Previous in Forum: Minumum Earthing Resistance Value   Next in Forum: DSDR
Close
Close
Close
14 comments
Rate Comments: Nested
Anonymous Poster

Flourescent Lighting Question

01/08/2011 8:43 AM

Why can't Flourescent tubes be made in a wide flat shape rather than a tube shape?

Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Guru
Engineering Fields - Optical Engineering - Member Engineering Fields - Engineering Physics - Member Engineering Fields - Systems Engineering - Member

Join Date: Apr 2010
Location: Trantor
Posts: 5363
Good Answers: 647
#1

Re: Flourescent lighting question

01/08/2011 9:04 AM

Who says they can't be? A number of companies have developed wide, flat fluorescent lamps -- with varying degrees of success. Some of the early developers have gone out of business since flat fluorescent lamps have problems with capacitance, electrostatic attraction, cathode sealing, non-uniformities and glow 'beading' in the glowing gas, to name a few issues. Here's an example of some small flat lamps that were made about 15 years ago:

http://statusreports.atp.nist.gov/reports/93-01-0109.htm

These days you can make a flat lamp using LEDs (either as an array of LEDs or by using a few LEDs with a flat light guide) and get more lumens per watt without the need of a high voltage ballast.

__________________
Whiskey, women -- and astrophysics. Because sometimes a problem can't be solved with just whiskey and women.
Reply Score 1 for Good Answer
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#2
In reply to #1

Re: Flourescent lighting question

01/08/2011 9:47 AM

I sure wish they would put more effort into LED's. These compact flourescents don't last anywhere near as long as advertised. I lit up my basement with them, (about 10 or 12), half are dead in less than a year, and I don't go down there very often.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Reply
Guru
Engineering Fields - Electrical Engineering - Analog and Digital Circuit Design Engineering Fields - Electromechanical Engineering - Transformers, Motors & Drives, EM Launchers Engineering Fields - Engineering Physics - Applied Electrical, Optical, and Mechanical

Join Date: Jan 2008
Location: NY
Posts: 1207
Good Answers: 119
#3
In reply to #2

Re: Flourescent lighting question

01/08/2011 2:58 PM

How often do you turn them ON/OFF? I use CFL's almost everywhere and the ON/OFF life does NOT meet package specs. However, the ones I leave ON 24/7/365 do last an average of 14 months (>10000 hour spec). That's not a subjective measurement. I actually write the "installed date" on all my CFL bulbs.

Failed CFL's are usually found within 12-24 hours because of the "BURNT" odor that permeates the house when they expire. While annoying, I'm not concerned about the burnt failure mode and fully expect the industry will eventually reduce/eliminate this occurrence.

Reply Off Topic (Score 5)
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#4
In reply to #3

Re: Fluorescent lighting question

01/08/2011 3:06 PM

Less than once a day. I think it is the on/off cycling that causes them to fail. At my failure rate I think my overall cost, at this point is more than incandescents would cost.

I also think that turning them off before they have completely warmed up plays a role, but not sure.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Reply Off Topic (Score 5)
Guru
Engineering Fields - Electrical Engineering - Analog and Digital Circuit Design Engineering Fields - Electromechanical Engineering - Transformers, Motors & Drives, EM Launchers Engineering Fields - Engineering Physics - Applied Electrical, Optical, and Mechanical

Join Date: Jan 2008
Location: NY
Posts: 1207
Good Answers: 119
#5
In reply to #4

Re: Fluorescent lighting question

01/08/2011 3:29 PM

Agreed. Thermal cycling stress on the cheap electronic components seems to be the main failure mechanism. Voltage transients and/or current surges could also be a factor.

I still have a few locations which need incandescent bulbs. Most CFL designs are not yet ready for frequent ON/OFF locations and some outdoor fixtures (too cold!).

Reply Off Topic (Score 5)
Guru
Popular Science - Weaponology - bwire Hobbies - Car Customizing - New Member

Join Date: Dec 2007
Location: Upper Mid-west USA
Posts: 7498
Good Answers: 97
#6
In reply to #2

Re: Flourescent lighting question

01/08/2011 5:13 PM

They're very suseptible to voltage fluctuation, this is your sign to protect your sensitive equipment.

__________________
If death came with a warning there would be a whole lot less of it.
Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#10
In reply to #6

Re: Flourescent lighting question

01/09/2011 10:05 AM

The compact fluorescents are the only thing I've ever had a problem with. I do have a surge protector on the computer.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Reply
Guru
Hobbies - RC Aircraft - New Member

Join Date: Aug 2007
Posts: 901
Good Answers: 9
#8
In reply to #2

Re: Flourescent lighting question

01/09/2011 9:50 AM

And outside in the winter, or any un heated area for that matter they are useless!

Reply
Guru
Hobbies - Fishing - New Member

Join Date: Jun 2008
Location: Raleigh, NC USA
Posts: 13529
Good Answers: 468
#11
In reply to #8

Re: Flourescent lighting question

01/09/2011 10:15 AM

That may be part of the problem. The basement is unheated, although it doesn't get below, probably mid 40's. It does take them a while to reach full brightness.

Banning incandescents has already begun, which really pisses me off. If they are going to force us to use cfls, they should work as advertised. I'll never understand the utter stupidity that runs through the local, state and federal government.

I've got 5 burned out cfls in the basement right now. Of course they contain toxic material, unlike incandescents.

__________________
Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety. Ben Franklin
Reply
Guru

Join Date: Apr 2006
Location: Cincinnati, Ohio, USA
Posts: 662
Good Answers: 49
#7
In reply to #1

Re: Flourescent lighting question

01/08/2011 11:41 PM

One of the biggest issues is installing and/or changing the lamps- ALL fixtures have been designed with clearance for round lamps 1.5 inches or smaller in diameter.

IF a lamp that is only 1.5 inches wide were used- should not be a problem but it is a challenge to get adequate lumen output from just the "flat" side to match the equivalent circular shape, with its inherent larger surface area.

__________________
NO MATTER HOW WELL YOU HAVE DONE SO FAR, ALWAYS TRY TO BE BETTER TOMORROW.
Reply
Guru

Join Date: Dec 2010
Location: North West England
Posts: 1170
Good Answers: 153
#9

Re: Flourescent Lighting Question

01/09/2011 9:56 AM

You would not gain anything by making the tubes wide and flat. Fluorescent tubes emit light equally in all directions so half the light would be emitted towards the fitting. If you study catalogues of when they were first introduced, almost all the fittings had the axis of the tube sited at the focus of a rolled metal white enamelled parabolic reflector, so that the light was directed to where it was needed. In later models this feature was dropped. A case of aesthetics winning out over efficiency. The reflectors used to attract electrostatic dust and I can remember when lamp cleaning throughout a factory was a routine maintenance task.

Fluorescent tubes generally replaced incandescent light bulbs, and in their time were a breakthrough in high efficiency, high intensity lighting. A tube uses less glass than a rectangular section, it is stronger so that you can use thinner glass, and it is easier to extrude and seal. This makes manufacturing much simpler and cheaper. Usbport has listed some of the technical problems associated with non-tubular so I won't repeat, but several factors associated with how they are handled during manufacture also make a tubular lamp preferable.

LEDS emit a 160° cone of light so don't lose any light towards the fitting. This makes them much more suitable for large flat lighting, but I think that in the next few years improvements in organic photo-diode technology will allow illuminating panels to be printed onto walls and other flat surfaces. The small amount of mercury in tubes is already causing concern over their waste disposal and this will hasten the demise of the fluorescent tube.

Reply
Commentator

Join Date: Dec 2010
Posts: 89
Good Answers: 1
#12

Re: Fluorescent Lighting Question

01/09/2011 3:57 PM

actually fluorescent lights do not emit light equally in all directions, a circle or sphere or circular tube emits light equally, because the sides or outer surfaces are equal distance from the centre.

Nothing spectacular about this knowledge, a flat tube will emit more light at the curvature or ends/sides than the flat surface as there is more surface area in that confined space of the curve EG: a one inch edge curve one inch apart from each flat surface is three and a half inches of surface in one inch of the tube, so the edges would glow far brighter than the balance of the tube, though this is not the reason they do not make them that way - total light being the value point regardless of how silly it looks.

the reason is the same as all mechanics, a sphere or a tube absorbs impact at far greater ranges than a flat surfaced object, tubes and spheres are stronger, you would need tougher glass and the cost would increase too much against current costs. Have no fear a previous answer is indeed correct Fluros days are numbered, they are antiquated and bad for you eyes to boot.

Reply
Guru

Join Date: Jul 2006
Location: Eastern Kansas USA
Posts: 1503
Good Answers: 128
#13
In reply to #12

Re: Fluorescent Lighting Question

01/10/2011 1:07 AM

Enerventure,

Are you sure? The visible light from a fluorescent tube is from the phosphor chemical coating on the inside surface of the bulb. This coating must absorb the UV radiation from the low-pressure mercury vapor arc inside the tube. Therefore light output is directly dependent on the amount of UV light absorbed. Getting a uniform arc across a flat area is more difficult than within a tube. Buried in my statement above and hinted at in your comment is the real reason why fluorescent tubes are not flat. The low-pressure is a fairly high vacuum. Spherical and tubular glass bulb shapes are much stronger than flat shapes--the flat ones would have the two parallel sides pulled together, or would break fairly easily, or would need much thicker (and heavier) walls.

--JMM

Reply
Power-User

Join Date: Apr 2007
Location: New york
Posts: 139
Good Answers: 6
#14

Re: Flourescent Lighting Question

01/10/2011 7:52 PM

Just chiming in here: Why does it matter ?

Although my opinion is only that, I couldn't care less about CFL's, and fluorescent lighting is something that should be phased out ASAP.

For all those on the CFL bandwagon, get off. The world is being pushed into an era of "green this" and "green that", all about the environment and your "carbon footprint".

Anyone care to postulate on what the SHORT-long term effects of filling every landfill with fluorescent lightbulbs ?

I am in NYC, some states are more lenient than others, but you basically need a hazmat team to clean up a fluorescent bulb mess. You must be careful, and if it gets in your rug be more careful. I also do NOT suggest vacuuming up any of it. You would effectively be taking any residual mercury vapor and dispersing it in the air.

I agree with some of these posts about CFL life because in my experience I have had to replace almost as many as any incandescent bulbs I have ever had. One issue for me about fluorescents is that a bulb is as reliable as the fixture, and I have some ancient Fluorescent fixtures that even with heavy use have very long bulb life. Of course these fixtures are VERY old, and all the new ones I have bought in the past ten or so years go through bulbs all the time.

What all people must do, is start using LED lighting systems, they are non toxic to the environment, and they give you the lowest in power consumption, which IS the goal here.

__________________
In such a vast universe, I can only bask in my own insignificance....
Reply
Reply to Forum Thread 14 comments

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

bwire (1); csoulpro (1); energygod (1); jhhassociates (1); jmueller (1); kramarat (4); Life is Enerventure (1); mjb1962853 (2); NSS (1); Usbport (1)

Previous in Forum: Minumum Earthing Resistance Value   Next in Forum: DSDR

Advertisement