Saturday 16 March 2013

Safety on doors and gates is not an end in itself

Andy Holz is Technical Sales Manager
for ASO Safety Solutions
ASO Safety Solutions, manufacturer of tactile safety sensors, has been dealing with the question for more than 25 years, of how safety on doors and gates can be ensured. Safety is not an end in itself but a precondition to prevent severe harm to personnel and machinery.

Generally speaking, installers are now very aware of and in some cases wary of the amount of standards and guidelines that cover the safe installation of powered gates and as a result they now practice risk minimisation.

Responsible for safety on doors and gates is the standard BS EN 12453 and the implied 150 Newton (15 kg) force limitation. If the acting force exceeds 150 Newtons it is obligatory to install safety devices that can protect users from danger, injuries or worse. An installer should never rely on “it will be all right” as he will be flouting his professional responsibilities and leaving himself and/or his company liable for any consequences that follow. All parties concerned (homeowner, contractor or developer) should be aware that the better a gate is built, protected, installed and maintained, the greater the chance having done everything right.

Why is there a need for safety devices on gates?

Currently, automation seems to be the most progressive development of the whole industry sector.
  • On the one hand powered gates make sure that they open and close mainly independently. Compared with manual operation, powered gates save time, money and effort.
  • On the other hand we are giving control to a machine, so it is necessary to prevent potential danger. No one would consider doing without air bags in cars, would they? So why should we be less careful when it comes to gates?

A second very influential development is green building. This term includes lots of measures and products ranging from energy saving lamps to eco-friendly materials. It does not stop at doors and gates - faced with increasing energy costs, especially the requirements relating to industrial gate systems, sectional doors and drives are growing. The shorter and faster the opening phase of a door or gate the smaller the energy loss and the shorter the personnel engagement. That saves money. But that also creates the need to respond to the increasing acting forces with safety devices in the same way as air bags in cars have also been the logical consequence of faster vehicles.

An Exemplary Sliding Gate 
That does not mean there is no necessity to safeguard pinching and shearing points on privately managed doors and gates. Children especially, should be protected from the risks in the vicinity of automated garage doors or domestic gates. Often they are not aware of the risks or do not care because they are focused on playing.

Two years ago two children were killed by sliding gates in the UK and just a few weeks ago another 3-year old girl from the Netherlands was killed by a powered gate not complying with the standards. That alone makes it obvious that this is not an academic discussion without any relation to reality. Maybe it’s because fatalities caused by gates have not had the same significance or publicity as fatalities caused by car accidents, but the people killed by powered gates in the last few years in Europe are clearly a fact that the industry needs to be very aware of.

Besides the danger of bodily injury, which is the worst case scenario, avoidable damage to property should be kept in mind. Damage to vehicles and machinery, either privately managed or industrial, can become expensive and aggravating.

Which possibilities exist to safeguard gates?

First of all automated gates should go through an adequate risk analysis to identify possible pinching and shearing points. In some cases the torque limitation of the drive and control units can be sufficient. The control monitors the drive, which generates a higher closing force in the case of an obstruction. Once the force exceeds 150 Newtons the control board checks the torque and reverses the drive to avoid any severe danger.

Bigger gates require sensitive safety edges that are installed on the pinching and shearing points. These rubber profiles are exactly customized to the gate. Before the gate exerts a force higher than 400 Newtons the gate reverses automatically and serious injuries are prevented. The safety sensors are permanently observed by safety relays to guarantee error-free operation and to ensure, that safety devices are technically available when needed. This is a European standard that is abided by actively by most of the manufacturers.

ASO Safety Solutions offers safety contact edges for this field. Depending on the gate, the circumstances and requirements, there are diverse types of safety contact edges. In this context the over travel distance is very important. The over travel distance is defined by the distance a gate covers after a receiving a stopping signal until standstill. The so called actuating distance describes how much a safety contact edge has to be pushed in until actuation. Safety can only be provided when both parameters are exactly customized to the automated door or gate system.

Of course there are also other types of sensors which can possibly prevent accidents on doors and gates.

Additional to the safeguarding of the pinching and shearing points, optical sensors like photo cells can be used to monitor the passage area of a gate. This is a preventive measure that tries to eliminate danger from the first point of contact with the system which is mainly used to detect vehicles. Induction loops are another possibility. Infrared or radar systems observe the door or gate permanently and can therefore be characterised as preventive devices which also have to be balanced carefully with the door or gate system.

If all components are set up well, the user can be quite sure that the door or gate system complies with European standards. The users will have safe and convenient access to the house, effective access to the factory building or an energy efficient access management of the building.

For further information visit or alternatively

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