Power Groove fluorescent tubes

[Yoshi]

Hi,

Does anybody know anything about the GE fluorescent tubes made in the 1960's that were called "GE Power Groove" tubes? I have been trying to find one ever since I started collecting lightbulbs. I remember that when I was a kid, I went to an old museum that had lots of these tubes, but this same museum has been remodeled and now it has none! I even spoke with the owners of the building and they knew nothing about them; It was too late.

Here's a 1963 ad that shows a Power Groove tube:

[Ross]

Hi Yoshi, wow, what a strange thing !  I have not seen one of those before.  I can just read the text on the advert; the claim seems to be that the "grooves" allow a 9 foot arc to be fitted in to an 8 foot tube.  Am I correct in thinking that these longer tubes are only really of use in 220/240 Volt areas ?  8 foot tubes are still used here in the UK, as are pairs of 4 foot tubes in series with the same ballast.

[Mónico González]

Hi everybody!

I used to see these tubes here in a general store at my town 15-20 years ago.
They did use about 500 of these tubes for lighting the whole sales room (about 3000 sq. meters surface). I also have seen them sometimes at Metropolitan Subway (Metro) of Madrid.
These tubes did not very common for general purpose here in Spain because its extreme lenght, but they was moderately used for business lighting.
As you have said, the high lenght of these lamps implies a moderately high voltage supply to start and keep the arc running.
Here in Spain there is no problem for powering them because we have a 220-230/380-400 volts supply system, so the easier limiting system for them can be a simple series mounted inductive coil ballast. But don't forget that these tubes were designed in US, where the voltage (120 volts) are lower than in Europe. Such voltages are not a problem if the ballast are constituted by a limited current step-up self-transformer.

The main purpose to mould these enigmatic holes onto the glass wall was primarily intended to obtain an assymetrical axial light distribution around the tube, giving two maximum light lobes emerging each one from opposite sides of the tube. So, the light distribution around the tube on a plane that were perpendicular to the axis, are noticeably "eight" shaped.

About the obsolete tubes from the store I did mention above, really I ignore were went these tubes to when the lighting system of the sales room was updated some years ago. I would like to get some ones, but regrettably I didn't get none of them!

Best regards,
M. Gonz?lez

P.S. My website is online again! http://mis-bombillas.webcindario.com


[This message has been edited by M?nico Gonz?lez (edited January 13, 2004).]

[Alan Franzman]

I have seen some of those somewhere before, can't remember where... It must be a place which bought a large stock of them and still has spares.

I think it's a disgrace that a *museum* would lose track of its own vintage fixtures and lamps during a renovation.  What kind of museum is it?

BTW, 8-foot lamps are indeed used here in the U.S.A. on both 120 volt (residential/universal) as well as commercial and industrial 277 volt lighting circuits.  Older fixtures used step-up transformer ballasts, and now electronic ballasts are also available.

------------------
 
Alan "A.J." Franzman

Email: a.j.franzman at verizon dot net

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[Yoshi]

Hi,

I do not know much of these tubes, other than what is written in the ad I posted... My country's voltage is 125-130v, so these tubes may have not been for 220v, who knows?

I would buy these tubes if I found them on eBay or locally, working or not, although working ones are much more preferable of course.

The "museum" I mentioned was some sort of general purpose building, which at the time was a museum. It has become many different things throughout the years, I think it is now a furniture store or something. I don't know when the renovation took place but it may have been many years ago, maybe 6 years. The first and only time I saw the tubes, many of them were dud or about to become dud.

Straight 8 foot tubes are a very normal thing to me, but not these with "power grooves".

By the way, there is a similar fluorescent tube called the "Power-twist", which was made by Duro-Test. I believe these have been discontinued too. (Picture provided by SilverLiner):

[Ed Covington]

The POWERGROOVE fluorescent lamp first appeared in 1956. It was developed by Eugene Lemmers and John Aicher at Nela Park, the lighting headquarters of GE, in E. Cleveland, Ohio.

[Max]

Hi All,

     

quote:Originally posted by M?nico Gonz?lez:

The main purpose to mould these enigmatic holes onto the glass wall was primarily intended to obtain an assymetrical axial light distribution around the tube, giving two maximum light lobes emerging each one from opposite sides of the tube. So, the light distribution around the tube on a plane that were perpendicular to the axis, are noticeably "eight" shaped.

This is not what I have read on this particular subject, and what would be the benefit of a general lighting lamp with such emission pattern beside a slightly better light control in specially designed optics?

By the 1950's, companies such as GE or Sylvania wanted to make high-power (>80W) fluorescent tubes for large area lighting. The problem to solve was that increasing the power loading of standard F lamps (T12/Argon-mercury filling) had the effect of severely decreasing their efficacy.. so was lost in the process most of the benefits originally attributed to those kind of lamps.
The reasons for this phenomenon are two-fold. First, increasing the lamp power loading increases its cold-spot temperature. So does the partial pressure of mercury in the discharge, which make the medium prone to reabsorbing its own resonance radiation.
The second reason is that increasing the lamp current results in an increased electron density while the electron energy remains quite the same. This leads to an emission of mercury resonant radiation (185 & 254nm) that saturates above a certain dissipated power, which was below the target of these companies at this time.
 
So the solutions to both problems lied in finding a way of keeping the lamp cold-spot around 40C for optimum mercury partial pressure, and an other way of increasing the discharge electron temperature. There were many approaches that depended on the manufacturers ...

GE: found that increasing the surface contact of the mercury-argon discharge with the bulb would increase the electron temperature. Since the tube diameter could not be too large (it would decrease the lamp efficacy due to mercury resonance reabsorption), GE chose to use non-circular cross section tubing, such as already used for LPS lamps.
Crescent-shaped tubes were chosen because they were the least expensive of most designs. It had also the benefit of increasing the discharge path-length for a given lamp dimension, hence the "9 feet of light in a 8 foot lamp" motto. However, this had the inconvenience of increasing the striking voltage of the lamp.
As for the cold spot, the extremities of the crescent cross-section were devoid of plasma (discharge) and were the lamp cold spots.

Sylvania: preferred to choose a different approach as Corning was their supplier of glass tubing. Sylvania did not want to finance Corning's development of non-circular cross section tubing, primarily because of the high cost of these tubes compared to standard tubing, and also because it would pave the way for Corning to sell these kind of tubes to competitors.
So, the solution of Sylvania was to employ a neon-mercury filling instead of the standard argon-mercury mixture. This is the change of buffer gas which led to an increased electron temperature.
This way, they still could commercialise straight HO and VHO lamps. The cold-spot problem was solved with the use of longer electrode stems fitted with thermal shields (metal disks), which shield each lamp extremities from the heat from the discharge.
Anyway, Sylvania offered also crescent-moulded lamps on the market as to offer a "equivalent" of GE's product.

Philips: used almost the same approach as Sylvania's at the exception of the cold-spot. Philips solved this latter problem either with a single dimple in the middle of the lamp, or by fitting a heat sink on the lamp, usually a metal rod affixed to the lamp and the fixture via a spring.

This problem of cold-spot is also recurrent in today's T5 lamps and compact fluorescent. In both case the solution is either the use of mercuyr-indium amalgam (introduced by Osram in 1961), longer stem length, or bulb appendices away from the plasma (like in Philips PL lamps).
 
Worth of mention, is that an alternative way of increasing the electron temperature was found in approximately the same time HO and VHO lamps were developped. The use of standard lamps filled with glass wool (called "recombination structure" because ions and electrons recombine there) increases tremendously the surface contact between the discharge and a "wall". As you might guess, this solution was never put on the market due to manufacturing problems.

Best regards

Max

[This message has been edited by Max (edited January 14, 2004).]

[Stan]

Max is right with "cold spot", but is one reason again. Optimal dimensions for greatest luminous flux is, if the tube is "obling cross-section" 1:3. But it is very difficult technologicaly and the air pressure around is very inequaly, was selected this cross-section. Power Groove was made also for much more lower wattage than 215 watts. Many years ago I saw a sample of POWER GROOVE with EXTERNAL phosphor (red lighting organic composition eosine or fuchsine- the base of red inks!), giving deluxe slight pink color of light.
Stan

[Max]

Hi Stan!

That's right that a elliptical cross section is simpler than the crescent design, but the force exerted by air along the shorter axis would have prompted for a thick-walled lamps. Actually I find that Power-groove lamps have much thicker walls than T18 tubes used in VHO lamps from other manufacturers.
I also believe there is two other problems which prevented the use of the elliptical design:
-1: its strong heterogeneous light distribution, which would require dedicated optics
-2: a reduced bulb strength which I think would break easily under its own weight if held by only one of its extremities.

quote:Originally posted by Stan:

Many years ago I saw a sample of POWER GROOVE with EXTERNAL phosphor (red lighting organic composition eosine or fuchsine- the base of red inks!), giving deluxe slight pink color of light.

Are you certain it was a fluorescent coating and not just an external coat intended to filter the light generated by the fluorescent layer inside the lamp?
If it was really an external fluorescent coat, it had to stick very well on the lamps, otherwise we would experience a recrudescence of skin cancer LOL


Regards.

Max

[Stan]

It was really thin layer of phosphor. I don?t remember, that it was perhaps 30years ago, if it was (e.g.) gelatine layer or so. I know only, that it was originaly from GE, received in inland work Tesla from USA. The sample was losted, never from formerly workers are not able remind it. Moreover if I ment air pressure, I ment difficulties of right-angle cross section. One sample of POWER-GROOVE (broken, part around electrodes and about half meter of tube) in my collection has the wall lucidly more thick than usual fluorescent lamp tube! Stan

[Max]

quote:Originally posted by Stan:

One sample of POWER-GROOVE (broken, part around electrodes and about half meter of tube) in my collection has the wall lucidly more thick than usual fluorescent lamp tube! Stan

Since you have a broken Power-Groove lamp at hand, can you tell me how the electrodes are constructed? Do they present two parallel probes each spot-welded to each support of the filament? and does the stem have any metal disk attached to its neck?

Max



[This message has been edited by Max (edited January 14, 2004).]

[James]

I don't think I can add much more to your excellent introduction Max!  Electrode construction is similar to a normal HO/VHO lamp with a longish stem and anode wires, since these are rather high current tubes.  Also in the case of 96" tubes, to produce a cold spot one of the indents is not formed, I think it is the third indent in from one end but can't remember without looking at the lamp.  I don't think this was necessary on the shorter 72" and 48" tubes which ran at a lower current.

Incidentally as far as I know PowerGroove tubes are still available today.  It is in GEs most recent catalogue I have and I bought a number of them about five years ago to sell on to a customer who was having trouble finding them.  All three lengths were still available then.

DuroTest also made an interesting design, it was no greater in arc length but the tube has a much greater surface area and generates more lumens on account of the fact that the phosphor area is larger, and the UV radiation has less distance to travel through the discharge before hitting the phosphor.  Its called the Power-Twist and is made from standard T17 glass tubing with a spiral indented into it all along its length.  Although the new DuroTest in USA still sells them, I think its now being made by GE in Nagykaniza under license of the Japanese firm Marutoki - www.marutoki.com   They also do a must unusual range of high efficacy T12 spiral-twist tubes designed to replace regular T8 versions!

James.

[Yoshi]

Hey, look what I found:


 http://catalog.gelig hting.com/cgi-bin/gx.cgi/AppLogic+FTContentServer?&pagename=GE_Lighting/Catalog/Production_www/home&mode=browse&path=,FLU&subcat=L2-43



[This message has been edited by Yoshi (edited January 15, 2004).]

[Max]

Thanks for your addition James. I am a bit confused for the probed anodes. John Waymouth (Sylvania) reportedly invented this electrode design, so I assume that by the time GE introduced Power-Groove lamps these probes were patented by Sylvania. I just wondered what solution GE chose (at this time) for its high-current electrodes.
Since Sylvania later offered Power-Groove lamps, perhaps they made a cross licence between bulb design and electrode configuration.

Regards

Max

[Max]

quote:Originally posted by Max:

Philips: used almost the same approach as Sylvania's

Interestingly I just read that it was not the case. Philips found that replacing the argon buffer by Neon had the effect of increasing the sputtering/evaporation rate of the cathodes (at the cost of the lamp life).
Philips preffered to keep argon as a buffer, but increased its partial pressure as to raise the electric field in the positive column and decrease the electrode evaporation rate (increased by the higher lamp current.)

Max