1 2 Questions:
If I put this in this, What effects would that have?
Is it compatible?

And assuming I could do that, Could I do a demonstration of fluorescent tubes with an empty tube just with phosphor?
Where would I get it?

It would be compatible, but don't assume the plastic diffuser will render it safe. Furthermore, you will destroy the plastic very quickly with all that UV.

It would be compatible, but don't assume the plastic diffuser will render it safe. Furthermore, you will destroy the plastic very quickly with all that UV.

How quickly?
And I would be wearing my laser glasses.

I'm not sure. I haven't studied the laser glasses concept enough to advise you on this matter. Others may know more than me on this matter, though.

Laser glasses are a bandpass/bandstop filter. There may be ones that pass the UV in the wavelengths emitted by the G lamp, and ones that resist it - but they still let through somewhat. maybe they drop it low enough to be safe maybe not

Make a demo box out of a small troffer with plain hard glass in place of the normal plastic diffuser

Laser glasses are a bandpass/bandstop filter. There may be ones that pass the UV in the wavelengths emitted by the G lamp, and ones that resist it - but they still let through somewhat. maybe they drop it low enough to be safe maybe not

Make a demo box out of a small troffer with plain hard glass in place of the normal plastic diffuser

Polycarbonate at least.
My laser glasses are OD4 at 190NM to 540NM and 900NM to 1700NM.
I would have to slip the G tube into an empty FL tube, But I don't know how to safely get them.

Quote from: Ash on June 01, 2016, 08:31:14 PM

Laser glasses are a bandpass/bandstop filter. There may be ones that pass the UV in the wavelengths emitted by the G lamp, and ones that resist it - but they still let through somewhat. maybe they drop it low enough to be safe maybe not

Make a demo box out of a small troffer with plain hard glass in place of the normal plastic diffuser

Polycarbonate at least.
My laser glasses are OD4 at 190NM to 540NM and 900NM to 1700NM.
I would have to slip the G tube into an empty FL tube, But I don't know how to safely get them.

Make a shield out of a piece of 1/4" clear polycarbonate (Lexan) and you should be fine.  Just be sure the UV doesn't leak out where someone can look at it.  Shortwave UV from a germicidal tube can give you a nasty sunburn or melanoma.  Just be careful with it.  I have found that germicidal tubes of a particular wattage need to be driven harder than a fluorescent tube of the same wattage.  I guess it's because in a germicidal tube you have to excite the 254nm mercury line, where in a standard fluorescent tube you only have to excite the 365nm mercury line, which takes less power.

IF you run these tubes for a long time, their UV output will decrease because the hard glass will solarize.  if you find a quartz tube, it will not have this problem, but it will be fairly expensive.

Hope that helps.

Steve

Quote from: wattMaster on June 01, 2016, 08:40:38 PM

Quote from: Ash on June 01, 2016, 08:31:14 PM

Laser glasses are a bandpass/bandstop filter. There may be ones that pass the UV in the wavelengths emitted by the G lamp, and ones that resist it - but they still let through somewhat. maybe they drop it low enough to be safe maybe not

Make a demo box out of a small troffer with plain hard glass in place of the normal plastic diffuser

Polycarbonate at least.
My laser glasses are OD4 at 190NM to 540NM and 900NM to 1700NM.
I would have to slip the G tube into an empty FL tube, But I don't know how to safely get them.

Make a shield out of a piece of 1/4" clear polycarbonate (Lexan) and you should be fine.  Just be sure the UV doesn't leak out where someone can look at it.  Shortwave UV from a germicidal tube can give you a nasty sunburn or melanoma.  Just be careful with it.  I have found that germicidal tubes of a particular wattage need to be driven harder than a fluorescent tube of the same wattage.  I guess it's because in a germicidal tube you have to excite the 254nm mercury line, where in a standard fluorescent tube you only have to excite the 365nm mercury line, which takes less power.

IF you run these tubes for a long time, their UV output will decrease because the hard glass will solarize.  if you find a quartz tube, it will not have this problem, but it will be fairly expensive.

Hope that helps.

Steve

Thanks! That should help.

I have found that germicidal tubes of a particular wattage need to be driven harder than a fluorescent tube of the same wattage.  I guess it's because in a germicidal tube you have to excite the 254nm mercury line, where in a standard fluorescent tube you only have to excite the 365nm mercury line, which takes less power.

It is not the spectral lines (standard fluorescents utilize all lines, even the shorter ones, as there is nothing to block them).
The reason is, the phosphor somehow chemically stabilizes the lamp inner atmosphere. And because germicidal lamps gave no such phosphor, the atmosphere changes and so they become more difficult to operate.
The same was observed with the ballast development test lamps (the phosphor is wiped off from the electrode area, so the ballast designer may observe what the filament is doing) - it was the reason, why these are made by wiping off some phosphor and not by otherwise a simpler way of not using the phosphor at all.
And why that? Well, the fluorescent development was focused to make the best performance with a phosphor, the phosphor less tubes were all the time a niche, with very limited knowledge about all the differences. Plus because these are the niche, the makers want to share as much processing and engineering with the mainstream production as possible, so the designs are by far not that well optimized as in the case of the general illumination tubes.

Quote from: srjacob on June 19, 2016, 10:16:21 PM

I have found that germicidal tubes of a particular wattage need to be driven harder than a fluorescent tube of the same wattage.  I guess it's because in a germicidal tube you have to excite the 254nm mercury line, where in a standard fluorescent tube you only have to excite the 365nm mercury line, which takes less power.

It is not the spectral lines (standard fluorescents utilize all lines, even the shorter ones, as there is nothing to block them).
The reason is, the phosphor somehow chemically stabilizes the lamp inner atmosphere. And because germicidal lamps gave no such phosphor, the atmosphere changes and so they become more difficult to operate.
The same was observed with the ballast development test lamps (the phosphor is wiped off from the electrode area, so the ballast designer may observe what the filament is doing) - it was the reason, why these are made by wiping off some phosphor and not by otherwise a simpler way of not using the phosphor at all.
And why that? Well, the fluorescent development was focused to make the best performance with a phosphor, the phosphor less tubes were all the time a niche, with very limited knowledge about all the differences. Plus because these are the niche, the makers want to share as much processing and engineering with the mainstream production as possible, so the designs are by far not that well optimized as in the case of the general illumination tubes.

What about normal fluorescent tubes without phosphor for a MV simulation? It would not be quartz, so it will block the UV, but keep the light of mercury.

Quote from: Medved on June 20, 2016, 11:30:22 AM

Quote from: srjacob on June 19, 2016, 10:16:21 PM

I have found that germicidal tubes of a particular wattage need to be driven harder than a fluorescent tube of the same wattage.  I guess it's because in a germicidal tube you have to excite the 254nm mercury line, where in a standard fluorescent tube you only have to excite the 365nm mercury line, which takes less power.

It is not the spectral lines (standard fluorescents utilize all lines, even the shorter ones, as there is nothing to block them).
The reason is, the phosphor somehow chemically stabilizes the lamp inner atmosphere. And because germicidal lamps gave no such phosphor, the atmosphere changes and so they become more difficult to operate.
The same was observed with the ballast development test lamps (the phosphor is wiped off from the electrode area, so the ballast designer may observe what the filament is doing) - it was the reason, why these are made by wiping off some phosphor and not by otherwise a simpler way of not using the phosphor at all.
And why that? Well, the fluorescent development was focused to make the best performance with a phosphor, the phosphor less tubes were all the time a niche, with very limited knowledge about all the differences. Plus because these are the niche, the makers want to share as much processing and engineering with the mainstream production as possible, so the designs are by far not that well optimized as in the case of the general illumination tubes.

What about normal fluorescent tubes without phosphor for a MV simulation? It would not be quartz, so it will block the UV, but keep the light of mercury.

That may be true, but I also have found that the drive voltage for a BLB tube of a particular wattage is less than a germicidal tube of the same wattage.  The BLB tubes have no phosphor, they just optimize for the 365nm line and the glass is a filter to block the visible light.

And yes, it takes more energy to get the 254nm line because you have to provide more voltage to the Hg electrons to raise them to a higher energy level to get the shorter wavelength.  Ozone-generating tubes that run at around 185nm barely will run on a ballast designed for a fluorescent tube of the same wattage (they are wicked to their environment, however).

see: http://advancedlab.physics.gatech.edu/labs/frankhertz/frankhertz-2.html

Steve

It does take more acceleration voltage to excite the 254nm band, but that does not directly translate to arc voltage. The electron energy comes from the free path length and the electric field within the lamp arc. The thing is, the usual arc voltages are many times higher than the acceleration voltages corresponding to the required energy band, so what happens is, when an electron just happens to cause just the 254nm lines, it collides fewer times than other one, which happens to generate the 360nm (or where exactly it is) line.
Usually the plasma balances itself so, the free path and the electrical field exactly match the radiated lines of the elements inside, the pressure and composition then may affect how many times this voltage stacks up to form the overall arc voltage. So when the atmosphere gets altered, the number of collision changes, as the arc voltage increases.
Plus the difference is not that great in the arc voltage itself, but more in the starting ionization voltage.

But with all fluorescents/germicidals, the mercury discharge generates the same UV radiations, so from the discharge perspective they are designed as exactly the same. The differences are only in the presence and composition of the phosphor (UVA and UVB intentional radiators still use phosphors to convert the harder UV components to this range) or tube wall composition to pass the desired radiation (UV for the germicidal) and block the undesired one (UV for the general lighting types, all but the long wave UV for the "black light")

And with the BLB: You are wrong with assuming these have no phosphors.
Yes, it will be possible to use just filter glass (like with the high pressure mercury), but that would be VERY inefficient (with the MV it is - a 125W arc generates barely 4W of the "blacklight" UVA). The fluorescent BLB's do use phosphors, converting all the short wave UV from the mercury discharge to the desired UVA. As a result the efficiency is way greater than with the high pressure mercury: A 36W T8 BLB emits 8W of the desired UVA, that is way more than the discharge alone generates and majority of it comes from the phosphor conversion.
And because of the phosphor, the arc atmosphere "maintenance" is exactly the same as with normal fluorescents.

It does take more acceleration voltage to excite the 254nm band, but that does not directly translate to arc voltage. The electron energy comes from the free path length and the electric field within the lamp arc. The thing is, the usual arc voltages are many times higher than the acceleration voltages corresponding to the required energy band, so what happens is, when an electron just happens to cause just the 254nm lines, it collides fewer times than other one, which happens to generate the 360nm (or where exactly it is) line.
Usually the plasma balances itself so, the free path and the electrical field exactly match the radiated lines of the elements inside, the pressure and composition then may affect how many times this voltage stacks up to form the overall arc voltage. So when the atmosphere gets altered, the number of collision changes, as the arc voltage increases.
Plus the difference is not that great in the arc voltage itself, but more in the starting ionization voltage.

But with all fluorescents/germicidals, the mercury discharge generates the same UV radiations, so from the discharge perspective they are designed as exactly the same. The differences are only in the presence and composition of the phosphor (UVA and UVB intentional radiators still use phosphors to convert the harder UV components to this range) or tube wall composition to pass the desired radiation (UV for the germicidal) and block the undesired one (UV for the general lighting types, all but the long wave UV for the "black light")

And with the BLB: You are wrong with assuming these have no phosphors.
Yes, it will be possible to use just filter glass (like with the high pressure mercury), but that would be VERY inefficient (with the MV it is - a 125W arc generates barely 4W of the "blacklight" UVA). The fluorescent BLB's do use phosphors, converting all the short wave UV from the mercury discharge to the desired UVA. As a result the efficiency is way greater than with the high pressure mercury: A 36W T8 BLB emits 8W of the desired UVA, that is way more than the discharge alone generates and majority of it comes from the phosphor conversion.
And because of the phosphor, the arc atmosphere "maintenance" is exactly the same as with normal fluorescents.

1) I don't know, but the last BLB tube I broke didn't seem to have a phosphor, but it have the filter glass.

2) All I know on the germicidal lamps, is that about 6 months ago, I built a portable short-wave UV lamp for mineral prospecting.  I used 2 9W PL-S tubes (modified to get access to both filaments and eliminate the starter) and drove them with 2 power supplies from 2 6 volt fluorescent lanterns (easier than designing and building a power supply).  Using a single power supply, the lantern would drive it's 9 watt tube to full brilliance, but it would barely drive the PL-S tube (the arc was really weak and broken up).  I increased the input voltage to 9V, and adjusted the drive resistors on the power supply to increase the voltage on the tube, so now the arc is nice and strong.  Using a bench supply, the original 9W lamp took about 1/2A @6V to fully power the lamp.  For the PL-S tube, it took 9V at 1A to get a good strong arc.  I was somewhat surprised, but when I spoke to a physicist friend, that was his explanation.  My guess is that when you run the germicidal tubes off 120V (or greater), you have enough voltage and current to power the tube, and the tube/ballast combination adjusts for what it needs.

I always use a protective piece of Lexan over the lamp when viewing the arc.

BTW, the lamp works great.  I used a short-wave filter over the lamps.  I don't use the lamp often enough to worry about tube life.

Steve