Safety thinking has radically changed since 9/11. Demand for escape chute in buildings has increased in the aftermath of the terrorist attacks in the USA on September 11, 2001. Ever since the World Trade Center towers collapsed so quickly and unexpectedly that many people had no time to escape, safety officials and engineers have been trying to think of efficient disaster escape plans to get people out of very tall buildings. An emergency escape chute is just one of the answers.
Introduction
The use of escape chute system may be new or unfamiliar in some countries, but the concept of escape chute was developed hundred years ago. Since then, with the advancement in technology and innovation, different variations of escape chute are being developed worldwide with intended performance to take people out of burning high-rise structures during life threatening emergencies. The use of escape chute is a potential means of life saving during emergency egress for those with difficulties or has no ability to use stairs.
There is no standard for the design and construction of escape chutes in meeting specific performance requirements. The lack of knowledge present extraordinary challenges for the first-time buyers -- what to assess in the strengths and weaknesses of the intended performance of the chute they plan to buy. The purpose of this article hopes to provide some basic information necessary for building safety professionals, owners and management of buildings to be aware of when source for escape chutes and its suitability of use for their building exit strategies.
Frequently Asked Questions
Currently, there are no Codes require buildings to provide escape chutes for aiding evacuation, nor Standards developing bodies that have come up with standards to address the performance of escape chutes. If current fire regulations do not require buildings to provide escape chutes to aid rescue or evacuation purposes, should it be used? Would a life saving chute need to be constructed with fire resistant materials to protect the users from the fire effects once inside the tube? Should it be designed to safeguard those who are most vulnerable in an emergency: children, the elderly, the injured, and the disabled to use the chute during evacuation? Should the chute be designed to allow the users to have the ability to self-control the speed of own descends? Should it also be designed to allow external means to control the speed of one’s descend from the outside? Should it be manufactured in conformance to its performance as “escape chute” tested by a fire research institute? How should the platform and the storage of chute be designed and installed? When a chute is installed in a fixed and permanent location whereby building occupants recognized that it is meant for emergency use only, should such egress provision be considered as an emergency exit? Finally, while high-rise occupants are accustomed to the conventional use of elevators/lifts and stairs in gaining access and egress from a tall structure, would people under life threatening situations use the unfamiliar chutes to get out alive even to the extend in risking injuries?
A study on why escape chutes are not commonly installed in buildings suggests the lack of knowledge of building safety professionals about using such systems as a means of emergency fire escape. Further, there are currently no standards for addressing the performance of escape chutes, nor mandatory requirement for placing them in structures for aiding rescue or evacuation purposes.
Alternative Means of Escape
While not recognized by Codes, escape chutes are used voluntarily at buildings and at high-hazard industrial occupancies in many countries, provide possible solutions in an effort to salvage life in extreme emergencies. In many situations, escape chute is recognized by many fire authorities as a hardware solution to correct egress deficiencies and to increase egress capacity in old buildings where it is not possible to provide fire escapes or increase the size of existing stairways in its structure.
While the idea of a chute evacuation may not be something that is very appealing to some people, it has slowly gained popularity. Given the opinion that elevators/lifts are unsafe to use for fire egress, stair travel is taxing and potentially dangerous for the aged and the disabled, evacuation via escape chutes provides the answer to make means of egress available to all people. As the escape chute can be installed at strategic locations and at heights within the structure, will operate even if the electrical supply to a building is lost during a fire, it is intended as a supplement to the existing egress, provide redundancy and back-up as an alternative escape route. The innovative applications in escape chute technologies have enabled designers and architects to have a new way of thinking in egress design to meet performance-based specifications for the provision of evacuation accessible to everyone in the built environment.
The Variations And Differences In Specifications
Escape chute varies in price and in its specifications. Some chute may have look-alike appearance in resemblance to another chute but the specifications are difference. Such as, the materials used for the construction of chute components, its descending systems, and its safety features. Chute- and slide-based devices typically use a fabric tube deployed from a location up to 30 stories above the ground and require run-out room to allow evacuees to slow before exiting.
Generally, the differences between the variations of escape chute can be classified as, (1) the compositions of the chute tube, (2) the descending systems, and (3) the chute platforms for holding and storing the escape tube. Not all escape chutes are tested by the fire research institute for its intended function.
(1) Chute Tube: Some chute tube is made of different layers of fire resistant fabrics, while other is from fire retardant fabrics. Some chute tube is made of large steel coil with fire retardant materials, while other is of heavy-duty nylon tubular net.
(2) Descending Systems: There are vertical gravity descends type, spiral descends type, and sloping-sliding descends type. Most systems are of free fall type with no or little possibilities of self-controlling descend speed or aids to control speed of one’s descend. Some chute has a series of stainless steel coiled springs sewn into the material, intend to restrict the speed of descend. Another system that uses braking coat spuncell in allowing users to self-control his/her own speed of descend and it also allow assistance from the ground to control the user’s speed of descend.
(3) Chute Platform: All chute platforms should be designed with built-in storage container to protect the chute tube from weather and other effects when unused in storage. The mechanism of the platform should be designed to allow the chute tube to be released from its storage container within seconds from unlocking the safety lever/catch and ready for immediate use. Each platform should be custom-designed to fit each installation site. The materials used for the construction of the platform are made from aluminium, galvanized steel or, depending on climatic conditions, stainless steel. In principle, all chute platforms should be constructed and installed to specification that enable them to support people with a total weight of 1000kg regardless of the chute length.
To illustrate an example, let us examines the specifications of INGSTROM Escape Chute which is manufactured in conformance to its performance as “escape chute” tested by a ‘fire research institute for fire protection’ that permit evacuation from high-rise structures during an emergency. This unique chute has a 3-separate layer of specialized materials in its construction of the fire resistant chute tube:
Inner Layer: The inner layer is made up of two materials, Twaron is applied along the length of the chute, and Flexible Rohvyl yarn based on PVC chlorofibre is used across the chute. This hybrid fabric is extremely strong, very flexible and is also of heat resistant. The inner layer bears the load of the total chute, able to withstand approximately 10,000 kilos or a maximum load of 5,600 kilos per metre width of fabric.
Middle Layer: The centered layer is made up of a very elastic 'spun cell' - made of Lycra and Modlacrylic fibres - and can easily increase three times in size. It is this layer, comparable to an elastic knee supporter, which 'hold' the evacuee as soon as the arms and legs is pressed against the chute.
Outer Layer: The outer layer of the chute, made of flexible glass fibre, provides protection against fire, heat, and smoke, and can resist temperatures of up to 800°C. When firemen spray the chute with water, it can even be used at higher temperatures than that.
Because of the specialized materials used in the construction of the chute tube for its unique application, this particular escape chute and its built-in safety features does not come cheap in comparison to the other variations of escape chutes that are available in the market. When the chutes are regularly used for drills, this means they have to be retrieved, folded out and up a lot after each use. The materials used for the construction of this unique chute are excellently suited for that purpose. The chute bears some resemblance to a giant nylon stocking - just many times longer. It may have a length up to 150 metres, is incredibly strong and also withstand heat of up to 800°C. The evacuees sit on the rim of the escape chute and lower themselves slowly down. Around the evacuee a kind of cocoon is formed, much like a football in a nylon stocking. By pressing the legs tightly against the lining of the chute it becomes possible to stand up straight. As soon as the evacuee is standing up and slowly relaxes both legs, he or she will slide down through the chute. It is not necessary to go down at an awkward pace, because speed of descend can easily be reduced by pressing the arms and legs against the side of the chute. This way, capable of evacuating 30 people a minute, mass evacuations can be realized fast and safely.
Applications of Escape Chute
Escape chute is mostly customized for a specific application, for instance, in tall buildings, ferries, grain silos, air traffic control towers, or giant shovels used in the mining industry. Some installation site may require minor alterations to the fabrics of the structure to accommodate the custom-designed platform for the chute installation. Most chute installations are permanently fixed in one location served as emergency exits.
As buildings vary so significantly in terms of height, size, structure, age, fire protection, occupancy load and how they are used, each installation site for escape chute need to be surveyed, tailoring the solution to each building needs and evacuation strategy. Escape chute should not be sold as “off-the-peg” unless the buyer know where the precise strategic location for the chute to be install in the building.
There are various types of escape chute. Some are stored away in containers, such as the single-entry type mounted on the rooftop, balcony of corridor, and window, allows occupants gain access to the chute on that floor. The multi-entry type allows occupants gain access to the chute at each floor where several levels can be simultaneously evacuated. In addition, there is a mobile version, which can be attached to a sky lift or ladder truck.
Main Common Mistakes Organisations Make
Price is an important factor but buyers sometimes over-emphasise it, to the point that they ignore the manufacturer and the supplier background and whether they offer good product with installation and after-sales services.
Another shortcoming is a lack of knowledge on what product is suitable for their buildings and their proper installation. With so many variations of escape chute that are available in the market, the buyers should assess and compare the specifications, the strengths and weaknesses of the intended performance for each system/option and its suitability of use for their building exit strategies.
Key Considerations - Specifications And Performance
When customers select and adopt an escape chute system, they have to evaluate the products. For instance, are these products reliable and are they any references in the past that used these products? If the manufacturer and supplier have a good track record, they can offer the right product, the right installation and good services to the customers. Following are some of the key factors that would need to be consider in making a sound investment decision of the RIGHT escape chute:
Quality of Materials – fire resistant materials that protect users from flame, heat, and smoke.
Safety Features -- maximum life safety protection – minimum risk of injuries -- assurance of all evacuees can get down to the ground relatively safe in seconds and within minutes.
User-friendly -- easy to use by everyone -- able-bodied, disabled people, elderly, young, woman and injured people on stretcher -- without assistance or with minimum assistance -- even without prior practice during emergency.
Operating Systems – quick to deploy and always ready for immediate use – even in power outage.
Testing and Commissioning of chute installations, training to users.
Country of Origins, Test Certificates, and Operating Manuals.
Product Warranty and Product Liability Insurance.
After sales service – maintenance package.
Comparing cost and benefits with all available options.
When available, ask for a demo-chute where you can see and slide to feel its performance. For safety's sake no price should be too high in buying the RIGHT escape chute that permits safe evacuation approved by a fire research testing institute for fire protection.
As in all evacuation plans, first responders, building managers and even tenants would need to be trained and drilled in how to use the escape chute system safely to ensure that the last great barrier to access, egress is overcome for all! With frequent practice in drills, evacuee will even feel safer descending down the long chute than negotiating the long flight of stairs during mass evacuation. This way, the evacuation process will be well coordinated and more people can get down rapidly. As in all fire protection equipment and elevators/lifts, the escape chute would need to be maintained periodically to ensure it to be effective in an emergency.
Conclusions
Presently, there are no codes around the world which permit the use of elevators/lifts in fire egress situation and neither were there codes require building to provide escape chute as a secondary means of emergency egress for all occupants. However, it is evident that escape chute do offer an additional means of egress in instances where an extreme event is imminent and rapid simultaneous evacuation is warranted, especially for those buildings that are not designed for full-scale evacuation. While many believed that escape chute appears to be a viable evacuation technique for various applications, the buyers should ensure the basic requirement of the escape chute that they intend to buy is, of course designed to permit safe evacuation in fire situations.
This article is contributed by Escape Consult Mobiltex (S) Pte Ltd. For more information on Ingström Escape Chute, please visit www.escapeconsult.com
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