- 65 deg lighting

[Davebones]

We have a test chamber that goes to - 65 degrees . Can someone give us a idea of 4' fluorescent lights that can handle this temperature ...

 

[sgunsel]

This sounds like a good application for incandescent lighting. Most fluorescents have trouble lighting up at +32F.

 

[bpk]

They say LED's are very versatile in cold weather, maybe an option, they make an LED replacement for a 4' flourescent tube that uses the same pins but its expensive.

 

[sgunsel]

Most of the LED fixtures/lamps that I see will never be economical replacements for any other lighting. Especially in places like this chamber, unless they are totally irreplaceable once installed and the fixture will be replaced when the lamps fail. That might justify LEDs.

 

[Electric-Light]

How much output do you need? You maybe able to use LED strips designed for supermarket display cases. They use an electronic driver and operate at low voltage (12-48v usually) In the past, HO fluorescent lamps were used inside a sleeve to stay warm enough. LEDs are quickly replacing fluorescent for this particular application.

-20F is about the limit for fluorescent. Once you get it started, you can use insulating tube covers and tight fitting fixtures to let it warm, but it may not start below -20F.

 

[broadgage]

LED is the way to go for very low temperatures.
Several suppliers sell LED trubes intended to be used instead of flourescent lamps, I can not recomend these for general lighting of offices etc, due to the high cost and often reduced light output.
For very low temperatures they should be ideal.
If however the test chamber can also be warmed to above room temperature, then LEDs might be less suitable.

Another posible alternative would be sealed beam lamps as used for vehicle headlights. These survive fine in antarctic temperatures and can be powered from line voltage via a suitable transformer.
They also survive well at high temperatures, if this test chamber is used thus.

Regular incandescent lamps work fine at low temperatures provided that they are protected from contact with water or ice, or strong draughts.

 

[Electric-Light]

LED is the way to go for very low temperatures.
Several suppliers sell LED trubes intended to be used instead of flourescent lamps

Those tend to suck. They're usually sold by someone trying to pull a quick one on you by telling its more efficient than fluorescent.

The ones made for see-thru freezers are UL rated for such application where condensation is expected. They're not supposed to be operated at room temperature though. Additional heat stress will reduce their life dramatically.

I was under the impression that they're more efficient than fluorescent, but apparently not. I'm surprised that a LRC research found otherwise.

http://www.lrc.rpi.edu/programs/solidstate/cr_freezers.asp

I don't recommend LEDs for just about everything, but a few exceptions are very low wattage DC powered applications and extreme cold operation.

You can consider a dichroic halogen lamp through a window. The dichroic reflector only reflects a small amount of IR, so the heat entering the chamber can be minimized.

 

[BullsnPyrs]

LED is probably the way to go but picking the product might be difficult. Cooler door fixtures I have worked with have been designed to throw light to the side to illuminate product. They work great in their designed application but might be a poor choice for general illumination.

 

[rt66electric]

300 watt jelly jar

300 watt jelly jar

Whats wrong with the good-ole weather-proof jelly jar with a cage??

 

[Electric-Light]

Whats wrong with the good-ole weather-proof jelly jar with a cage??

300W? Ultra-low freezers do not have that much BTU capacity and the coeff. of performance at -65 is something like 0.25 to 0.5, that's if the cooling system can even keep up with 300W thermal load.