The Mercury Vapor Lamp 1901

Summary

This script delves into the intricacies of mercury vapor lamps, highlighting their operation principles akin to metal halide lamps. It features the Philips-made Westinghouse Lifeguard lamp, renowned for its longevity and energy efficiency, despite its low color rendering index. The video explores different types, including the clear lamp with its blue-white light, the GE bonus line C lamp with improved color rendering due to phosphor coating, and the smaller wattage lamp with Yttrium Vanadate phosphor for a crisp, cool white light, suitable for both indoor and outdoor applications like streetlights.

Takeaways

• 🌟 The script discusses mercury vapor lamps, a type of light source that operates on the same principle as metal halide lamps.
• ⚡ The lamp functions by passing current through argon gas, heating mercury until it vaporizes and produces light through an arc stream.
• 💡 It doesn't require a phosphor coating to emit usable light, unlike some other types of lamps.
• 🏭 The mentioned model is a 175-watt clear lamp made by Philips, originally a Westinghouse Lifeguard lamp, known for its durability and longevity.
• 🔹 These lamps are energy efficient and known to last up to 50 years, showing their continued viability despite attempts to phase them out.
• 🌈 The light produced is a blue-white color with a color temperature of around 6800 Kelvin, but it has a poor color rendering index (CRI) of about 15.
• ⏱ Mercury vapor lamps take approximately 5 minutes to warm up and will not re-light immediately after being turned off; they need to cool down first.
• 🔌 The clear mercury vapor lamp showcases its operation with visible electrodes and a starting electrode for reduced voltage at startup.
• 🌕 The GE Bonus Line C lamp is an early phosphor-coated mercury lamp that uses a quartz arc tube to transmit UV radiation, which then strikes a phosphor to produce a yellowish-white light.
• 🏙 A later, smaller wattage lamp uses Yttrium Vanadate phosphor, a rare earth phosphor, which improves color and light output, making it suitable for both indoor and outdoor use.
• 💡 The smallest mercury vapor lamp made is 50 watts, which can run on either 40 or 50 watts depending on the ballast, and is often used in street lighting for its crisp-cool white color.

Q & A

What is the operating principle of a mercury vapor lamp?

The operating principle of a mercury vapor lamp is similar to that of a metal halide lamp. The current passes through the argon gas in the tube, heating the mercury until it vaporizes. The mercury vapor then enters the arc stream, and as the lamp warms up, the intensity of the arc increases, producing light.

What is special about the Westinghouse Lifeguard lamp mentioned in the script?

The Westinghouse Lifeguard lamp is considered one of the best mercury lamps ever made, known for its longevity, with some units lasting up to 50 years in service. It is a clear mercury vapor lamp made by Philips after they bought out Westinghouse.

What is the color temperature of the mercury vapor lamp described in the script?

The color temperature of the mercury vapor lamp mentioned in the script is around 6800 Kelvin, which produces a blueish-white light.

How does the color rendering index (CRI) of the mercury vapor lamp affect the appearance of colors?

The mercury vapor lamp has a CRI of about 15, which is not very good for color rendering. As a result, colors may appear unnatural, such as a hand looking green when placed under the lamp.

What are the warm-up and restrike characteristics of mercury vapor lamps?

Mercury vapor lamps take about 5 minutes to warm up when started from cold. If turned off while at full brightness, they will not re-light until they have cooled down for between 5 and 10 minutes.

How does the starting electrode function in a mercury vapor lamp?

The starting electrode in a mercury vapor lamp reduces the amount of voltage necessary to start the lamp. It is positioned close to the main electrode, allowing a small voltage to ionize the gas and start the arc. Once the lamp is running, the arc runs between the two main electrodes.

What is the difference between a clear mercury vapor lamp and a GE bonus line C lamp?

The GE bonus line C lamp, or color improved lamp, is an early phosphor-coated mercury lamp. It has a phosphor coating on the inside of the bulb that glows in an orangish color when struck by the ultraviolet radiation from the arc tube, combining with the blue glow of the mercury vapor to produce a yellowish-white light with better color rendering.

What material is the arc tube of the GE bonus line C lamp made of, and why is it significant?

The arc tube of the GE bonus line C lamp is made of quartz, which is significant because quartz readily transmits ultraviolet light and does not block it, allowing the phosphor coating to glow effectively.

What is the smallest wattage mercury vapor lamp mentioned in the script, and what is its phosphor type?

The smallest wattage mercury vapor lamp mentioned is a 50-watt lamp with a Yttrium Vanadate phosphor, which is a type of rare earth phosphor that improves both the color and light output of the lamp.

How does the Yttrium Vanadate phosphor in the 50-watt mercury vapor lamp affect its light output and color?

The Yttrium Vanadate phosphor increases the light output by about 15% compared to an equivalent clear lamp and provides a crisp-cool white color with better color rendering, making it suitable for both indoor and outdoor use.

What is the significance of the high pressure sodium lamps in the context of mercury vapor lamps?

High pressure sodium lamps are mentioned as an alternative to mercury vapor lamps for street lighting. They have a similar initial warm-up time but can restrike within a minute after the power comes back on, unlike mercury vapor lamps that require cooling down.

Outlines

00:00

💡 Mercury Vapor Lamps Explained

The script introduces a mercury vapor lamp, a favorite light source of the speaker, which operates by passing current through argon gas to heat mercury until it vaporizes, creating an arc stream. Unlike other lamps, it doesn't require a phosphor coating to produce light. The lamp discussed is a 175-watt clear model by Phillips, originally a Westinghouse Lifeguard lamp, known for its longevity and energy efficiency. It emits a blue-white light at 6800K, but with a low color rendering index (CRI) of about 15, making colors appear unnatural. The lamp takes about 5 minutes to warm up and requires cooling down before it can be restarted after being turned off. The clear design of the lamp allows for a clear view of its operation, including the two operating electrodes and a starting electrode, which facilitates the initial arc strike. The script also mentions a GE bonus line lamp, known as a 'C lamp,' which uses a phosphor coating to produce a yellowish-white light with better color rendering.

05:01

🌟 Evolution of Mercury Vapor Lamps

The second paragraph delves into the evolution of mercury vapor lamps, focusing on a smaller, 50-watt model with improved phosphor technology. This lamp uses Yttrium Vanadate, a rare earth phosphor, which not only enhances the white color of the light but also increases its output by about 15% compared to the clear lamp. The improved color rendering makes these lamps suitable for indoor use, and they are often found in street light fixtures that emit a crisp, cool white light. The paragraph also notes that these lamps were prevalent before the advent of high-pressure sodium lamps and can still be found in some fixtures, with wattages ranging from 175 to 1000 watts depending on the fixture.

Keywords

💡Mercury Vapor Lamp

A mercury vapor lamp is a type of gas-discharge lamp that uses mercury vapor to produce light. It is a key subject of the video, illustrating the lamp's operating principle, which involves the current passing through argon gas to heat up mercury until it vaporizes. The script mentions this lamp as one of the favorite light sources of the speaker, emphasizing its longevity and energy efficiency.

💡Argon Gas

Argon gas is an inert gas used in the mercury vapor lamp to facilitate the heating process of the mercury. It is essential in the lamp's operation as described in the script, where the current passes through the argon gas, which then heats the mercury until it vaporizes, contributing to the lamp's light production.

💡Phosphor Coating

Phosphor coating is a substance applied to the inside of a lamp to convert ultraviolet light into visible light, improving the color and quality of the light emitted. The script discusses the use of phosphor coatings in mercury vapor lamps, particularly in the 'C lamp' or 'color improved lamp,' which enhances the color rendering compared to clear lamps.

💡Color Rendering Index (CRI)

The Color Rendering Index (CRI) is a measure of a light source's ability to reveal the true colors of objects in comparison to a natural light source. The script mentions the CRI of the mercury vapor lamp as being about 15, indicating poor color rendering, which is demonstrated by the greenish appearance of a hand under the lamp's light.

💡Kelvin

Kelvin is a unit of measurement for the color temperature of light, indicating the perceived color of light emitted by a source. The script describes the mercury vapor lamp's color temperature as around 6800 Kelvin, which is a cool, blue-white light, contributing to the lamp's distinctive appearance.

💡Warm-up Time

Warm-up time refers to the period required for a lamp to reach its full brightness after being switched on. The script specifies that mercury vapor lamps take about 5 minutes to warm up, which is a characteristic of these lamps and similar to metal halide lamps, impacting their practical use in certain applications.

💡Restrike Time

Restrike time is the interval needed for a lamp to relight after being turned off. The script explains that mercury vapor lamps, once at full brightness, will not re-light immediately if turned off, requiring a cool-down period of 5 to 10 minutes, unlike high-pressure sodium lamps which restrike more quickly.

💡Operating Electrodes

Operating electrodes are the components in a gas-discharge lamp where the electrical discharge occurs. The script describes the clear mercury vapor lamp having two operating electrodes, which are essential for the lamp's function, as the arc runs between these electrodes once the lamp is operating.

💡Starting Electrode

A starting electrode is a thin wire used to initiate the ionization of the gas in a lamp, reducing the voltage necessary to start the lamp. The script mentions that the starting electrode is not visible in the clear mercury vapor lamp but is crucial for the lamp's ignition process.

💡Yttrium Vanadate Phosphor

Yttrium Vanadate is a type of rare earth phosphor used in lamps to improve the color and efficiency of light output. The script describes a mercury vapor lamp using Yttrium Vanadate phosphor, which provides a crisp-cool white color and better color rendering, making the lamp suitable for both indoor and outdoor lighting.

💡Ballast

A ballast is a device used to regulate the electrical current to a lamp, especially in gas-discharge lamps like mercury vapor lamps. The script refers to a 50-watt mercury vapor lamp that requires a ballast to operate, indicating the importance of this component in the lamp's function.

Highlights

Mercury vapor lamps are one of the favorite light sources due to their operating principle similar to metal halide lamps.

These lamps heat up mercury until it vaporizes, producing light without the need for a phosphor coating.

The Phillips Westinghouse Lifeguard lamp is a renowned mercury lamp known for its longevity, lasting up to 50 years in service.

Despite attempts to phase them out, mercury vapor lamps remain a viable and energy-efficient white light source.

The lamp emits a blue color light at around 6800 Kelvin, but has a low color rendering index (CRI) of about 15.

Mercury vapor lamps take about 5 minutes to warm up and will not re-light immediately after being turned off.

The clear mercury vapor lamp showcases the operation with two visible electrodes and a starting electrode.

The starting electrode reduces the voltage necessary to start the lamp by ionizing the gas.

The arc in the lamp runs strictly on mercury vapor, without halide salts or other additives.

The GE Bonus line C lamp is an early phosphor-coated mercury lamp dating back to 1963.

The C lamp uses a phosphor coating similar to fluorescent lamps, enhancing the light's color rendering.

The phosphor coating in the C lamp produces an orangish glow, combining with the blue glow for a yellowish-white light.

A later type of mercury vapor lamp uses Yttrium Vanadate phosphor for a whiter and more efficient light output.

The 50-watt mercury vapor lamp with Yttrium Vanadate phosphor provides a crisp-cool white light suitable for indoor use.

Street light fixtures using deluxe white lamps with Yttrium Vanadate phosphor emit a crisp-cool white color.

Different wattages of mercury lamps are available, from 40 to 1000 watts, depending on the fixture requirements.

Transcripts

What we have here

is one of my favorite light sources

It's a mercury vapor lamp,

It's operating principle is the same

as the metal halide, the current passes through the argon gas in the tube

heats up the mercury until it vaporizes

and mercury vaporizes in to the arc stream

and the intensity of the arc increases

as the lamp warms up

and the arc produces light by its self,

so it's doesn't need a phosphor coating to produce usable light.

This particular model is 175 watts,

clear, and it's made by Phillips

but it is the good old Westinghouse Lifeguard lamp because Philips bought out Westinghouse

and one of the best mercury lamps ever made in history,

These things have been known to last as much as 50 years in service

This lamps are a venerable light source

So these lamps still have

viability today even know they tried to phase them out

and they are indeed an energy efficient white source

The lamp produces kind of a pretty color,

it's a blue color,

it's around 6800 degree Kelvin

color temperature

and it's a pretty blue white,

not very good color rendering

it only has CRI of about 15

if you put hand underneath it

when it's lit, your hand will look green underneath it

but it's still good enough to see colors under like a car parked under it

Another thing about mercury lamps is they take about 5 minutes to warm up

when they are started from cold

and once they are at full brightness, if you shut them off even for a second

and turn them back on,

they will go out and will not re-light, until they cool down for between 5 and 10 min.

Same thing with metal halide lamps,

high pressure sodium lamps

have the 5 minutes initial warm up

or if you shut them off when they are hot they restrike within a minute

after the power comes back on

The clear mercury vapor lamp

really shows

how the lamp operates,

similar to the metal halide it's got two operating electrodes which are clearly visible

and a starting electrode which is much thinner you cannot really see it,

it's a tiny little piece of tungsten wire.

And the starting electrode is there by the way

because it's reduces the amount of voltage necessary to start the lamp,

because, it's so close to the other electrode, the main electrode

that it's set up little voltage between it and strikes the gas,

once the gas ionizes the arc strikes in the lamp and it's runs,

so it's only there for starting and once the lamp its running,

the arc runs between this two electrodes

The arc runs to strictly mercury vapor there's nothing else, no halide salts,

anything like that in the lamp

So, it's strictly an mercury discharge at high, medium-high pressure inside the arc tube at high intensity

This is a GE bonus line

This lamp is known as an C lamp or color improved lamp

and is one of the earlier phosphor-coated mercury lamps

and this one dates back to 1963,

the phosphor coating on the inside the bulb is similar to the phosphor coating used at the fluorescent lamps

and because of the arc tube inside is made of the quartz,

quartz transmits ultraviolet light readily its doesn't block it

So the arc tube gives off quite a bit of UV radiation when its in operation,

so that UV strikes a phosphor and makes it glow

and in this case, this phosphor glows in orangish color and add that to the blue glow of the mercury vapor

and you get a lamp that's got a beautiful yellowish white color

and it's much better color rendering, object's lighted by it show color better,

puts out a little less light then the clear lamp, but what it loses in light output it gains in color quality

And then is a later type which I have here

and a smaller wattage and this one has the auxiliary gear to run it,

as well the ballast

This one is an 50 watt mercury vapor, which is the smallest size they ever made,

it can run on either 40 or 50 watt depending on the ballast that it runs on

and the phosphor on this lamp is as you can see is a whiter color

because its a different phosphor, its Yttrium Vanadate phosphor

and it's actually a type of rare earth phosphor

and this phosphor is much more efficient that the old C-phosphor.

This not only improves the color of the white with the Yttrium Vanadate,

but it increases the light output, this lamp actually puts out about 15% more light

that the equivalent clear lamp,

while at the same time providing a crisp-cool white color of light almost like a cool white fluorescent,

with pretty good color rendering so you can even use them indoors

A lot of street light fixtures use these deluxe white lamps

Up until high pressure sodium came around and there's still some of them in use and there are easy to identify,

any street light you see that light up a crisp-cool white color has this type of mercury lamp in it with the Yitrium Vanadate phosphor,

probably in a bigger voltage 175, 250, 400 maybe 700 or even 1000 watts

depending on the fixture.