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Karen Lovely-Leach
MacGuire LSB- Room 326
Amherst College
Amherst, MA 01002
413-542-2081
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Hi everyone,
I started running our new confocal facility a little over a year ago
with an LSM5 Pascal. Last year we got the recommended 200 hours out of
the HBO100 W/2, after which it began to stutter on ignition, and we
changed it promptly. Because we use it most of the time to locate cells
and quickly look for staining, we started running it at 20%, and since
then we have logged approximately 750 hours. Now I am getting nervous
with thoughts of explosions, so I am going to replace it!
I found all of the conversation on this topic very helpful. Karen
-----Original Message-----
From: Confocal Microscopy List [mailto:[log in to unmask]] On
Behalf Of Dale Callaham
Sent: Friday, April 25, 2008 6:07 PM
To: [log in to unmask]
Subject: Re: HBO/Mercury lamp lifetimes
Search the CONFOCAL archive at
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Hi,
I have seen strong recommendations against forced air cooling where arc
stability is a prime concern. Osram literature states that forced air is
not needed if sufficient convection through the lamp housing will keep
the bases below 230C and most commercial designs probably do this. They
state that any cooling should "not be directed at the discharge vessel".
Most recent lamp housings and lamp mountings assist the upper base
cooling with a heatsink. I bolted a thermocouple to the upper base (-
terminal) of a unit (leave TC disconnected until after ignition!) and
measured only 180C for a new lamp; the lamp has to get hot to function
properly. Staying with well-designed equipment in good operating
condition (check for oxidation of leads and connectors and replace if
necessary) it shouldn't be necessary to use forced air.
I am curious - someone mentioned the Zeiss AttoArc - doesn't that allow
you to run at lower than max/nominal settings? Seems that many arclamps
are too bright and need attenuation anyway; I was wondering if anyone
runs them at lower levels as a standby condition between users or for
lower excitation and does it seem to extend the life? I built a unit
that could run a HBO 100W/2 nicely below 1A (they have a 5A nominal
current) but I didn't get to monitor the performance over a long period.
Dale
Ignatius, Mike wrote:
> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> An important side bar in this discussion, is what warning signs are
> there that the bulb is too old and possibly going to fail/explode.
>
> For me, the earliest signs that the arc gap has grown to impossible
> widths were difficulty in starting the bulb to begin with, flickering
> when on, long time to stabilize etc.
>
> The more dreadful indication is an electrical burning smell when it is
> on and about to blow.
>
> In my one experience it smelled like insulation burning off of wiring.
> Apparently the bulb super heats before failure? I would be curious to
> hear if others have had this warning sign before the bulb blew. I
> stupidly got up, and sniffed around the scope to see what the source
was
> and wham the bulb blew in my face. I thanked Nikon for their sturdy
> housing, no glass came through, though the diffuser lens inside did
> shatter, and the mercury vapor surely escaped. After it has blown,
> always good to leave the area for a while to let the gas escape.
>
> My recommendation: if you smell electrical burning, turn off the lamp
> and check your bulb! If the smell persists, something else is amiss.
>
> And no one has mentioned benefits to running cooling fans across
housing
> this time around. It seems to help extend lamp life.
>
> Mike Ignatius
>
> -----Original Message-----
> From: Confocal Microscopy List [mailto:[log in to unmask]]
On
> Behalf Of Russell Spear
> Sent: Friday, April 25, 2008 7:58 AM
> To: [log in to unmask]
> Subject: Re: HBO/Mercury lamp lifetimes
>
> Search the CONFOCAL archive at
> http://listserv.acsu.buffalo.edu/cgi-bin/wa?S1=confocal
>
> I've been using HBO 100 W s, for about 30 years, and have had 2
> explosions in that time, one long ago and one approx. 3 yrs past.
Both
> could be attributed to a high number of on off cycles (something I
> discourage). I nomally cycle a bulb no more than twice a day, and
need
> to relamp about every 40-45 days in a busy lab with 3 fluorescent
> scopes. We always replace at 200 hrs. the cost of the bulb is small
> compared to the damage to the equipment and time and cost of
> decontaminating the microscope rooms.
>
> Russ
>
>
>
> Russell N. Spear
> Sr. Research Specialist
> Dept. of Plant Pathology
> Univ. of Wisconsin
> 1630 Linden Dr.
> Madison WI 53706
>
> voice 608.263.2093
> fax 608.263.2626
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