[ChrisP]

This is probably a very stupid question, but does it make a difference which way you put an HQI DE bulb into the socket - i.e. with the little glass "nub"(the point where the bulb connects to the outer glass) facing in (toward the reflector) or out (toward the tank)?
Chris

[charlie]

Sorry Chris, I have only used mogul bulbs throughout my career. I am sure that someone here can help!!! Sorry

[Ninong]

Originally Posted by ChrisP

This is probably a very stupid question, but does it make a difference which way you put an HQI DE bulb into the socket - i.e. with the little glass "nub"(the point where the bulb connects to the outer glass) facing in (toward the reflector) or out (toward the tank)?
Chris

Yes, it does make a difference. Remember this: missionary position, nipples up. That means pointed towards the reflector, not pointed downwards towards the water.

Your question assumes that it's even possible to put it in either way. Have you tried?

It's also acceptable to have the nipple pointed sideways, assuming it's possible to insert it in the socket that way. Just not down.

[charlie]

Thanx Ninong, you learn something new everyday.

[Ninong]

"The lamp should be used only in appropriate fixtures, which should be equipped with protective glass cover. Fingerprints should be wiped off with a clean cloth soaked with alcohol to prevent their penetrating into the quartz glass. Double-ended lamps must not be operated with internal exhaust tip in downward position." -- Ushio/BLV

Read this post from six years ago.

[ChrisP]

Thanks, Ninong! I'll never forget your "missionary position" analogy! Actually, my Viper fixture allows me to put bulbs in either way.
Chris

[Ninong]

Originally Posted by ChrisP

Thanks, Ninong! I'll never forget your "missionary position" analogy! Actually, my Viper fixture allows me to put bulbs in either way.
Chris

OK, but I hope you read the part in my post where I say that it's only the inner nipples that matter. Also, there may be a difference between 150w and 250w lamps. My 250w lamps (both Ushio/BLV and AB) could only be inserted in the sockets in the correct orientation.

Here's a link to that entire thread from February 2002. Unfortunately many of the photos seem to have been lost in one of the many software upgrades.

[Ninong]

The reason for the rule is this: halide salts will settle in the tiny depression causing it to blacken and overheat, thus shortening the life of the lamp.

[Ninong]

Originally Posted by charlie

Thanx Ninong, you learn something new everyday.

Yes, some people do. Richard Harker wrote an entire article, "Nipple Nonsense," in which he disputed this rule. He even came back months later with another article, "Nipple Nonsense Revisited," in which he tried to back up his absurd position based on his own independent experimentation. Whatever. I can't believe he was actually paid American money for either article.

Here is the warning Ushio/BLV prints on the packaging:

"The lamp should be used only in appropriate fixtures, which should be equipped with protective glass cover. Fingerprints should be wiped off with a clean cloth soaked with alcohol to prevent their penetrating into the quartz glass. Double-ended lamps must not be operated with internal exhaust tip in downward position." -- Ushio/BLV

After certain people made an issue of this by claiming that it made no difference, I spent an entire day googling it and came up with independent confirmation on two different websites written by guys who are engineers in the business of making the damn things.

[Reefland]

My SLS fixtures only allow the bulbs to be put in one way, nipple up.

[step_up]

On the odyssea HQI fixure I have the bulbs have to go in the exact way the old bulbs came out. The nipple facing up and even the direction of the bulb mattered. I expiermented with it last time I replaced bulbs. They would not fire when nipple faced down at all. They also would not fire if I just changed the direction of the bulb. This may very well be different with other brands.