Jeremy Lester of Switchtec explains the role of light towers as visual indicators in a wide range of industrial activities. The need to communicate in the workplace exists just the same as it does in many aspects of our life, and a prominently fitted light tower is a powerful communication tool. Its purpose is to tell those within its ‘theatre of operation’ that something has happened, is happening or is about to happen.
In practical terms, the light tower is a stack of different coloured lamps that can be illuminated or made to flash in a sequence or pattern to convey information or a warning, but why is it so important to have light towers in the workplace?
The answer is simple yet complicated – the changing face of the workplace. In the days when production processes were labour intensive, each operator worked on a single machine, which may or may not have had its own indicators and instruments fitted to it.
As the operator was working only on that machine, at any point in time he would be aware of its status both in terms of process and safety aspects. It is perhaps no exaggeration to say that in the case of the latter, the operator would probably only become aware of a dangerous situation when he fell foul of it – such was the lack of monitoring and indication.
In these days of automation, the emphasis has shifted towards fewer people controlling more machines. Clearly, in such a scenario, the operator is not able to monitor every machine all of the time. So how does he know what is happening to each machine as he goes about his work? Enter the light tower.
With a light tower fitted to each machine, the operator can now easily see when it needs attention. So instead of sitting ‘idle’ waiting for a process to finish on just one machine, he can easily work on a number of machines in sequence, whilst always being aware of an individual machine’s status.
As mentioned earlier, a light tower can be equipped to provide an audible signal or alarm. Yet its biggest strength is its ability to communicate silently. As part of the whole safety at work ethic, and to create a more friendly working environment, noise has to be kept to a minimum.
Specifically though, what information can a light tower convey? Modern light towers are able to provide a wide variety of coloured modules. Add that to the possibility to fit up to ten modules on one bracket, and the code options are massive. For example, used as a silent paging system, each colour combination could represent a different person.
Similarly, when used on a machine, each colour or combination could represent a different stage in a process or the need to execute a manual procedure such as replenish raw materials feeding the machine.
For general use, the accepted codes for single colours are as follows: Red – serious danger, act now; Amber or yellow – warning proceed with care; Green – safe condition, go ahead; Blue – specific meaning given depending on situation; Clear – no specific meaning
As touched on earlier, the tower can also be used to indicate a safety warning, perhaps to vacate a room due to the escape of noxious gases. Though for most safety warnings, this visible signal would be accompanied by an audible alarm on the basis that by attacking two senses the message transmission time is reduced.
Another variation is the flashing lamp and, a stage further still, the rotating lamp. All of these have their part to play in the quest for accurate and clear message or warning indication.
It is important to purchase the correct light tower from a number of standpoints. Firstly, it has to be capable of meeting its requirement as an indicator or warning device That is to say, where applicable it has to offer six different colours, be capable of being stacked up to five units high and for two of these to be fitted to a single bracket to provide a ten lamp system.
It should also provide the option to install an audible alarm unit and the ability to fit a choice of light types; continuous, blinking and xenon. Different light sources should be available – filament bulb, xenon tube, or for long life and durability, LED ‘bulbs’ or better still, integrated LEDs. The latter being particularly good for applications where the light tower is installed on a machine that is subject to vibration.
Look for a practical design that is easy to install with a choice of mounting brackets converting vertical or wall mounting and with extensions to raise the tower to a prominent position.
It is important that the system is made from high quality materials that will combat the effects of the local environment and uses ‘O’ rings to offer maximum resistance against the ingress of atmospheric agents. For maximum protection (hence longevity and reliability) look for a unit that offers a degree of protection to IP65. Many units available do not offer this degree of protection and will be unsuitable for applications such as outdoor use.
Looking at the construction in more detail, it is important that the light tower is truly modular and is easy to take apart, to change bulbs or modify/ add further colours, flashers, audible alarms and so on. In terms of safety, the unit should offer complete isolation from contact with live terminals and require no tools to change a bulb – it should not be possible to insert fingers or tools into any part that is electrically powered.
Such a light tower helps reduce down-time and reduces operating costs by removing the need to call in trained electricians or maintenance people simply to change a bulb. The ability to fit a rotating beacon is often important, and this should be capable of accepting standard filament bulbs for extra brightness. An audible alarm should be fully controllable to provide fast or slow pulse, high or low output and also offer tone selection.