The activation of a manual fire alarm is usually achieved through the use of tensile stations (US & Canada) or call points (Europe, Australia and Asia), which then sounds an evacuation alarm for the relevant building or area. The activation of manual fire alarms requires human intervention, which is different from automatic fire alarm activation as provided through the use of heat detectors and smoke detectors. It is, however, possible for the call point/tensile station to be used in conjunction with automatic detection as part of the fire detection and alarm system as a whole. Systems in completed buildings tend to be connected and include a control panel. Systems for use during construction can also be wireless or mechanical, but are advised by the Structural Wood Association in the UK that for timber-framed construction, interconnect wireless systems are used.
Video Manual fire alarm activation
Fire alarm pulling station
A fire alarm towing station is an active fire protection device, usually installed on the wall, which, when activated, starts an alarm on the fire alarm system. In its simplest form, the user activates the alarm by pulling the handle down, which completes the circuit and locks the handle in the enabled position, sending the alarm to the fire alarm control panel. After the operation, most fire alarm towing stations should be returned to the ready position using a special tool or key to reset the panel. The primitive manual station, requiring only one action or hand movement to activate, may be subject to unwanted activation with a jarring or accidental contact. Preliminary strategies to address this problem include requiring operators to break glass panels to release internal semicommunication mechanisms. Manual pull stations that require two hand movements, such as lifting and pulling down, or pushing and pulling down, have since replaced the glass shards and single action models in many modern installations.
The encoded pulling station
In the past, tensile stations controlled the entire system. This coded pullout station is much larger than the modern pull and has a code wheel inside it. They have a gear mechanism that ends when the station is pulled, and (unlike modern pull stations) the grip does not go down. The gears will rotate the small wheel with a certain number of teeth, which determines the encoding. His teeth will rise to the contact, which will open and close the circuit, vibrate the code into the bell or horn. This code is used by building security to determine where the alarm originated. For example, consider a pull-station in the lobby of a four-storey office building elevator code 5-3-1. When the station is withdrawn, the security guard in the building will search 5-3-1 in the master code list. After finding the location of the pull, they will check whether there is a real fire. If anything, they will evacuate the building and call the fire department.
System testing can be done in one of two ways: In a coded pulling station, there is a test hole on the front (usually activated with an Allen English key) or an inner test switch. Enabling a one-way switch causes the notification tool to sound continuous (or in the case of one-tapping bells, once ding). Changing it in another way and then activating the pull allows a quiet test to be performed in which the station's mechanical parts are checked to ensure proper functioning. Once withdrawn, the station will perform at least four code rounds before resetting itself. The code withdrawal is usually used in new fire alarm systems until about the 1950s, and sometimes until the 1970s. Until the early 1990s, some panels were created with additional zones to accommodate existing coded pull stations. Currently, coded pull stations are very rare and hardly ever seen in a working fire alarm system.
Modern pull stations
Many modern fire alarms pull station is a single action and only requires the user to lower the handle to sound an alarm. Another fire alarm towing station is a double action, and thus requires the user to perform a second task before pulling down, such as lifting or pushing the panel at the station or destroying the glass panel with a hammer attached. Perhaps the most recognizable pull station is the T-bar pull, so named because the handle is shaped like the letter "T". This style is produced by many companies, especially SimplexGrinnell.
Resetting the fire alarm towing station after operation usually requires building personnel or emergency personnel to open the station using a key, which is often a hex key or a more traditional key. Opening the station will cause the handle to return to its original position, allowing the alarm to be reset from the fire alarm control panel after the station is closed.
In some places, especially in college dormitories and schools, students turn on fire alarms as a joke or just because they want to (because of anger or curiosity). These false alarms can pose a risk to apathy amongst residents if it happens repeatedly, causing them to ignore the importance of the alarm or ignore it completely. In areas where false alarms are a recurring problem, tensile stations can be covered with a 'Stopper' plastic cover that will cause people to notice the person by sounding an alarm when tweaking or opening, creating a focus on the fire alarm. Due to this and other issues, turning on the fire alarm when no fire or other emergency is illegal in many jurisdictions.
Maps Manual fire alarm activation
Manual call point
In Europe, Australia, New Zealand, and Asia, withdrawal stations are generally not used; instead of a manual call point used , commonly referred to as MCP, call point or Fire Point in 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 is in the building. They are usually connected to a central fire alarm panel which in turn is connected to the alarm system in the building, and often to the local fire fighting dispatcher as well. The first modern MCP arrived in Europe in 1972 and was developed by KAC.
The manual call point is used to initiate the alarm signal, and operates by pressing a simple button or when the broken glass reveals the 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 find the call point easily, and there must be a visual identifier of the unit triggering the alarm, usually a mechanical flag that operates on the lock and must be manually reset, eg. with a key.
Previously, the old British standards did not allow hinged cover and resetable elements. The plastic element must have the same mold as the EN 54 glass.
MCP while
It is becoming increasingly common in the UK and Europe for wireless MCP to be used in temporary environments such as construction sites. This usually provides the same level of protection as standard fire alarm installation, but can be moved as needed in a changing environment of a building under construction without requiring the installation of a special electrical technician. They often incorporate call point functions with sounder and strobe functions for easy installation.
Such systems typically operate structures similar to standard cable fire alarm networks, where the Manual Call Point can be mixed with automatic fire detection in the form of heat detection and smoke detection (often designed specifically for dustproofing, due to the increased possibility of dust at the construction site) and can be connected to the base station monitoring unit. This unit provides visual identification of the trigger unit in any alarm, and must also be able to monitor the radio signal strength (which may change during construction) and battery life.
Because of its use for life-in-progress purposes, the radio receivers used in the system must be of Category 1 standard.
European Standard
Fire detection and alarm products placed on the market within the EU shall, in accordance with Regulation (EU) No 305/2011, in accordance with harmonious European technical standards EN 54 Fire Detection and Fire Alarm Systems .
EN 54 section 11 is part of the mandatory standard associated with the manual call point .
The European Committee for Standardization (CEN, France: Comità © à © EuropÃÆ' à © en de Normalization) is responsible for the development and maintenance of standards, as part of its authority to develop the harmonization of European standards for the movement of free goods in EU countries.
The EN 54 certification of each device must be issued annually, and for such products to be issued by the agency notified in accordance with the rigorous testing procedures outlined in the standard.
If the EN 54 certificate is more than one year old, the certificate has expired and is not a valid certificate. Manufacturers can not sell or install devices with expired certification in any EU country.
See also
- Fire security
References
External links
- The video demonstrates the encoded pull station made by Simplex.
Source of the article : Wikipedia