Why the British neon floodlight lamps were called NE/H, if they can work in any position (They have gas, not metals)?

Who said they can work in any position..? I assume the manufacturers knew the specifications of their own lamp..?

As these lamps contains gas and not metal vapour, and they are linear low intensity lamps (Compared to short-arc xenon lamps), they shouldn't lose their performance or shorten their life at burning position other than horizontal.

Like I said, I am assuming that the manufacturers had a reason for marking them /H, but as they are no longer in business, we can't ask them. Linear floodlights are usually mounted horizontally anyway.

James, Max..?

Why the British neon floodlight lamps were called NE/H, if they can work in any position (They have gas, not metals)?

The temperature distribution is not only about maintaining an internal atmosphere. It is also about the ability of the used materials and their assemblies to operate at that temperatures (so e.g. the metal parts won't start outgassing, seal cracking,...; what happens depends pretty much on the exact assembly process used for production).

In horizontal position of a long tubular lamp pretty much the whole tube length get a cool, fresh air for its cooling...
Heat rises. So when operated vertically, the same air would flow around the whole tube. So the bottom part will warm that air up, this hot air will then flow around other part of the bulb that then would not be cooled down as it should and so may overheat.

That makes perfect sense, it's all down to the laws of thermodynamics. 

The temperature distribution is not only about maintaining an internal atmosphere. It is also about the ability of the used materials and their assemblies to operate at that temperatures (so e.g. the metal parts won't start outgassing, seal cracking,...; what happens depends pretty much on the exact assembly process used for production).

In horizontal position of a long tubular lamp pretty much the whole tube length get a cool, fresh air for its cooling...
Heat rises. So when operated vertically, the same air would flow around the whole tube. So the bottom part will warm that air up, this hot air will then flow around other part of the bulb that then would not be cooled down as it should and so may overheat.

I've never seen this phenomenon with fluorescent lamps that are installed vertically, like the T5 lamps inside the signs at the Metronit bus stations.

They operate at a much lower temperature where they won't be adversely affected.

Why the NE/H operates at higher temperature than fluorescent lamps? It have a neon gas, not liquid or amalgam mercury to vapourize?

This is a not a fluorescent lamp, you can't compare it with one. For a start, the cathodes are continuously heated, that's why there are the bulbous sections around each one.

And with the American rapid-start ballasts, the lamp electrodes also continuously heated, and the lamps don't have bulbous sections around the electrodes.

Hello,

The explanation of Medved is a good one. I personally would have also thought about convection in the lamp as it is a narrow long tube. Many medium and high pressure discharge lamps that feature long arc tubes are designed for vertical application. I do not know if that is the primary reason with this lamp. Also we do not know the exact fill pressure of this lamp. The Lamp is however  loaded with 6Amps, so I assume the plasma is rather hot, allowing possibility for convection.

Notherless these and also the Claude Obsta lamp for obstruction are very fascinating and collectable which, which I hope I will at some point also own. However as mentioned they are ridiculously rare. 

Also, the assumption that a discharge lamp that is only filled with a noble gas con be run in any direction is pure garbage. Again a fastly tipped sentenced without thinking how powerfull the wording is used.

The most common example was mentioned by the Author himself. The super high pressure xenon short arc lamp can generally be only operated horizontally not vertically. This is due to the very high plasma tempretur of several thousand degrees, which would lead to convection currents distorting the Discharge. These lamp can only be run vertically when the the discharge is locked in position by an external force brought in from outside, generally a magnetic field.

Xenon Long Arc Lamps like the Osram XQO-Gigant were only specified for vertical application

Krypton Arc lamps lamps are generally rated for horizontal application

These lamps all feature a high loading compared to cold cathode noble glass lamp or negative discharge glow lamps, which is also common with the Ne/H lamp.



Edit:
 It took me some time to write this. the conversation "evolved". While I would generally consider things like the bang head picture as spam however -sadly- it is adequade here.

The topic was about why a noble gas filled lamp may always be able to be burned universal. The argumentation did not work out. That argumentation collapsed. Then it was stared to compare it to a fluorescent lamp, that failed due to the text above. The loading of a fluotube is different than the loading of the Ne/H lamp.

Fluorescent cathodes are also permanently heated, however of thrue the discharge itself. The power dissipation is therefore much lower the on the Ne/H lamp, which is heated at several amps via a Filamant Transformer.

 
Best regards,

Alex

A very sound explanation, Alex. Thank you.

Dor, we have actual lamp engineers here, you need to listen to them and not assume you know it all when you DON'T! Yet you continue to argue with them who have more experience than you! This needs to stop! You need to not act like a know-it-all!