7/19/96
Having been told it never happens we have had two in the last 5 months and a
lab in a neighbouring hospital has had one, the last two within a week of
each other.
All the bulbs exploded within their lifespan (180 hrs, 180hrs and 80hrs)
and were treated properly ie only switched on once a day and left running as
long as possible.
Does anyone know another source of bulbs - these were Osram 100W and 50W bulbs.
If you don't want to bore the list within another long discussion on bulbs
please e-mail responses.
Elaine Levy PhD
Cytogenetics Group
Wellcome Trust Centre For Human Genetics
Windmill Rd.,
Oxford OX3 7BN
tel 01865 740022
fax 01865 742186
email elaine.levy@well.ox.ac.uk
if we are taking a poll to see if there is a national problem in bulb
quality add us to the list.
We have never previously had a problem. Routinely retired bulbs at about
200 hours. We just had one explode at 47 hours. We have checked our
equipment and could find nothing wrong (this of course does not rule out
an equipment problem).
Jay Jerome
Dept. of Pathology
Bowman Gray School of Medicine of Wake Forest University
Medical Center Blvd
Winston-Salem, NC 27157-1092
910-716-4972
jjerome@bgsm.edu
may I allow myself to suggest some possible mistake which, if
done during the alignment of the lamps, causes the lamps to
overheat and then explode. I do NOT intend to have this state-
ment as an insult, it is just a suggestion that there might be a
false way of alignment due to not having properly read the manu-
al. I have to write this since some biologists have become angry
when I had suggested that they might have done what they called
"primitive schoolboy mistakes." During the last years, I had seen
in two cases that persons had aligned the reflectors mounted in
Zeiss or Nikon lamp housings for Mercury or Xenon lamps improper-
ly.They had done so intentionally in order to get an illumination
of the field of view which was more uniform as it would have been
upon alignment according to the precsriptures.
The mistake which is, as it seems, done now and then, is that
both, the image of the arc and the image of the reflected arc are
centered. The consequence is, that the mirror, like a magnifica-
tion glass you use to set fire on a sheet of paper using sun-
light, focusses all the light escaping towards the 2 pi part of
the solid angle not covered by the condensor lense of the lamp,
back into the lamp, causing a tremendouse heat inside which will
blow up the lamp within short.
When aligning the bulb resp. the mirror, five screws must be ad-
justed besides the focus-position of the condensor. Two of the
screws control the lateral positioning of the lamp, three the la-
teral and focal positioning of the reflecting spherical mirror.
It is a little bit difficult to describe this in an email without
any scheme.
Take off the microscope objective. Adjust the microscope stage
to ca. 45mm distance from the tap for the objective (this is the
standard distance as accepted by as far as I know all mic-
producers and it is called "Abgleichl{nge" in german language, in
which most of the terms in microscopy are, unfortunately, defined
exclusively). Insert a set reflection filters for fluorescence.
Place a sheet of white paper on the stage. Adjust the focus of
the lamp-condensor lense so that you (hopefully) see a sharp im-
age of the arc on the paper. If you do not manage to do this,
then the lateral positioning of your bulb is so far out of the
center that you have to do a coarse prealignment offline, first.
Tell me, if you want a description of how to do that. Now, once
the image of the arc is sharp, it should be positioned in the
left or in the right half circle of the field of view, NOT in the
centre. This positioning is done using the height control screw
and the side-positioning control screw of the lamp-housing. The
height positioning screw is accessible from the top of the lamp
housing, the lateral positioning is controlled by one of the
screws on the rear side of the lamp housing (this is valid for
Zeiss and Nikon, not do I know for Olympus and Leica). Now, using
the three remaining control screws, adjust the reflective mirror
of your lamp so that the image of the reflected arc is focussed
sharply into the second half of the field of view on the paper.
It might, of course, be that you have not done this error in
which case my letter should be regarded as meaningless.
I wish you good success.
Paul Johannes Helm
Mailadress: Department Physics 4
The Royal Insitute of Technology
S-100 44 Stockholm
Sweden
oice: +46 8 790 7219
Fax: +46 8 205609
Telex: 11421 kth
WWW: http://www.fysik4.kth.se/~johannes
>email: johannes@fysik4.kth.se
I've had one explode in ten years. As to the USHIO bulbs: we may have had
a bad bulb, but I recently replaceda USHIO HBO 102 at 150hrs with a OSRAM
HBO 100 and tripled the light output from our system. As a result, I have
become somewhat suspicious of USHIO bulbs. Anyone else have bad (or good)
experiences with USHIO?
.
Peter Guthrie
Department of Neurobiology & Anatomy
University of Utah School of Medicine
50 N Medical Drive
Salt Lake City, UT 84132
(801) 581-8336 (801) 581-4233 fax
pguthrie@med.utah.edu
of the lamp for imaging purposes?
If so how is it mounted? Vertical or at an angle?
Tom Donnelly
DeltaVision Systems
Applied Precision, Inc .
8505 S.E. 68th St.
Mercer Island, WA 98040
206-230-4249 tel
206-232-4184 fax
tdonne@api.com
Web Site: http://www.api.com
interest in this vein. First, in the 100 Watt Hg lamps the electrode
spacing is very close and if the reflected arc image should fall onto one
of the electrodes there will certainly be overheating of the electrode and
chance of explosion.
A second point is that the power supplies used can be a large influence on
the lamp heating. The arc voltage varies with operating temperature and
always increases (at a given current) as the electrodes burn back with
age. In power supplies that regulate to a fixed lamp current there will be
a continuous increase in the power dissipation of a lamp over time with
the possibility of overheating. Osram specifies a maximum temperature of
the lamp bases as 230 C (200 C is better).
It sounds like most of these failures that have appeared on the list have
occurred in equipment with a track record where only the lamp had been
changed recently: is this correct? This would indicate a difference in
the lamps that are being supplied.
Dale A. Callaham
Central Microscopy Facility
University of Massachusetts
Amherst, MA 01003 USA
email: dac@bio.umass.edu
lamp(s) refused to start.
I called OSRAM to ask if this was a general problem, and they said it
actually was. They said they changed something in the manufacturing process
of the bulbs, and the new bulbs might need a slightly higher ignition
voltage. They recommended to talk to the microscope manufacturer about a
new power supply! Old lamps were not available anymore.
I called Zeiss, and again they were not surprised at all. They said there
was indeed a problem with new lamps. A Zeiss representative dropped by and
checked another lamp and suggested to use the special 'knob' on the power
supply whenever ignition didn't work.
The lamp still works, but the reports of exploding bulbs makes me nervous.
Dr. Petra M. Nederlof
Max-Planck-Institute for Biochemistry
Dept. Structural Biology
Am Klopferspitz 18 A, D-82152 Martinsried (Munich)
GERMANY
Tel: +49 (0)89 8578 2624
Fax: +49 (0)89 8578 2641
email nederlof@alf.biochem.mpg.de
there was a world wide surge in lamps exploding well inside their due time.
We had thought it was a local problem at first, due to the extreme
fluctuations in mains power we used to get, and put all our transformers on
a regulated power supply. It didn't work. We put cooling fans on our lamp
houses. We couldn't get that right to avoid running them so cool that no
useful light came out. In the end we corresponded with the manufacturers
(Osram) and got all the standard advice (regular power, leave on for long
times, hands off the glass etc) but no real solutions...
In a chance discussion at a meeting in Europe it
turned out that many labs were having the same problem with 50W burners.
The story that was out was that there was a particular person who had
worked making the bulbs (or supervising their manufacture) for years and
years and that he had retired....and then it took some time for the
standard to come up to scratch again....
I don't know if this story is true or not (it would be good to have it
confirmed one way or the other) but if it is, then perhaps the staff or
methods have changed again...
Ushio in Japan makes good bulbs (they come supplied with Olympus
microscopes) although I think they are more expensive than the Osram ones.
This probably hasn't been much assistance, but I agree it would certainly
help to know if this is a widespread problem looming up again...
IAN
Professor Ian Gibbins
Department of Anatomy and Histology
Flinders University of South Australia
GPO Box 2100 Adelaide 5001
AUSTRALIA
Phone: +61-8-2045271
FAX: +61-8-2770085
e-mail: Ian.Gibbins@flinders.edu.au
When I was using a 1 kW high-pressure Hg lamp, one blew out
just as I reached out to adjust the air flow--it made quite an im-
pression. When I called the company about repair of the housing,
they told me that this was the usual method of failure. The solu-
tion I used was to turn on the lamp and leave it on for the duration
of the experiment (and to run the experiment 24 hours a day). Since
I was doing a series of photochemistry experiments at different ex-
posures and wavelengths, this was feasible, although I had to come
into the lab at odd hours. Having the lamp on continuously extended
its lifetime by a large factor. After the experiment was done and
the lamp was shut off, it was discarded--before it blew. This may
not be a practical solution for you, but the key is not to subject
the lamp to more thermal stress (by turning it on and off) than ab-
solutely necessary, and to discard it before it explodes. Good luck.
Bill Tivol
tivol@wadsworth.org
was very concerned about the exposure to mercury vapor. Since we are in a
university setting, I called our Health Protection Office for advice. They said
to consult the manufacturers data that accompanies replacement bulbs. The data
sheet says to clear the area, and allow the ventilation system to exchange the
air in the room. HPO didn't think that there would be enough liquid mercury to warrant
trying to wipe down the area. Consult the manufacturer of the lamp in question.
Randy Nessler
rnessler@emiris.iaf.uiowa.edu
the rated life of the burner and I had two 200W lamps explode due to a
faulty power supply.
WHAT TO DO:
1) Close off the room immediately. This is mercury vapor (a small amount,
but mercury vapor is highly toxic (it has been known to kill careless gold
amalgamators). You want the mercury to return to liquid form. It is going
to be in a few places.
2) call your institutional safety officers and find out what they do for a
mercury cleanup. This is not a great amount of mercury, but they may want
to deal with it according to your local environmental laws.
3) After that, you're going to have to check the condition of your lamp
housing. If you have a lamp housing with a parabolic mirror, it may have
been shattered by the explosion and you will have to send it back to the
manufacturer for repair.
4) Determine the cause of the blowup. Posible ones are:
a) use beyond rated life. This is the most common cause of lampo blowout.
The glass inside the burners gradually gets coated inside with a gray or
black film, even with proper use. This will lead to the lamp burning hotter
as it nears the end of its rated life. Eventually, booom!
As I understand it rated lives are as follows:
50W HBO 100 hrs
100W HBO 200 hrs
200w HBO 400 hrs
(Anyone please correct me if I am misinformed on this point).
b) improper alignment of the burner. If there is a parabolic mirror in your
lamp housing, it is important that you do not overlap the mirror image of
the arc with the real image. This can easily lead to oveheating of the high
pressure bulb. Refer to the manual for your lamp housing for arc alignment
instructions.
c) Faulty power supply. Occasionally, a power supply may overload the
burner. As I stated, I have had this happen a couple of times. Get the
power supply either replaced or repaired.
I hope this helps you and others on the list. Please add any other useful
commments.
Matthew J. Schibler, Ph.D.
Cell Imaging Facility
The Burnham Institute
(La Jolla Cancer Research Foundation)
10901 North Torrey Pines Road
La Jolla, CA 92037
P (619) 455-6480 x3206
F (619) 646-3197
E-mail: schibler@ljcrf.edu