More about capillaries...One cannot infer anything about the ID of fused
silica capillary tubing by looking at the OD.  Depending on the supplier,
tubing with smaller ID's may have somewhat larger OD's, especially the
220-200 um and the 100-75 um sizes. Has to do with something about wall
thickness, structural stability and the manufacturing process.  The ID is
the only thing that counts.  And for the Finnigan instruments, I have only
ever both seen and used a sample capillary ID of 100 um and the refgas
capillary ID of 75um.  I start them out at 1.5 meters long, so that when I
work behind the instrument and break them off due to a errant elbow, I
still have something to work with....
Clear as mud? Bob Dias


At 05:02 PM 1/28/99 -0800, you wrote:
>Dear Dr. Tsunogai,
>  Your original question is still a good one which has not been answered. In
>spite of the logic of Bob Dias's reply, confirmed by H-J Schluter, our GCC
>III ALSO has capillaries in which the larger outer diameter capillary is the
>standard, not the sample. Since our system works well I'm not about to take
>it apart right now to confirm this, but perhaps the larger outer diameter
>capillary has the smaller INTERNAL diameter of the two?
>
>David Wilbur                      206-685-9288
>Stable Isotope Lab             206-685-2366
>School of Oceanography   206-685-3351 fax
>Box 357940                       [log in to unmask]
>Univ. of Washington
>Seattle, WA 98195-7940 USA
>http://www.ocean.washington.edu/people/staff/dowilbur/dowilbur.html
>
>
>
>
>>Dear Drs. Schl $B]U (Jer and Dias,
>>
>>Thank you for your kind answers and suggestions.
>>I am sorry but I probably made a wrong English translation in my previous
>>question.
>>
>>What I want to ask was concerning to the difference in "diameters" of the
>>two capillaries. The lengths of the capillaries were almost the same. In
>our
>>Combustion III system, however, the diameter of the capillary for sample
>gas
>>is apparently shorter than that for reference gas. As described by Bob, and
>>also in our service manual, shouldn't they be opposite? I guess the
>diameter
>>of the capillary for sample gas must be longer to get lower split ratio at
>>open split for sample measurement. Or I make some misleading again?
>>
>>Sincerely,
>>Urumu Tsunogai
>>
>>
>>
>>
>>
>>
>>--------------------------------------------
>>Urumu Tsunogai, Dr. Sci.
>>Dept. Environ. Science & Technology, IGSSE
>>Tokyo Institute of Technology
>>4259 Nagatsuta-cho, Midori-ku,
>>Yokohama 226-8502, Japan
>>Tel. +81-45-924-5555 (or 5554)
>>Fax. +81-45-924-5554
>>E-mail [log in to unmask]
>>---------------------------------------------
>>
>