Maintaining Ex Lighting: Modular vs Sealed for Life – Part 1
Part 1 – What’s the Difference?
In this 4-part series, we compare ‘modular’ and ‘sealed for life’ LED Ex luminaires, and how the design and certification of these different approaches impacts how easily maintenance can be carried out. In this first instalment, we’ll look at what we actually mean by ‘modular’ and ‘sealed for life’ and identify the key differences in how these solutions have been designed.
Maintenance is an important consideration for lighting in hazardous areas. It is required to ensure the luminaires are compliant and are operating at their optimum. However, carrying out the maintenance can be challenging and costly (both from a monetary and environmental perspective). Choosing an LED solution will help to ensure maintenance is kept to a minimum, but the challenging nature of hazardous area applications means routine maintenance checks are essential, while as with any electrical product, unplanned maintenance is still a possibility. Ensuring maintenance of the luminaire can be carried out as quickly and as easily as possible is therefore an important consideration. But, how do you know whether a luminaire is easy to maintain or not? Simply put, Ex luminaires can be categorised in two ways;
Sealed for Life Luminaires – Many Ex lighting solutions are factory sealed (or encapsulated), primarily as a method of protection (as part of the luminaires hazardous area certification). Once sealed, the luminaire cannot be opened up and internal components cannot be accessed, i.e. ‘sealed for life’. From a certification perspective, this design is generally perceived as being a more straightforward method of achieving Ex approval but does have its limitations. Because the factory seal is such a critical part the luminaires hazardous area rating, it cannot be opened without invalidating the certification. Doing so would render the unit unsuitable for use in hazardous areas and could present an explosion risk. As a result, maintenance of a sealed for life luminaires is very limited.
Modular Luminaires – In contrast, ‘modular’ luminaires are specifically designed in a way which allows them to be opened up and accessed for maintenance, without invalidating certification. This is mainly because the luminaire does not rely on being factory sealed to achieve its hazardous area rating. While encapsulation may still form a part of the certification, this is likely to be at a component level (such as encapsulated drivers), rather than the entire luminaire. Without this restriction, maintenance becomes much easier and components can be changed or inspected without invalidating the luminaire’s certification.
Now we’ve established how the design and certification of Ex luminaires can be different, and how it impacts the ease of maintenance, the next question is, ‘why is maintenance so important?’
In Part 2, we’ll look at downtime during maintenance, and how the design of these two solutions will affect the length of time a user is likely to be left without light during a common maintenance procedure.