Gas Mantle Lamp Data

A gas mantle lamp produces light using the candoluminescence effect and not by black body radiation where a certain color temperature applies.

The colour of the flame depends upon the elements and compounds in the gas being burnt, and not the black body colour temperature.

Friends,

Your replies have occurred as rapidly as I had expected, based on years of being part of CR4. You are correct that a black body colour temperature is a poor fit to the light output of a Welsbach or similar gas lamp mantle. Regardless of how it creates light it does so in a visible range with the ability to appear "white". Every electrically-created light source, regardless of the physics involved in the creation of the light has been described with a corrolated colour temperature (CCT). "White" LEDs do not have a black body spectral response because their color is a combination of many spectral bands created mostly by fluoresence or phosphorescence of the coating in front of the LED (where the UV and near UV light from the LED is absorbed and then emitted by the action of electrons transitioning between different energy levels in the rare earth compounds used). This is the same method used in fluorescent, induction, and some other light sources. Each of these has been described with a CCT, such as ranging from 2,700 to 6,000 K for an LED (depending on the phosphor mix used in a "white" LED). Even LED's that use a blend of red-green-blue individual sources to produce a "white" light can be given a CCT.

Surely someone can tell me what an approximate or equivalent CCT is for a gas mantle.

Not if the pursuit were pure folly.

"... Not if the pursuit were pure folly. ..."

Using 'if'-'were' specifies the subjunctive, meaning conditions of unreality or disbelief of stated conditions.

What indication is there of the pursuit not being pure folly?

Quite.

Any thoughts as to what Hydrogen would produce, which burns colorless were used?

Thank-you, Rixter. I believe I had seen and read the source you quoted, but had missed the CCT value cited in that article. I appreciate the help. Now, does anybody know the Color Rendering Index (CRI) for the gas mantle lamp?

--JMM

Maybe you can read data from the spectral distribution above and use an online calculator.

The graphic is not to be trusted.

The graphic indicates visible light falls in a range of wavelengths from roughtly 0.4 mm to 0.8 mm. That is not correct. It is off by several orders of magnitude. Visible light has a range of wavelengths from roughly 0.0004 mm to 0.0008 mm.

Interesting. Obviously a typo, "mm" should be "μm".

..." colour temperature (2,700 to 2,800K) • The LEDs chosen for this project are 2,700K almost precisely matching the light from a gas mantle"...

https://www.slideshare.net/theilp/pls-2017-led-there-be-gas

Thanks for the confirmation, SE. But does anyone have a value for the CRI of a gas mantle lamp? Based on the spectral output I suspect it is fairly high, but a guess isn't what I need.

--JMM

I would say it varies according to several variables...

..." The mantle is a roughly pear-shaped fabric bag, made from silk, ramie-based artificial silk, or rayon. The fibers are impregnated with rare-earth metallic salts; when the mantle is heated in a flame, the fibers burn away, and the metallic salts convert to solid oxides, forming a brittle ceramic shell in the shape of the original fabric. A mantle glows brightly in the visible spectrum while emitting little infrared radiation. The rare-earth oxides (cerium) and actinide (thorium) in the mantle have a low emissivity in the infrared (in comparison with an ideal black body) but have high emissivity in the visible spectrum. There is also some evidence that the emission is enhanced by candoluminescence, the emission of light from the combustion products before they reach thermal equilibrium.^[2] The combination of these properties yields a mantle that, when heated by a kerosene or liquified petroleum gas flame, emits intense radiation that is mostly visible light, with relatively little energy in the unwanted infrared, increasing the luminous efficiency.

The mantle aids the combustion process by keeping the flame small and contained inside itself at higher fuel flow rates than in a simple lamp. This concentration of combustion inside the mantle improves the transfer of heat from the flame to the mantle. The mantle shrinks after all the fabric material has burned away and becomes very fragile after its first use."....

https://en.wikipedia.org/wiki/Gas_mantle

The best you can do is an average range, then you might select a median point if acceptable...

Candoluminescence is the light given off by certain materials at elevated temperatures (usually when exposed to a flame) that has an intensity at some wavelengths which can, through chemical action in flames, be higher than the blackbody emission expected from incandescence at the same temperature.^[1] The phenomenon is notable in certain transition-metal and rare-earth oxide materials (ceramics) such as zinc oxide, cerium(IV) oxide and thorium dioxide.

Yep. The professionals who work in the lighting industry determine the color rendering index (CRI) by a standardized method that involves comparing the appearance of 15 and sometimes many more standardized color surfaces when illuminated by the test light source compared to when illuminated by a standardized source. The data from this are then put into the proper formulas to generate a CRI. I suspect that since gas mantles are almost exclusively used for historical appearance in outdoor lanterns and with camping lanterns, the interest in determining the CRI is pretty well non-existent. (CRI and color temperature are very different measurements.)

Doesn't hurt to ask, however.

--JMM

Maybe these guys would know...?

https://americangaslamp.com/product-support/faqs/

Thanks SE for the suggestion. Their FAQs say nothing on the topic and the very kind person who answered the phone is passing my question on to their technical people. Considering their market emphasis, I strongly doubt they have the answer to my question.

--JMM

Yeah, but they might know somebody who does....

I appreciate everyone's input. If I have time (and I don't) I would follow Rixter's suggestion and read the data from the graph (or possibly find the tabulated data in the original source) and use the on-line calculator. Y'all take care and continue to do good work.

--John M.

I'm sorry - I don't have that information exactly, partly because it did vary between mantle manufacturers, depending on the precise formulation of the metal salt solution in which the mantle was dipped (mainly cerium, but with varying amounts of thorium, beryllium, aluminum and/or magnesium), and they don't seem to have published much. I believe that it might be 'sort of' between 3500 and 5000K, but it is rather confounded by the preponderance of blue, green and yellow components over red, which make it greener than 'black body' light of any colour temperature - in other words the CRI is pretty low. The reason it can be interpreted as white, is probably that there are so many individual spectral lines - but it still doesn't quite conform to a specific colour temperature.