From: Sandy King (sanking@clemson.edu)
Date: 07/10/02-09:36:01 PM Z
Halvor,
HID is an abbreviation for High Intensity Discharge. HID bulbs are
made in sodium vapor, mercury vapor and metal halide. Only the last
two types are useful as exposure units for alternative processes. As
you note, HID bulbs are routinely available in configurations up to
1000 watts, and less commonly up to 4000 watts and above.
To the best of my knowledge mercury vapor lamps are at least as
effective as metal halide bulbs as exposing units for alternative
processes. In fact the two types of bulbs are very similar in terms
of spikes of radiation, so much so that when you look at the SPD
curves for the two types you realize that the metal halide is really
just a mercury vapor + lamp, with most of the + radiation in the
visible light area not useful to alternative processes.
As noted earlier, HID mercury vapor and metal halide bulbs are
available commercially in ballasted luminaire units of up to 1000
watts. Self-ballasted HID mercury vapor bulbs are available in up to
750 watt size, though many bulbs of this type appear to have a
phosphor coating that shields UV light.
Sandy King
>There exist something called HID bulbs can be obtained up to at least 1000
>watt (if I remember right) bit expensive - and big - but still a bulb. They
>should also in theory have a better uv coverage than mercury bulbs. I have a
>500 wats version which I havnt got around to test yet. Do not have the
>details of maker and so right here and now but email me and if interesting
>and I will dig it out. (or is this the metal halide in a different name ?)
>
>Halvor
>
>on 11.07.02 03:08, Sandy King at sanking@clemson.edu wrote:
>
>>
>> Just a brief addition to the previous message as regards self
>> ballasted mercury vapor lamps. These lights can be used without
>> ballast in incandescent fixtures rated for the wattage. However, most
>> of the high wattage lamps of this type appear to have a phosphor
>> coating which shields some of the UV light. A brief search on the web
>> found a couple of 150 watt units that may be of interest to some.
>>
>> http://homeharvest.com/spotgrowlightbulbs.htm
>>
>> http://www.zoomed.com/html/powersun_uv.html
>>
>> Possibly bulbs of this type are available in higher wattage but I
>> have not so far found a source. As is I suspect they will perform
>> much like the old sunlamps one used to be able to buy.
>>
>> Sandy King
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>> Bob,
>>>
>>> The 175 watt mercury vapor street lamps are inexpensive but they are
>>> far from what I would call a powerful light source. At a distance of
>>> 18-20" from the printing frame I found exposure times to be be
>>> unbearably long when using just one of these lamps.
>>>
>>> A much better source in my opinion would be a 400 or 1000 watt metal
>>> halide or mercury vapor lamp, in proper housing plus ballast. Also,
>>> self-ballasted mercury vapor lamps of in 250, 450 and 750 watts are
>>> also available.
>>>
>>> In considering the use of a metal halide or mercury vapor lamp of
>>> any size one should bear in mind that the most important
>>> consideration after wattage is whether the lamp is coated or clear.
>>> Coating, which is generally done to improve the visual qualities of
>>> the light, serves as a filter to UV light and is quite undesirable
>>> for our needs.
>>>
>>> Sandy
>>>
>>>
>>>
>>>
>>>> Philippe,
>>>>
>>>> I don't know if you can buy one of these in Belgium, but over here
>>>> its possible to buy a 150 watt mercury vapor street lamp complete
>>>> with clear glass bulb for about $35 (35 euro or 175 FF). At a
>>>> distance of about a half a meter they make a fair approximation of
>>>> a point source and they have a long lifetime.
>>>>
>>>> Bob Schramm
>>>>
>>>>> From: Monnoyer Philippe <monnoyer@imec.be>
>>>>> Reply-To: alt-photo-process-l@sask.usask.ca
>>>>> To: alt-photo-process-l@sask.usask.ca
>>>>> Subject: Powerfull UV point source
>>>>> Date: Tue, 09 Jul 2002 10:08:26 +0200
>>>>>
>>>>> Hello everybody,
>>>>>
>>>>> I might want to switch from UV tubes to a powerfull point source in UV.
> >>>> What can I find for such a source ? Is it reasonable price ?
>>>>>
>>>>> See you all in APIS ?
>>>>>
>>>>> Philippe
>>>>> Belgium
>>>>
>>>>
>>>> Check out my web page at:
>>>>
>>>> http://www.SchrammStudio.com
>>>>
>>>> also look at:
>>>>
>>>> http://www.wlsc.wvnet.edu/www/pubrel/photo.html
>>>>
>>>> _________________________________________________________________
>>>> MSN Photos is the easiest way to share and print your photos:
>>>> http://photos.msn.com/support/worldwide.aspx
>>>
>>>
>>> --
>>
--
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