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Quick HPS warmup appearance question

T

Travis Evans

Jan 1, 1970
0
Observing various HPS installations, I've noticed that some lamps turn
their yellow-orange sodium color very early in warmup, whereas other
lamps initially look white like a phosphored mercury or a metal halide
lamp and don't reach their final color until much later in warmup.

I'm just curious what accounts for the difference in behavior. Is it
primarily just dependent on the lamp brand or type, or is it age-related?
 
D

Don Klipstein

Jan 1, 1970
0
Observing various HPS installations, I've noticed that some lamps turn
their yellow-orange sodium color very early in warmup, whereas other
lamps initially look white like a phosphored mercury or a metal halide
lamp and don't reach their final color until much later in warmup.

I'm just curious what accounts for the difference in behavior. Is it
primarily just dependent on the lamp brand or type, or is it age-related?

Although age makes a major difference as I. Galidakis mentions, there
are differences among HPS lamps.

Most HPS lamps 100 watts and less are lower voltage types. So are some
150W ones (S55) that I expect more in countries with 120V lines.

They require a lower total pressure than the higher voltage types
do. However, they require a similar pressure component of sodium vapor
alone, in order to have the desired spectral radiation characteristics.
So, the mercury content is cut back in comparison to the higher voltage
types.

There are other differences among lamps, which are minor as far as I
know. The most significant of these appears to me to be the wattage.
Lamps with higher power reaching the discharge column, per square
centimeter of arc tube surface around the discharge column, tend to have
higher arc temperatures. Mercury is more sensitive than sodium to
temperature for producing visible light.
I notice some trend of greater presence of mercury spectral lines in
higher wattage HPS lamps, and lesser in lower wattage HPS lamps. I
notice the rate of this trend being more in lamps 70 watts and less, and
less in lamps over 150 watts.
 
D

Don Klipstein

Jan 1, 1970
0
Don Klipstein wrote:
[snip]
There are other differences among lamps, which are minor as far as I
know. The most significant of these appears to me to be the wattage.

There is also the issue of retrofit HPS. If I recall right, regular HPS
lamps contain xenon as buffer gas and a sodium-mercury amalgam.

Retrofit HPS lamps which are designed to run on HPM circuits contain neon
as a buffer gas

Specifically, the common neon-argon mixture of 99.5% neon .5% argon.
This is used in "standard intensity" neon glow lamps such as NE-2, while
"high intensity" neon glow lamps such as NE-2H and most truly neon signs
have pure neon.

The Ne-Ar mixture has a main glow discharge column glowing a slightly
pinkish or "strontium-like" orangish-pinkish red in normal HPS starting
duty.
At reduced currents, the color shifts to more purplish. At 1 milliamp
(very far from normal usage), the main discharge column has a more
argon-like color close to lavendar - and the ends of the arc tube glow
with the very different orange color of cathode/negative glow of a glow
discharge in this gas mixture. This orange color is like that of "true
Ne-2" lamps, appearing slightly yellowish in comparison to the purplish
glow of the main discharge column. At one time I thought this was sodium
glow, until I tried a diffraction grating and found it was neon. The
sodium-similar-color yellow line of neon is strong here.
I even used a diffraction grating to view a hot (recently used normally)
retrofit HPS lamp operated at 1 mA as it cooled. At some time, I saw the
585.25 nm neon line (and other neon lines) fade in, followed by the
589/589.6 nm sodium lines fading out. The yellowish orange end glow of a
retrofit HPS lamp operated at 1 milliamp is from neon in the neon-argon
mixture, even though the main discharge column glows with a more argon-like
color at such low current.
and have a starting electrode wound around the alumina discharge tube
which initiates the discharge through a neon glow discharge, so their
starting behavior is quite different from that of regular HPS lamps.
When they start, they glow red, from neon, until sodium kicks in.

I think retrofit HPS lamps also contain a mercury-sodium amalgam, so
"eventually" their behavior near end of life should be asymptotically
similar to that of regular HPS lamps, although I've never seen an aged
retrofit HPS.

I have seen many retrofit HPS lamps in USA. I even have a few aged
ones.

In my experience, these usually have even more mercury than non-retrofit
HPS lamps have. They require even higher voltage drop than non-retrofit
HPS 200-400W and higher-voltage 150W (S56). At times I have even seen
some retrofit HPS lamps in new condition change from red to a mercury-like
color as they started to warm up.
These were popular in the States when I was there. We don't have them
here in Eu.

My experience is from the States. It appears to me that the popularity
of retrofit HPS lamps (mostly H39 and H33 ballast compatibility) has been
decreasing somewhat as the decades go by, in favor of S56 and S51.
 
A

Andrew Gabriel

Jan 1, 1970
0
Don Klipstein wrote:
[snip]
There are other differences among lamps, which are minor as far as I
know. The most significant of these appears to me to be the wattage.

There is also the issue of retrofit HPS. If I recall right, regular HPS lamps
contain xenon as buffer gas and a sodium-mercury amalgam.

Retrofit HPS lamps which are designed to run on HPM circuits contain neon as a
buffer gas and have a starting electrode wound around the alumina discharge tube
which initiates the discharge through a neon glow discharge, so their starting
behavior is quite different from that of regular HPS lamps. When they start,
they glow red, from neon, until sodium kicks in.

I think retrofit HPS lamps also contain a mercury-sodium amalgam, so
"eventually" their behavior near end of life should be asymptotically similar to
that of regular HPS lamps, although I've never seen an aged retrofit HPS.

These were popular in the States when I was there. We don't have them here in
Eu.

We had them in the UK. They used an internal glow bottle as an
ignitor, combined with resulting back-EMF from the series ballast.
I don't remember a neon glow at startup.

They ceased to be available a long time ago.

Standard internal ignitor HPS lamps are still available here,
but I think the internal ignitor versions only come in low power,
whereas the retrofit ones were 250 and 400W replacements, running
at slightly less power (IIRC, the 400W retrofit ran at something
like 350 or 375W).
 
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