# Low pressure sodium?



## strideredc (Sep 1, 2007)

I was reading that these are the most efficient form of bulb?

Is there a form that’s mag fitting size??? Sort of like that Welch and allen did with the 10w HID?

Anyone…


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## Gunner12 (Sep 1, 2007)

Low pressure sodium lamps are the orange/yellow colored lights you see in street lamps.

Would you really want one in your flashlight?


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## FILIPPO (Sep 1, 2007)

yeah!
you are right! these lams haven't got a good CCT but they are rated at 200 Lumns/Watt!!
I think I want a 10W lamp in my flashlight...:devil:


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## yuandrew (Sep 1, 2007)

The smallest commercially available LPS lamp I've seen is 18 watts. I think it was about 2 and a 1/2 inches in diameter and around 10 inches long. The discharge tube was a smaller U shaped tube going through the length of the lamp. Not really a point source for throw but it will flood everything in a orange-yellow color that you shine it on.

How would you power it ? 
Most LPS ballasts would probably run on 120volts AC so it will require a power inverter of some sort. There are a number of companies though that make DC LPS ballast for the renewable energy/solar powered outdoor lighting market though. Thin-Lite (who I am familiar with for fluorescent lights used in RV and Boat applications) has one. Search for the model LPS-118LT.

A LPS lamp will operate like HID; when turned on, it will take a few minutes to warm up to full brightness.


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## Illum (Sep 1, 2007)

sodium lamps are cheap, efficient, and popularly used...but the tint isn't exactly very useable....but much much better than whats emitted by mercury lamps:devil:


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## strideredc (Sep 2, 2007)

naaa, it would be like my mag just the second before it dies!!!

could be good for a camping lamp if it could be run off 4 d cells...???


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## FILIPPO (Sep 2, 2007)

do anyone know where can I found some of these sodium/mercury vapor lamps?

I have searched with google but I haven't found anything...:candle:


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## FILIPPO (Sep 3, 2007)

after a good search I've found a good place where to buy some HIGH pressuere sodium lamps...(in italy) 
I think that they are pretty good efficent compared to a normal halogen lamp...I may probably buy one of these high pressure 400W sodium lamp and make an adaptator to fit it in a normal 220V spotlight that uses 500W tubolar halogen lamps...

-Osram 400W high pressure sodium lamp ---> 48000L
-Philips tubolar 1000W halogen lamp-------->26500L

:devil:


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## Minjin (Oct 14, 2007)

Finding low pressure sodium lamps (for a reasonable price) seems to be just about impossible. I've had it on my ebay watch list for a few years now and I'll occaisionally get hits on bulbs or very expensive fixtures but they are few and far between.


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## mezzman (Oct 17, 2007)

You can get LPS lamps at the link below:
http://www.prolighting.com/bulbs-hid-low-pressure-sodium.html


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## Minjin (Oct 17, 2007)

mezzman said:


> You can get LPS lamps at the link below:
> http://www.prolighting.com/bulbs-hid-low-pressure-sodium.html


Bulbs don't do much good without something to plug them into.


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## TorchBoy (Oct 17, 2007)

FILIPPO said:


> these lams haven't got a good CCT but they are rated at 200 Lumns/Watt!!





yuandrew said:


> The smallest commercially available LPS lamp I've seen is 18 watts.





mezzman said:


> You can get LPS lamps at the link below:
> http://www.prolighting.com/bulbs-hid-low-pressure-sodium.html



The 18W bulb is "only" 100 lm/W.

I like the red neon-light colour they have before they heat up and the sodium gets going.


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## EricB (Nov 3, 2007)

If you could get a common 590mm amber LED flashlight bulb, that's the same exact color.


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## The_LED_Museum (Nov 4, 2007)

I think LPS lamps emit mainly the sodium line at ~589.4nm - a very orangish-amber color.
And LPS bulbs have a very poor CRI (color rendering index)...the best thing about them is the very reddish neon glow (the gas fill is primarily neon & argon) they generate while in the earliest stages of their warmup cycle.


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## jtr1962 (Nov 5, 2007)

Compared to some LEDs the conversion efficiency isn't as good. The 180 LPS lamp gets 167 lm/W _but_ 590 nm light has a luminous efficiency of 517 lm/W. Hence the efficiency is only 32%. If we could make a 590 nm yellow LED with efficiency on par with the best blue emitters (~50%), it would be in excess of 250 lm/W.

For now LPS is king of the hill but LED will soon surpass it, and with decent white light, not monochromatic yellow.


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## mzzj (Nov 17, 2007)

strideredc said:


> could be good for a camping lamp if it could be run off 4 d cells...???



could be good if you are completely color-blind. Really poor CRI reduces contrast and you need lot more light to be able to see as well as with white light source. Luckily lp-sodiums on streets are mostly replaced with hp-sodiums and mercury lamps.


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## The_LED_Museum (Nov 17, 2007)

The last time I saw LPS lamps in streetlighting was around 1981; they were found lighting the road near Floyd Dryden Jr. High school in Juneau AK. USA.
I saw one near the Greyhound bus depot in Portland OR. USA in late-May 2006; but I did not have my spectrometer handy at the moment. :green:


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## made in china (Nov 18, 2007)

There is an LPS lamp on display at the Smithsonian Museum. They even have a diffraction lens to prove that it is a monochromatic light source.

I remember Southern California used LPS for street lighting in the past. Not sure if they still do. As a kid I was quite impressed by the long, sleek fixtures that looked so modern.


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## EricB (Nov 18, 2007)

Massapequa Park, NY.

Also, in the late 70's; NYC began putting them on some streets, in industrial areas; and all along the Henry Hudson Parkway, stemming from Manhattan's West Side Highway. They also began appearing around some housing projects. This was the first time I had seen them; and with the recent rapid transition from mercury to hps fresh in my mind; I feared this would now be the next step. 
But most of these have since been replaced with standard hps. You will occasionally still find a lps or two on a back street, and they are common on underpasses, and on high rise rooftops. Some of the river tunnels had them too (and it was amazing to be riding through, completely bathed in this light, and even a red shirt is now completely dulled down into almost nothing!). The tunnels now seem to have gotten halides and white SON's.


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## HEY HEY ITS HENDO (Nov 18, 2007)

made in china said:


> There is an LPS lamp on display at the Smithsonian Museum. I remember Southern California used LPS for street lighting in the past


 lol, virtually all of the street lighting here is STILL low pressure sodium, known also as SOX,
as high pressure sodium is known also as SON
mercury MBF
metal halide HQI
i haven`t got a clue what the acronyms stand for though


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## 2xTrinity (Nov 18, 2007)

> There is an LPS lamp on display at the Smithsonian Museum. They even have a diffraction lens to prove that it is a monochromatic light source.
> 
> I remember Southern California used LPS for street lighting in the past. Not sure if they still do. As a kid I was quite impressed by the long, sleek fixtures that looked so modern.


I'm in the San Diego area, and the majority of the lighting where I live is a weird blend between low-pressure sodium (good for astronomy, the worst for color rendering) and Metal Halide (good for color rendering, the worst for astronomy...), which in practice is sort of like the worst of both worlds. IMHO they'd be best off ditching the sodium lamps and sticking to the halide lamps _alone_ at lower intensities. Or just use the newer more "incandescent like" high pressure sodium lamps most other places seem to be using.


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## jtr1962 (Nov 18, 2007)

HEY HEY ITS HENDO said:


> lol, virtually all of the street lighting here is STILL low pressure sodium, known also as SOX,
> as high pressure sodium is known also as SON
> mercury MBF
> metal halide HQI
> i haven`t got a clue what the acronyms stand for though


 
SOX=sodium oxide

SON=variation of "sun" (used on account of the somewhat better color rendering of HPS compared to LPS)

MBF=methylbenzoylformate?

HQI=no idea but it's obvious the H stands for halide


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## circline guy (Dec 10, 2007)

I remember about 29-30 years ago, when I was in college...sodium vapor lights were new here and just being installed in the downtown part of the city (Denver) where I lived (this college was in the suburbs). The subject got brought up by some of my classmates (ages late 20's-early 30's). One of the women called them 'rape lights'. She hated them. I guess their dim, monochromatic amber glow made her feel unsafe. Whenever I pass through some poorly lit area at night, illuminated only with those orangy bulbs,I can't help but think: 'rape lights'.


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## PhotonWrangler (Dec 10, 2007)

Back in the early 80s I bought a couple of sodium lamps that were designed to be direct retrofits for mercury-ballasted fixtures. I put them in a couple of parking lot fixtures with the intention of improving the general visibility at night.

They turned out to be way too yellowish. One observer even commented "What's with the yellow bulbs?" So we took them out and put the MV lamps back in. 
:sigh:


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## Silverliner25s (Dec 31, 2007)

There are still LPS street lights in some California cities. These include San Jose, Campbell (side streets only), Redwood City, East Palo Alto, Atherton, unincorporated areas in San Mateo County, and Santa Maria in Northern/Central California. In Southern California cities include San Diego and some of its suburbs near the observatory. There are some in Compton near LA. Long Beach was almost 100% lit in LPS but they were nearly all replaced by HPS in the late 90s. There are also LPS streetlights in a number of Arizona cities near observatories such as Flagstaff, Glendale Safford, etc. I like LPS as an interesting lamp, especially the neon part during warm up, but they're so weird on the roads because of their deep monochromatic light. Hard to see the sidewalks!


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## EricB (Jan 1, 2008)

I discovered it was not just the one town of Massapequa Park, but rather the entire township of Oyster Bay (Basically, all of eastern Nassau Co. stretching from the LI Sound to the ocean). Also, neighboring Babylon township has them also. In fact; theirs were even fit into the standard street lamp fixture! LPS's usually are longer, requiring special long fixtures. I guess they found a way to make a smaller bulb.


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## Silverliner25s (Jan 1, 2008)

The 18w and 35w LPS lamps are small enough to fit inside cobraheads (the standard street light fixtures). There are Westinghouse OV-15 Silverliner street lights in Wisconsin with 35w LPS lamps. Weird for sure!


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## yuandrew (Jan 3, 2008)

The parking lot of Diamond Ranch High School close to where I live is entirely lit with Low Pressure Sodium lamps although the street leading up to the campus and the surrounding neighborhoods are all lit with HPS. 

Look at the color of the tree leaves.










> LPS's usually are longer, requiring special long fixtures. I guess they found a way to make a smaller bulb.



Funny, you reminded me of a *dream* I had once where I was behind a Taco Bell or KFC and right next to the back door was an LPS bulb with the inner tube twisted into a spiral (similar to a compact fluorescent lamp but narrower and longer.) I dreamed in color accurately enough to tell the difference between that "strange" low pressure sodium lamp and the high pressure sodium lamps in the streets.


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## LED-FX (Jan 4, 2008)

Most of UK is still on SOX, much prefer SON which is getting phased in.

SOX popular with astronomers because the near monochromatic , its only 2 emission lines close together, mean its easy to make a dichro filter to take it out.

Couple links mebbe of interest;

http://www.lamptech.co.uk

http://members.misty.com/don/

http://ioannis.virtualcomposer2000.com/spectroscope/index.html

Cheers

Adam


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## hank (Jan 4, 2008)

Yep. It's amazing to me how few people today have ever seen the Milky Way in the night sky. It used to be glorious.


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