jonsnow399
Well-Known Member
A guy on Youtube makes a homemade ac hood that directly cools the bulb and claims it has no bad effects. Does anybody know the opposite for a fact and have any manufacturers links or real evidence to prove otherwise?
Can DE bulbs be directly air cooled?
- Thread starter jonsnow399
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upsetter.
Active Member
While SE bulbs are under vacuum, DE bulbs are full of nitrogen gas. The nitrogen atmosphere allows the bulb to operate at a higher temperature, which increases its efficiency. The downside of a gas-filled bulb is that the gas conducts heat from the outside of the bulb to the arc tube. Any air blowing directly on the bulb induces a temperature change in the arc tube, causing a loss in efficiency. Therefore, DE bulbs do not tolerate air blowing directly on them like in active cooling setups (aka “cool tubes” in which the SE bulb sits inside of a tube with a fan housed in the luminaire or lamp hood).
- high times. Everything I have read seems to line up with this. The ACDE hood indirectly air cools the bulb which is supposed to be okay.
- high times. Everything I have read seems to line up with this. The ACDE hood indirectly air cools the bulb which is supposed to be okay.
jonsnow399
Well-Known Member
Thanks for replying, I understand the theory behind this but this guy claims there are no significant bad effects, the loss of efficiency is all the claims i have seen.
CobKits
Well-Known Member
does he claim it? or does he measure it?
jonsnow399
Well-Known Member
he's only making claims as far as I know. I think he means that it can be done without blowing the lamp up. lol Has anyone tried it and measured the efficiency loss? Does it shorten the life of the bulb? Someone should test this, Cobby, how about you?
upsetter.
Active Member
Well yeah... That is the only drawback I am aware of. How much efficiency is lost? I don't know, but that seems to be a good enough reason not to do it. It's improved efficiency is the main reason to use it.
CobKits
Well-Known Member
I have some acdes but not all that interested in hps testing tbh. i cant keep up with led testing
pretty sure somebody on youtube simulated this a few years ago by varying air velocity
jonsnow399
Well-Known Member
As far as I know it was a guy testing an ac/de reflector that doesn't cool the bulb directly, it didn't have an effect. Yeh, it would be hard to test since there are very few directly cooled reflectors that i have seen.
upsetter.
Active Member
Before I switched to LED, i was ready to buy a bunch of those boss reflectors. They look great.
ttystikk
Well-Known Member
You get loss of efficiency and degraded spectrum output. Is he bragging about getting a pound under his 1150DE?
jonsnow399
Well-Known Member
nah, as I read further he says he is going to get a ac/de reflector later, If his jerry-rigged reflector is so good, why would he buy a AC/DE?
jonsnow399
Well-Known Member
On a different note, I am thinking about getting a AC/De reflector with a 1000 watt bulb to run this winter. I want to switch to a 315 cmh bulb for summer, is the footprint all wrong for that?
CobKits
Well-Known Member
reflectors are entirely different
jonsnow399
Well-Known Member
I have a de cmh 315 watt bulb and a ballast to hook to the reflector, so it will work but i was just trying to figure the footprint.
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jonsnow399
Well-Known Member
I thought all de sockets were the same, regardless of bulb,
CobKits
Well-Known Member
ive never seen a DE CMH, sorry