The Lamp Room

I'm looking for 400W lamps for highbays (vertical cap up burning position) from the quite limited selection of lamps my local wholesaler stocks

One of the options they have are Philips HPI-T (not Plus), latest generation (clear arc tube, made in China) 400W/640. Those are rated for horizontal burning position only

For what i know typically MH's are more iffy in horizontal burning positions and ok with vertical. Where the limitation with the HPI-T comes from ?

I spoke to Venture technical about this, a few years back. My understanding from their technical department, is that only elliptical lamps should be run cap up, tubular lamps should only ever be run in a horizontal alignment. I was told this is due to heat dissipation issues.

Wouldn’t bother with HPI anymore, out of the 13 Belgian ones I re-lamped in Aqua last April, 4 are now out!

the philips hpi plus elliptical lamps are suitable for bu burning. best to look on ebay for some belgium made ones that are a few years old hpi plus 400/745/bu/e40

forgot to say some of the 250w tubular ventures are marked for universal burning, i am not sure if this is the case. there is also the 360w cdm-e/t lamps made by philips that were introduced to replace hpi (ceramic metal halide)