[PerryinCA]

Well, there have been a few different thoughts circulating the internet community, and its become apparent that even many of the Manufacturers which have stateside reps are unsure what its exact meaning is, so I went over to the source, the engineers and this is what I found. The following is a cut and past from a RC thread I posted it on.

....Lets settle this HQI thing once and for all. HQI, in the lighting industry, refers to High Quartz Iodide,metal halide bulbs. whether they be double ended(most common), fibre optic reflector, or single ended halides. People have thought differently on the topic, and there has been a widespread confusion (which I myself have been guilty of assisting). All HID lamps have an inner arc tube contained within an outer galss sleeve, borosilicate in mogul lamps (most at least) and quartz in the double ended lamps. The mogul/medium lamps offer better (although in many cases still not enough as per some of the experts opinions) UV protection. (that can be debated)

The arc tube consists of a starting electrode, a main electrode, a starting gas, and arc metal. Mercury vapor HID lamps contain an all quartz arc tube filled with mercury arc metal and argon as a starting gas. Newer metal halide lamps lamps contain less mercury and are even more efficient than mercury vapor lamps. Halogen quartz, or Quartz Iodide bulbs have a tungsten filament in a nitrogen-argon gaseous medium to which bromine has been added (halogenated!), enclosed in an envelope generally made from quartz. This doesn't mean they are HQI halide bulbs. Typical halide salts are sodium iodide, scandium iodide, thallium iodide, and indium iodide. When the iodides vaporize in the arc they form different colored layers around the mercury arc.

So, HQI is NOT limited to just DE lamps. What does the socket have to do with the gaseous composition of the lamp? Nothing really. Its becoming more common knowledge but it needs to be recognized by all, especially those looking to DIY. The subject is even more touch and vague when speaking of 400w, as there is no ANSI make for that wattage HQI. There are ballasts that will operate the lamp, but some will run better than others. In any case, an ignitor (typical of pulse start ballasts) is required.

Hope this is some help, and feel free to add, or ask any questions!

-Perry

[scubadude]

Interesting stuff!

Would it be safe to say that the DE bulbs are more effecient than the SE bulbs, provided the proper ballast of course

[PerryinCA]

I wouldn't make any distinction based on the socket type. Ballast does make a huge difference though. I have seen an average of about 15% difference between the M135, and the S51 ballasts for 400w MH, in the S51 favor.

-Perry