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The Osram HSD is equivalent to Philips MSD and Sylvania BriteArc /D lamps.  It is a long life version of the more common HMI, Philips MSR and Sylvania BA250/2 lamp.  The arc length is increased somewhat and the arc tube loading is reduced, so as to extend the life.  They were developed for use in small low-cost moving heads used in restaurants, cafes etc to satisfy part of the market that was not really so interested in precision optical control, and where burning hours were longer and therefore a longer life lamp was helpful to reduce operating costs.  Due to the quite low performance, these long life lamps did not become popular in professional applications.

Well, here we have three 150W quartz MH lamps in 'Venture' style. All three burners are essentially the same. The one on the top just lacks zirconia white coating because it is a color lamp. The one on the bottom has some unfused quartz tubes at the ends, but this does not mean much, just some minor technological nuances.

Also you can see, pinch styles on the external bulb are essentially the same too - just obviously, G12 lamp runs two foils leads.

Regarding visually identical, but technologically different burners in use - just anyone related to the mass production, myself including, can confirm that unnecessary nomenclature is avoided like plague! Even slightly higher costs are usually tolerated in the name of parts unification.

Pity I missed this. Let me know if you plan on selling any more, boiler1011.

I know Sylvania made F32T8 dimming ballasts that could work with standard incandescent dimmers, as well as 0-10V controls.

Overheating of components the lamp and/or lanterns are not designed for:
Socket (the one on the top) not rated for the temperature it may reach when Rx7s burned vertically
Seal construction, designed to never be on the top, the one on the bottom running too cold and suffer from liquid fill exposure it may not be designed to handle.

The fact the burners look similar and even could be made using the same components does not necessary mean they are the same. There may be differences in the fill sand used to fill the space around the lead wires in the seal tubes (assume CMH here), there even may be differences in exact dimensions of those arctube parts, optimizing the performance when the use won't expose them to the aggressive (towards the PCA material) fill salt condensate so won't need to resist that condition.

I’d say tradition?, you wouldn’t assume Rx7 to be run vertically but to the discharge tube it probably wouldn’t make any difference as the zinc oxide white end coating is applied anyway?
Interestingly though, all the lamp catalogues and guides I’ve read over the years state slightly higher lumen output and better performance when running vertically?

Always wanted to know, but was too afraid to ask

Assume we have two MH lamps, one is Rx7s, other is G12 type. Both have the same symmetrical burner, the same tube diameter. But Rx7s one is listed for horizontal +- 45 degrees burning position, and G12 is listed as universal 180. Any physical reason behind this? Or is it just a 'tradition'? )

Come here and get a 

 

Had first proper lesson on the bass today, didn't do too bad, plenty of practising for next week, though 

Keep it up! I've heard Mark King needs an assistant.