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<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial>Peter, what, did Beckman sell you a lemon? It seems you have
trouble constantly.</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial>Borries has a good point about pump oil and high temperatures,
but my best guess is that you still have a vacuum leak somewhere. Here is a
'rule of thumb' leak diagnostic:</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial>After the instrument has been through a couple of runs, and
thus the water vapor in the mechanical pump oil has worked its way
out, monitor the vacuum reading during the initial pump down
as the pressure drops through the region from ~400 to ~200 microns.
The successive readings (updates on the CRT) should go down by ~1% of the
previous reading. That is, it should go like 400, 396, 392...306, 303,
300...204, 202, 200. The pattern won't actually be that even of
course, but you get the idea. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial>When the instrument has been run a lot and things are
<U>really</U> clean it should go down even faster than that (perhaps ~1.5% per
update). If the pressure is dropping significantly less rapidly than
this '1% rule of thumb' then that is an indication you probably have a
leak. </FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial>As to leak location, to me the fact that the lamp is getting
dirty so quickly suggests the leak is right there at the lamp (despite the new
lamp o-ring).</FONT></SPAN></DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial></FONT></SPAN> </DIV>
<DIV dir=ltr align=left><SPAN class=339094022-16022012><FONT color=#0000ff
size=2 face=Arial>John</FONT></SPAN></DIV><BR>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left>
<HR tabIndex=-1>
<FONT size=2 face=Tahoma><B>From:</B> rasmb-bounces@rasmb.bbri.org
[mailto:rasmb-bounces@rasmb.bbri.org] <B>On Behalf Of </B>Peter Edward Prevelige
Jr<BR><B>Sent:</B> Thursday, February 16, 2012 1:56 PM<BR><B>To:</B>
rasmb@rasmb.bbri.org<BR><B>Subject:</B> [RASMB] Rucrrent Dirty Lamp & Maybe
Slow to Pump Down<BR></FONT><BR></DIV>
<DIV></DIV>
<DIV class=WordSection1>
<P class=MsoNormal>Hi All –<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>I am having trouble with my lamp getting dirty after only a
couple of days. The instrument was just serviced. A new lamp and gasket
were installed because of a vacuum leak and afterward the lamp intensity
and noise level looked great.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>A couple of runs later the noise @280 was too high and when I
checked the UV intensity it was down to maybe 4K at the 230 peak. Cleaned
& aligned the lamp and it was back up to 15K+ counts. Three days and 4
SedV runs and was back down to 4K. Cleaned and aligned it and it is back up to
17K counts. My impression also is that it is slow to pump down but this is
of course subjective.<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>It seems like it is getting dirty much too fast. Certainly we
never had to clean it after every few runs. In any case, it seems to be getting
dirty too fast for a good Sed EQ run in the far UV at any rate. Any suggestions
on what to look for/do?<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Thanks<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal>Peter<o:p></o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><o:p> </o:p></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">Peter
E. Prevelige Jr.<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">Professor<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">Dept.
of Microbiology, BBRB 416/6<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">Univ.
of Alabama @ Birmingham<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">845
19th St. South<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN
style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">Birmingham AL.
35294-2170<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">Phone
205 975-5327<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt">FAX
205 975-5479<o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt"><A
href="mailto:prevelig@uab.edu">prevelig@uab.edu</A><o:p></o:p></SPAN></P>
<P class=MsoNormal><SPAN style="FONT-FAMILY: Consolas; FONT-SIZE: 10.5pt"><A
href="http://www.microbio.uab.edu/faculty/prevelige/prevelige-p.htm">http://www.microbio.uab.edu/faculty/prevelige/prevelige-p.htm</A><o:p></o:p></SPAN></P>
<P class=MsoNormal><o:p> </o:p></P></DIV></BODY></HTML>