, they would evacuate the building and call the fire department.

[[Image:Holtzercabotpull.JPG|thumb|200px|right|Antique [[Holtzer-Cabot]] coded pull station]]

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. Turning the switch one way causes the [[Fire alarm notification appliance | notification appliances]] to sound continuous (or in the case of single-stroke bells, ding once). 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. Once pulled, the station would do at least four rounds of code before resetting itself. Coded pulls were typically used in new fire alarm systems until roughly the 1950s, and then occasionally into the 1970s. Until the early 1990s, some panels were made with an extra zone to accommodate any existing coded pull stations. Nowadays, coded pull stations are rarely seen in working fire alarm systems.

=== Modern pull stations ===

Many modern fire alarm pull stations are single -action and only require the user to pull down thea handle to sound the alarm. 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 or pushing in a panel on the station or breaking a glass panel with an attached hammer. Perhaps the most recognizable pull station is the "T-bar"-style pull station, so named because the handle is shaped like the letter "T". This style is manufactured by many companies, most notably [[SimplexGrinnell]].

[[File:Activated Fire-Lite BG-12 pull station at MBTA Chinatown station.jpg|thumb|200px|Activated Notifier NBG-12 pull station underneath a Stopper cover]]

Resetting a fire alarm pull station after it has been operated normally requires building personnel or emergency responders to open the station using a key, which often is either a [[hex key]] or a more traditional key. Opening the station causes the handle to go back to its original position, allowing the alarm to be reset from the [[fire alarm control panel]] after the station has been closed.

In some places, particularly at college dormitories and schools, students can deliberately set off the fire alarmalarms as a [[practical joke|prank]] or just because they want to (because they are angry, curious, they want to seek [[revenge]] on someone, or to postpone, skip or skipcancel ana test or [[exam]]). These [[false alarm]]s can result in [[alarm fatigue]] if they occur repeatedly, causing occupants to dismiss the importance of alarms or completely ignore them. In areas where false alarms are a recurring problem, pull stations may be covered with a clear plastic cover (sold under the "Stopper" trade name) that will cause people to notice the person by sounding an alarm when tampered with or opened, creatingattracting aattention clear focus ontowards the fire alarm. The plastic covers may also be used to help prevent accidental pulls caused by bumping a pull station or accidental pulls by small children. Some covers lack internal alarms and are just used to help prevent bumping the pull station. Because of these and other issues, intentionally setting off a fire alarm when there is no fire or other emergency is [[IllegalismCrime|illegal]] in most jurisdictions.

== Manual call points ==

In Europe, Australia, New Zealand and Asia, pull stations are generally not used; instead of, a '''manual call point''' is used, which is usually referred to as an MCP, call point, break-glass point, or Fire Point within the [[fire protection]] industry and as a "transmitter" in Japan. They are used to allow building occupants to signal that a fire or other emergency exists within the building. When activated they will raise a plastic [[flag]] out of the top to tell which alarm was activated. They are usually connected to a central [[fire alarm control panel|fire alarm panel]] which is in turn connected to an [[alarm]] system in the building, and often to a local fire brigade [[dispatcher]] as well. The first modern MCP arrived in Europe in 1972 and was developed by KAC.<ref name="KAC">{{cite web|url=http://www.kac.co.uk/final/home.htm |title=KAC Home Page |publisher=Kac.co.uk |date= |accessdate=2009-07-16}}</ref>

Manual call points are used to initiate an alarm signal and operate using a simple button press or when glass is broken revealing a button. They can form part of a manual alarm system or an automatic alarm system. There will be an indicator on the monitoring unit for visual indication to locate the call point easily, and there should be a visual identifier of the unit which triggered the alarm, typically a mechanical flag that operates on a latch and must be manually reset, e.g. by a key.