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Old 10-16-2014, 08:44 AM   #3 (permalink)
JOHN @ URI
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Location: Cleveland, Ohio
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Re: Dim center in lamps

We sell all brands & see it with almost all 2 meter lamps in certain applications. Usually it corrects itself with proper lamp burn in & proper operating temp.

One would think the brighter the lamp the better the output, that is not always true.
The brightness is visible light, which plays no part in UV output.

Here is part of technical bulletin from a lamp manufacturer on VHO lamps:

Quote:
Occasionally lamps of this type will exhibit what is seen as a slow warm up. This is typical when the bulbs have been off for an extended period of time, especially if left in a cool environment. This can also be caused by excess cooling on the lamp ends. These circumstances cause the mercury vapor to migrate to the lamp ends and condense. This is generally corrected by operating the lamps for a period of about 60 minutes to allow the mercury to be re-distributed in the lamps.

Tanning customers may also see what they perceive as visual color variations, especially in new lamps. This is caused during the lamps normal ‘break in’ period while the lamps are stabilizing the mercury vapor. This variation will generally go away after one or two hours of lamp operation. Customers should not relate visible brightness to
U.V. intensity. We recommend all tanning salons to have a U.V. meter to be able to monitor lamps for maintenance and proper operation.

In order to determine if a lamp is being cooled properly we recommend the following procedure. First, operate the lamps for several hours in the tanning unit in the usual operating manner in order to stabilize the mercury. Next, allow the lamps to cool completely and turn off the cooling fans to the system. Now turn on the lamps and monitor the highest reading the lamps reach during their warm up. This will usually occur within one to two minutes then the readings will drop off. The peak reading is the point where the lamp passes the optimum temperature. Allow the lamps to again fully cool and reconnect the cooling system. Turn the lamps back on with the cooling system running and again watch the warm up of the lamp. If the lamp takes more than one or two minutes to reach the peak reading previously recorded, then the lamps are probably being over cooled. If the lamps quickly reach the peak and then drop by more than about ten percent, then the lamps are not being adequately cooled. Ideally, the lamps should reach the peak in one to two minutes, drop slightly and become stable for the remainder of the session
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