dor123
Member
Offline
Gender: 
View
Posts
View Gallery
Other loves are printers/scanners/copiers, A/Cs
|
I have noted that unlike most brands of long T5 lamps (Those that have krypton buffer, and not a pure argon like the miniature T5s and are called HO and HE) which have electrodes length similar to that of the T8 and the T12 lamps, in Osram long T5 lamps, the electrodes length is far more long, so the electrodes filaments are far away from the ends of the lamps, resulting in a larger dark area and end blackening on Osram long T5s. You can see this in my picture here. Why Osram long T5s are different such? (Sylvania, Philips, Eurolux and other brands, haven't so long electrodes) |
|
|
« Last Edit: January 28, 2011, 09:49:18 AM by dor123 »
|
Logged
|
I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
|
Medved
Member
Offline
Gender:
View
Posts
View Gallery
|
| Possible reason: They may need lower temperature for the cold spot, in order to operate at correct mercury pressure...
|
|
|
|
Logged
|
No more selfballasted c***
|
DieselNut
Member
Online
Gender:
View
Posts
View Gallery
John
  
|
Possible reason: They may need lower temperature for the cold spot, in order to operate at correct mercury pressure...
medved, is this the same reason for the T12 VHO (215 watt T12 8 foot lamp) in USA? |
|
|
|
Logged
|
Preheat Fluorescents forever!
I love diesel engines, rural/farm life and vintage lighting!
|
Medved
Member
Offline
Gender:
View
Posts
View Gallery
|
Possible reason: They may need lower temperature for the cold spot, in order to operate at correct mercury pressure...
medved, is this the same reason for the T12 VHO (215 watt T12 8 foot lamp) in USA?
It may well be, but it is only my guess... It may be, then only Philips make short ends, as they hold some key patents for hot operating amalgam (i think or James or Colin mentioned it in the context of some magnetic CFL, what should be removed from the market due to some patent issues) and Osram does not want to pay royalties... |
|
|
|
Logged
|
No more selfballasted c***
|
James
Member
Offline
Gender:
View
Posts
View Gallery
|
| Have you checked both ends of the tubes? In the Sylvania production we have a long mount at one end of the tube and short at the other end. I don't have an Osram tube to hand to check now, but thought they were also the same. At least the ones which are made in Germany are the same because those are made by SLI, genuine Osram T5's are made in Italy. In case T5 tubes are operated vertically, they should be orientated correctly to attain the correct Hg vapour pressure and optimal efficacy.
|
|
|
« Last Edit: February 04, 2011, 04:14:38 PM by James »
|
Logged
|
|
Zelandeth
Member
Offline
Gender:
View
Posts
View Gallery
    
|
| That's quite interesting - only after seeing this post that I actually looked at this in more detail. Sure enough, some of the lights in our local Tesco have a far longer "dark space" at one end of the tube than the other. Seems to be more widespread than I'd have thought before.
My guess for the reason for this would be cold-spot temperature control.
|
|
|
|
Logged
|
|
Luminaire
Member
Offline
View
Posts
View Gallery
|
| Don't some of them use axially positioned cathodes to make it fit within the narrower T5 tube, thus longer cathode overall?
|
|
|
|
Logged
|
|
dor123
Member
Offline
Gender:
View
Posts
View Gallery
Other loves are printers/scanners/copiers, A/Cs
|
| I think all of the major brands of non-miniature T5s have one electrode longer then the other.
However the average length of both electrodes is similar to T8s/T12s/miniature T5s (Sylvania/SLI T5s is build such).
The low cost chinese long T5s have essentially the same electrodes as the T8 and the T12.
Osram on the other hand, have much longer electrodes then the others.
Both of the electrodes have the same length, but one of them have a fence in front of it, reduceing the end blackening length in this area and heating this zone, so the cold spot is on the other electrode.
I used laser shading to check the electrodes of the Osram 21W HE T5 in the storage of Carmel hospital.
|
|
|
|
Logged
|
I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
|
James
Member
Offline
Gender:
View
Posts
View Gallery
|
I think what you are maybe seeing in the Osram lamps is the mercury dispenser and getter, which is shaped like a small house roof and positioned just ahead of one electrode. This is a development of SAES getters of Italy. You can see further details on their zebsite at http://www.saesgetters.com/default.aspx?idPage=1048 |
|
|
|
Logged
|
|
dor123
Member
Offline
Gender:
View
Posts
View Gallery
Other loves are printers/scanners/copiers, A/Cs
|
| I brought an Osram FH 21W/840 HE T5 (Not installed yet, the OEM lamp still works), and did a laser shading.
One electrode is longer then the other and both have longer supports, and i also saw the mercury dispenser and getter ahead of the shorter electrodes.
The lamp itself btw, was made in Germany and not in Italy, like most Osram fluorescent lamps.
Interestingly, Sylvania (SLI) newer Luxline Plus T5s also have very long electrodes now.
|
|
|
|
Logged
|
I"m don't speak English well, and rely on online translating to write in this site.
Please forgive me if my choice of my words looks like offensive, while that isn't my intention.
I only working with the international date format (dd.mm.yyyy).
I lives in Israel, which is a 220-240V, 50hz country.
|
