Published at Thursday, September 29th, 2016 - 02:18:13 AM. Door. By john.
Types of mechanism Door : Hinged doors Most doors are hinged along one side to allow the door to pivot away from the doorway in one direction, but not the other. The axis of rotation is usually vertical. In some cases, such as hinged garage doors, the axis may be horizontal, above the door opening. Doors can be hinged so that the axis of rotation is not in the plane of the door to reduce the space required on the side to which the door opens. This requires a mechanism so that the axis of rotation is on the side other than that in which the door opens. This is sometimes the case in trains or airplanes, such as for the door to the toilet, which opens inward. Most doors are hinged along one side to allow the door to pivot away from the doorway in one direction, but not the other. The axis of rotation is usually vertical. In some cases, such as hinged garage doors, the axis may be horizontal, above the door opening. Doors can be hinged so that the axis of rotation is not in the plane of the door to reduce the space required on the side to which the door opens. This requires a mechanism so that the axis of rotation is on the side other than that in which the door opens. This is sometimes the case in trains or airplanes, such as for the door to the toilet, which opens inward. Rotating doors A revolving door has several wings or leaves, generally four, radiating from a central shaft, forming compartments that rotate about a vertical axis. A revolving door allows people to pass in both directions without colliding, and forms an airlock maintaining a seal between inside and out. A pivot door, instead of hinges, is supported on a bearing some distance away from the edge, so that there is more or less of a gap on the pivot side as well as the opening side. In some cases the pivot is central, creating two equal openings. High-speed door A high-speed door is a very fast door some with opening speeds of up to 4 m/s, mainly used in the industrial sector where the speed of a door has an effect on production logistics, temperature and pressure control. high-speed clean room doors are used in pharmaceutical industries for the special curtain and stainless steel frames. They guarantee the tightness of all accesses. The powerful high-speed doors have a smooth surface structure and no protruding edges. Therefore, they can be easily cleaned and depositing of particles is largely excluded. High-speed doors are made to handle a high number of openings, generally more than 200,000 a year. They need to be built with heavy-duty parts and counterbalance systems for speed enhancement and emergency opening function. The door curtain was originally made of PVC, but was later also developed in aluminium and acrylic glass sections. High Speed refrigeration and cold room doors with excellent insulation values was also introduced with the Green and Energy saving requirements. In North America, the Door and Access Systems Manufacturing Association (DASMA) defines high-performance doors as non-residential, powered doors, characterized by rolling, folding, sliding or swinging action, that are either high-cycle (minimum 100 cycles/day) or high-speed (minimum 20 inches(508 mm)/second), and two out of three of the following: made-to-order for exact size and custom features, designed to be able to withstand equipment impact (break-away if accidentally hit by vehicle) or designed to sustain heavy usage with minimal maintenance. Automatic Door Automatically opening doors are powered open and closed either by electricity, spring, or both. There are several methods by which an automatically opening door is activated: A sensor detects traffic is approaching. Sensors for automatic doors are generally: A pressure sensor – e.g., a floor mat which reacts to the pressure of someone standing on it. An infrared curtain or beam which shines invisible light onto sensors; if someone or something blocks the beam the door is triggered open. A motion sensor which uses low-power microwave radar for the same effect. A remote sensor (e.g. based on infrared or radio waves) can be triggered by a portable remote control, or is installed inside a vehicle. These are popular for garage doors. A switch is operated manually, perhaps after security checks. This can be a push button switch or a swipe card. The act of pushing or pulling the door triggers the open and close cycle. These are also known as power-assisted doors. In addition to activation sensors automatically opening doors are generally fitted with safety sensors. These are usually an infrared curtain or beam, but can be a pressure mat fitted on the swing side of the door. The purpose of the safety sensor is to prevent the door from colliding with an object in its path by stopping or slowing its motion.A mechanism is set in modern automatic doors to ensure that door will be in open state in case of power failure. Others Up-and-over or overhead doors are often used in garages. Instead of hinges it has a mechanism, often counterbalanced or sprung, that allows it to be lifted so that it rests horizontally above the opening. A roller shutter or sectional overhead door is one variant of this type. A tambour door or roller door is an up-and-over door made of narrow horizontal slats and rolls up and down by sliding along vertical tracks and is typically found in entertainment centres and cabinets. Inward opening doors are doors that can only be opened (or forced open) from outside a building. Such doors pose a substantial fire risk to occupants of occupied buildings when they are locked. As such doors can only be forced open from the outside, building occupants would be prevented from escaping. In commercial and retail situations manufacturers have included in the design a mechanism that allows an inward opening door to be pushed open outwards in the event of an emergency (which is often a regulatory requirement). This is known as a breakaway feature. Pushing the door outward at its closed position, through a switch mechanism, disconnects power to the latch and allows the door to swing outward. Upon returning the door to the closed position, power is restored. Rebated doors, a term chiefly used in Britain, are double doors having a lip or overlap (i.e. a Rabbet) on the vertical edge(s) where they meet. Fire-rating can be achieved with an applied edge-guard or astragal molding on the meeting stile, in accordance with the American Fire door. Evolution Door is a trackless door that moves in the same closure level as a sliding door. The system is an invention of the Austrian artist Klemens Torggler. It is a further development of the Drehplattentür [de] that normally consists of two rotatable, connected panels which move to each other when opening.
Related accidents Doors : Door safety relates to prevention of door-related accidents. Such accidents take place in various forms, and in a number of locations; ranging from car doors to garage doors. Accidents vary in severity and frequency. According to the National Safety Council in the United States, 300,000 injuries are caused by doors every year. The types of accidents vary from relatively minor cases where doors cause damage to other objects, such as walls, to serious cases resulting in human injury, particularly to fingers, hands, and feet. A closing door can exert up to 40 tons per square inch of pressure between the hinges. Because of the number of accidents taking place, there has been a surge in the number of lawsuits. Thus organisations may be at risk when car doors or doors within buildings are unprotected. According to the US General Services Administration: ...It is essential that childrens fingers be protected from being crushed or otherwise injured in the hinge space of a swinging door or gate. There are simple devices available to attach to the hinge side, ensuring that this type of injury does not occur. As the door closes, the hand is pushed out of the opening, away from harm. In addition, young children are vulnerable to injury when they fall against the other (hinged) side of doors and gates, striking projected hinges. Piano hinges are not recommended to alleviate this problem as they tend to sag over time with heavy use. Instead, an inexpensive device fitting over hinges is available on the market and should be used to ensure safety... Outward and inward opening Whenever a door is opened outwards there is a risk that it could strike another person. In many cases this can be avoided by architectural design which favors doors which open inwards into rooms (from the perspective of a common area such as a corridor, the door opens outwards). In cases where this is infeasible, it may be possible to avoid an accident by placing windows in the door. However, inward-hinged doors can also escalate an accident by preventing people from escaping the building: people inside the building may press against the doors, and thus prevent the doors from opening. This was partly the case in the Grue Church fire in Norway in 1822. Today, the exterior doors of most large (especially public) buildings open outward, while interior doors such as doors to individual rooms, offices, suites, etc. open inward, as do many exterior doors of houses, particularly in North America. Doorstops Doorstops are simple devices used to prevent a door from coming into contact with another object (typically a wall). Without the door stop damage might be done to the wall. They may either absorb the force of a moving door, or hold the door in place to prevent unintended motion. Door guards The purpose of door guards (also known as hinge guards, anti-finger trapping devices, or finger guards) is to reduce the number of finger trapping accidents in doors, as doors pose a risk to children especially when closing. Door guards protect fingers in door hinges by covering the gap that is created by opening doors by covering the hinges of doors with a piece of rubber or plastic that wraps from the door frame to the door. There are also door safety products which eject the fingers from the push side of the door as it is being closed. There are various levels of door protection. Front door protection a front anti-finger trapping device but leaves the rear hinge pin side of the door unprotected. Full door protection uses front and rear anti-finger trapping devices and ensures the hinge side of a door is fully protected. Which level of protection is appropriate should be determined by a risk assessment of the door. There is also handle-side door protection, which prevents the door from slamming shut on the frame, which can cause injury to fingers/hands. Safety doors A safety door prevents finger injuries near the hinges without the use of door guards. Rather than cover the danger area, the approach is to change the shape of the door so that an accessible gap does not form in the first place. This is achieved by adding a perfectly circular ("bull-nose" shaped) extension to the door, which moves in and out of a cavity as the door opens and closes. This prevents any part of a hand being crushed near the hinges – either inside or outside. These doors have an operating range of slightly over 90 degrees, so their use is limited to where they come into contact with a side wall when fully open (or where they can be prevented from opening too far by a doorstop). Glass doors Glass doors pose the risk of unintentional collision if a person believes the door to be open when it is closed, or is unaware there is a door at all. This risk may be particularly pronounced with sliding glass doors because they often have large single panes which are hard to see. To prevent injury from glass doors, stickers or other types of warnings are sometimes placed on the glass surface to make it more visible. For instance, in the UK, Regulation 14 of the Workplace (Health and Safety Regulations) 1992 requires the marking of windows and glass doors to make them conspicuous. Australian Standards: AS1288 and AS2208 require glass doors to be made from laminated or toughened glass. Fire Special purpose fire doors are often employed in buildings to reduce the overall risk of fire, particularly by preventing the spread of fire and smoke. In cases where they are improperly installed, employed, or tampered with, the risk of fire can be increased. Door closers are sometimes used to ensure fire doors remain closed. An additional risk in a fire is that doors may prevent access to emergency services personnel in order to fight the fire, rescue occupants, etc. Door breaching techniques may be required in these situations to gain access. Panic bars are often used in buildings so that a door locked from the exterior can quickly and easily be opened from the inside in the event of a fire or other emergency. Vehicle doors There may be an increased risk of trapping hands or fingers in car doors compared to other types of doors, due to the proximity in which the occupant sits. In some car accidents, injury to occupants from the movement of car doors may occur Bicyclists often fear collision with an opening car door in case the cars occupant does not look carefully to check that it is safe to open the door. Because cyclists often ride near parked cars along the side of the road (see door zone) they are particularly vulnerable. Aircraft doors Doors which lead from interior, pressurized, sections of an aircraft to exterior or unpressurized areas can pose extreme risk if they are inadvertently opened during flight. This can be mitigated by having doors that open inwardly and are designed to be forced into their door frames by the internal cabin pressure – most cabin doors are of this type. However, an outward opening door is often advantageous for cargo doors to maximise available space, and these need to be secured by hefty locking mechanisms to overcome internal pressure. A number of accidents have occurred where outward-opening aircraft doors were opened in flight, often accidentally: • American Airlines Flight 96 (1972) • Turkish Airlines Flight 981 (1974) • United Airlines Flight 811 (1989).
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