Which Lamp Types Belong to the HID-Family?

Historically, Mercury Vapour Lamps have been the first high pressure discharge lamps.

Although they produced significantly more light than incandescent lamps thanks to fluorescent materials, they did not have good light quality. Today they have been virtually phased out due to EU guidelines.

But they have been further developed: The internal pressure of the burner was further increased and additives – metal halides – were included in the gas filling for the arc; fluorescent material was no longer necessary. The metal halide lamp was born. It is still a very efficient and flexible light source today. The metal halide lamp product family is large and can be used in a variety of ways in general lighting, but is also suitable for applications in the field of special lamps.

Sodium as a filling element ensures the particularly efficient yellow radiation components. Sodium vapor lamps are easy to recognize due to their tubular ceramic burner. Street lighting is still hard to imagine without the yellow light today – and also provides insect protection.

What is Special for Metal Halide Lamps?

Metal halide lamps are very bright: they produce a lot of light from comparatively small burners. So, because the shorter the arc, the better the light can be directed by reflectors.

Due to the broad emission spectrum, the light quality is very close to natural sunlight – depending on the filling composition – also due to the high UV content. The UV radiation can be greatly reduced or completely eliminated by suitable filters in the glass of the lamp bulb or in the front panel of the luminaire.

Why is Mercury needed in Metal Halide Lamps and how long will it still be allowed?

A small amount of mercury is required in the lamp filling for clean ignition, high efficiency and the blue part of the radiation spectrum; other elements complement other colors in the plasma and thus determine the light quality (color rendering).

For the essential use of mercury, there is currently an 'exemption approval' through the EU RoHS Directive (Restriction of Hazardous Substances; HID exception according to Annex X 4e). The provisions/ exceptions of this directive are revised every 5 years; the current edition is valid until 2027 – with the option of a further extension.

Which Brand Names and Application Areas are Known for Metal Halide Lamps?

In the professional community, this type of lamp is known under brand names such as HQI, Powerstar, Nachroma FLUX or LOX, Staturion, Topflood – and the blue ones for aquaristics are also known as 20k lamps. For Radium, the type designation is HRI.

Many of these high-quality light sources are built in the Radium factory in Wipperfürth, so they are 'Made in Germany'. And we know what we're doing: the first lighting with 3500 W metal halide lamps for the 1972 Olympics in Munich came from Wipperfürth. Others followed, such as the lighting for the 2014 World Cup.

The so-called '2 kW/N' is legendary and has 'reinvented itself again and again' in the sense that its burners have become smaller and smaller over the years, making them more efficient. Other members of the product family and their corresponding applications are listed below.