Wellglass and bay lighting solutions are commonplace in hazardous areas. Both solutions are typically used across similar applications; warehouses, storage facilities, and others which require general illumination over large, open areas.
So, what are the differences between the two types of luminaire, and is one better than the other? This is something we’ll try answer in this article, but simply put, wellglass luminaires tend to be based on a traditional design using conventional lighting technology (such as metal-halide or high-pressure sodium), whereas bay luminaires tend to be based on a more recent design using LED technology.
The design of a wellglass (and the nature of conventional lighting technology), means they tend to emit light omnidirectionally, 360 degrees. This can result in a great deal of light being wasted, while also potentially causing issues with light pollution. Some wellglass solutions are available with reflectors to target more light towards a specific area; however, this tends to be a very inefficient, meaning more light is wasted.
In contrast, a modern LED bay can target the light exactly where needed. LEDs are a directional light source; as well as ensuring less light is wasted, this also helps to overcome issues with light pollution. By using different optics on the LEDs, luminaires such as the SPARTAN High Power Bay are available with a variety of beam angle options to suit different applications and setups. The use of optics is a much more efficient method of directing the light to its target area.
Ease of Maintenance
A wellglass tends to be certified using the Ex d ‘flameproof’ protection method, meaning the luminaire is designed using flame-paths. To access internal components, several bolts (which are required to maintain a suitable flame gap) must be removed and replaced when carrying out maintenance procedures, or routinely changing the lamp. Generally, this will take place on an annual basis, although it could be required more frequently in areas of high vibration which will reduce lamp life. This makes ongoing maintenance complicated and time consuming.
In contrast, a more modern LED bay tends to Ex e certified. This means there is no requirement for flame-paths, and they can be much easier to maintain. For more information on Ex e versus Ex d certification, read out comparison article here.
Frequency of Maintenance
Not only is a wellglass more difficult to maintain, it’s also more vulnerable to damage.
A wellglass is designed with a large protruding glass dome, meaning the luminaire is more vulnerable to breakage in applications where there is a risk of impact. Although wellglass solutions are available with a protective cage (to shield the glass from impact), in many cases this could be insufficient to protect it from damage. Replacement glass is likely to be expensive, as it generally is encapsulated into a machined casting which includes the flamepath, and has to be purchased as a complete assembly. While a bay luminaire also uses a glass front, the glass tends to be flat, stronger and less vulnerable to impact breakage.
Furthermore, the components used in a traditional wellglass, such as the capacitors, ignitors and ballasts, are also prone to failure as a result of being exposed to increased temperatures (conventional technology such as high-pressure sodium or metal-halide can generate significant heat compared to more modern LED alternatives). As well as an LED bay being much cooler running, it also relies on fewer components, reducing the risk of failure and allowing it to run much more efficiently.
In summary, LED bay luminaires represent a step forward in design and performance compared to more traditional wellglass fittings. While we have touched on some of the benefits of LEDs over conventional lighting, in reality there are also many more advantages (longer lifetime, improved colour rendering, the ability to instantly restrike, dimming etc.). While some manufacturers now offer wellglass luminaires with LEDs fitted inside, these solutions still carry the limitations associated with the overall design and housing, and as such, are unlikely to offer the same benefits as a bay luminaire which has been designed specifically around the LEDs.