If a Mercury Vapor Bulb has light, does that mean.

[anthony]

Hi, if I switch on the Mercury Vapor bulb, and it has light, does that mean that its UVB producing filament or whatever is intact?

I don't mean a bulb that has been used for a long time, but just a new out of the box bulb, used for a day.

The reason I ask is, I had switched my self ballastes mercury vapor bulb, installed today, for a few hours. It got hot. I switched it off to reposition it, and in a few minutes, switched it back on.
When it went on, there was a slight sound like that when you switch on a florescent light, which lasted one second. The light gives off light and heat as normal.

Then I read that if these lights are switched on again before they cool off completely, that they would burn out.

What I need to know is, WITHOUT a UVB meter, and assuming it hasn't decayed over a long time, (I'm talking about sudden burnout from jostling or switching on and off here), if the light switches on ok and emits light, that it is still emiting UVB?

Can you "break" a filament unknowingly so that it still gives off light and heat but not UVB?

[IguanaKing]

Unfortunately, the only way to know for sure if a UVB lamp of any type is emitting sufficient UVB is to test it with a meter. The proper operation of the ballast is also critical to how much UVB the lamp produces, and you usually won't be able to tell if its ballast is any good by looking at the light. For example, I tried putting my new UVB fluorescent tubes into an existing fixture, and got readings of around 50uW/cm^2 at 18", which is ok, but not what the tubes were rated for. The next day I bought a new fixture and put the same tubes in that. Shortly after starting, I had 200uW/cm^2 at 18", and as they stabilized, it went to 155. So, the ballast difference between the two fixtures was pretty significant. I don't know if it was the age of the old fixture, or if it was just that the ballast in it was never any good to begin with. But, I couldn't really see a difference between the two with my eyes. I realize its not a Mercury vapor bulb that I'm talking about, but the same principle applies.

[anthony]

I'm more interested to know if hearing a sound when turning it on indicates the bulb is working at all, rather than whether it is performing at peak performance.

[IguanaKing]

Actually, that's what I meant to say. Some of our members have gotten brand new mercury vapor bulbs that barely put out any UVB at all due to either manufacturing defects or transport damage. These were all bulbs that appeared in every other way to be operating as they should, but weren't actually doing the job they were intended to do.