Ash
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| I have a used QMH Philips HPI-T 400W that has some blackening in the arc tube on the end far from the base, which means it was running base down
I want to run it horizontal. The lamp is just tubular without the added "baloon" in the center. I seen how some tubular MH's deform the outer glass when they run horizontal, i dont want it to happen
Is this an issue or it only happens in EOL or abnormal conditions ?
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dor123
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| Ash: I think that the Philips HPI-T operates best at a horizontal burning position (Just verify, that the tip mounted upward), as it is designed for floodlighting and not so much for industrial lighting.
Running horizontally will damage especially the american probestart MH lamps, as they have exactly the same arctubes as the MV lamps, which are operates best at vertical position.
The Osram Powerstar HQI-BT/D can be operated in all positions without problems as it have a shorter and larger arctube and it have a bulged part in the section of the arctube, to prevent the softening of this area when running horizontally.
There are also many chinese tubular MH lamps that have a factory made bulged part in the section of their arctubes.
The outerbulb of the Philips HPI-T shouldn't deform during regular use when running it horizontally.
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« Last Edit: August 13, 2011, 10:25:47 AM by dor123 »
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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Ash
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| Why is it important to ru with the tip up ?
How did Philips prevent the softening of the outer tube in this lamp without adding the "baloon" in the place where the arc tube is ?
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dor123
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| Ash: The tip might act as a cold spot, so if it is mounted upward, the temperature of the arctube will be more uniform.
The baloon is required only in QMH such as the Osram HQI-BT/D that have hard vaccum in their outer.
The outer isn't deformed on QMH that contains nitrogen (Which is at low pressure) and in the case of the Philips HPI QMH lamps nitrogen+neon as it arctube contains argon+neon penning mixture.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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James
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| Another reason for burning with the tip upwards is to achieve better colour uniformity from lamp to lamp, and faster run-up times. The photometric properties and lifetime of metal halide lamps are determined by the temperature of the molten pool of metal halide salts, and it is important that during operation this pool is located in an area of the arc tube that has good dimensional control. Since the shape of the tip can vary quite a lot from one lamp to the next, if the arc tubes are run with the tip downwards that will become the coolest spot, and the metal halide salt pool will shift to the tip. Depending on how big is the void area inside the tip, the temperature of the metal halide salts will also be different, and the resulting lamp colour and life will vary. By contrast the cylindrical portion of the arc tube is very accurately shaped, and if run tip-up that will be a hotter part of the lamp, and the salts will keep out of the tip.
Also after switch-on, it is desirable for the lamp to run up as fast as possible. In case the salts are located inside the tip area, which is cooler than the cylindrical arc tube wall, it will take longer for that region to heat up.
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Ash
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| Well i powered it up yesterday and all seems to be ok
In the run-up of the lamp i noticed 2 things happen :
When first pwoered up, it rectifies (and the ballast makes very loud zzzz) for the first 5 - 10 seconds. There is some further rectification (visible flicker) during the run-up but withut the ballast buzzing
There are sometimes 1-2 yellow "flashes" during run-up
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Medved
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Well i powered it up yesterday and all seems to be ok
In the run-up of the lamp i noticed 2 things happen :
When first pwoered up, it rectifies (and the ballast makes very loud zzzz) for the first 5 - 10 seconds. There is some further rectification (visible flicker) during the run-up but withut the ballast buzzing
The buzz for the first few seconds is the uneven electrode warmup (one is faster). Then when the warming progresses, the flicker is not real rectification, but the arc root "dancing" on the electrode. After the lamp warm up further, the root find it's stable hot-spot, so the arc burn steadily. There are sometimes 1-2 yellow "flashes" during run-up
These flashes are cloud of different fill components (each of them evaporate at different temperature, so different warmup stage) passing trough the arc body. After a while, when no more fill evaporate, the gas mix up, so the arc then burn in stable atmosphere. |
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No more selfballasted c***
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dor123
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| The yellow flashes caused by the sodium when it is evaporate in MH lamps that contains sodium iodide.
This is mostly happens on the american probestart sodium-scandium MH lamps (And on any type of Na-Sc MH lamp generally), which are very not recommended to be operated horizontally, even if they are rated for universal burning.
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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Ash
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| The lamp i used is pulse start (no starting electrode). I will post pics of it later
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dor123
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| Ash: You can also upload videos to Lighting-Gallery (LG). There is a three text boxes in the uploading wizard which you can embed Youtube videos to LG, by insert the address of the youtube video in them.
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Logged
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I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
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