Contrary to popular belief, escape chutes used as a means of emergency evacuation by entrapped persons from high areas is not a recent innovation
The first recorded article about a fabric-based escape chute is dated in the 1860s, when two Frenchmen demonstrated the use of two fabric cylinders to slide down from a balcony in Austria. In 1976 a Gerald Zephine of France then developed and patented the three-layered vertical escape chute, which is the basis of all vertical escape chutes produced today.
Since then an inclined escape chute and a spiral chute have been developed by Masaya Uyeda of Japan in the early 1980s. Today, in both Japan and Korea, some 100,000 inclined chutes have been installed.
Fabric chute construction
What is a vertical escape chute? It is three fabric tubes fitted one inside the other, each with its own purpose. The outer chute can withstand a constant radiated heat of 600˚C but will start to deteriorate at 800˚C. The middle chute is there to assist in the descent speed of the chute user, and is constructed using cotton and elastomer. It has a relaxed diameter of 28cm but can expand to 60cm, so the chute can apply internal pressure to the chute wall and thereby regulate descent speed.
The inner chute is there to take the weight of the chute user. For example, in a 20-storey building of say 60 metres in height, the chute will carry a weight of approximately 1,875kgs.
Escape chute use
The descent speed of a trained user will be around four metres per second; a first-time user, however, will descend at around two metres per second.
Chute users will of course vary in size, ability and condition. Should a potential user be injured or incapacitated in some way, another chute user could enter the chute and come to a stop. The injured person could then be passed to the user in the chute, who can help guide them down. It is also possible to strap a casualty to a polyethene sled and again guide them down with another user.
Babies and children under six should be carried by an adult, but older children can use the chute on their own.
Elderly persons with limited strength and movement should also travel with a fit adult. In the case of elderly care homes and hospitals, it is recommended that only inclined chutes be used.
Vertical escape chutes can be used in either single- or multi-entry ways. The former is when an escape chute is deployed from any structure, and drops to ground level, with evacuees entering at the top and exiting at the bottom.
The installation point will be selected for ease of access, ensuring that there are no obstacles (e.g. trees, phone and power lines, protruding air conditioners, other balconies, fencing and parked vehicles) in the way of the free-falling chute.
The design of the escape chute storage/deployment container will be dependent on the building’s configuration, but whatever it is the steel chute container system must fit it.
Consideration must also be given to the quality of the building construction, and the fixing of the chute container systems to the structure. The chute system will deploy a chute with a centre line of at least 120cm from the building’s wall, allowing an ideal gap between the chute and the wall of a minimum of 90-120cm. The further out and the higher the installation, the stronger the steel structure must be to support the weight of the users.
Multi-entry is where a series of chutes (there is no limit to how many are placed in position) allow numerous evacuees to use that chute. They would not have to make their way to where the chute is installed, but simply walk up to the chute, grab the chute coming down from the floor above, and enter. As with a single-entry chute there is only one exit point. For the multi-entry chute to work in a building or structure there must be the same allocated space and position allowed for each floor.
A chute room/cubicle is constructed on each floor with a minimum size of around 1×2.4 metres and made of fire-resistant materials (rated at RF120 to fire). The fire door must also be fire-resistant for 120 minutes. It is recommended that emergency battery-powered lighting be installed in the room.
A multi-entry system can be positioned outside the building by the construction of a steel tube running from ground level to the top of the building, with an entry point cut into the building’s outside wall.
The average evacuation rate of a single vertical escape chute is between 26 people per minute.
Summary
Why escape chutes are not commonly installed in buildings would suggest a lack of knowledge by building safety professionals regarding such systems as a means of emergency egress. Adding to the fact that there are no standards for addressing the performance of escape chutes, nor any mandatory requirement for placing them in structures for aiding rescue or evacuation purposes, we remain with the approved stairwell evacuation while various recent disasters indicate that we ought to at least give the potential evacuees an alternative means and, therefore, a chance to escape.
