Isotopers,

We are cleaning and refurbishing the source on our FMAT Delta Plus XL after
having some problems with a growing H3 factor and emission. We pulled the
source to clean the ion box and plates and noticed that the third quartz
insulator was chipped on each side.  We order replacement insulators from
FMAT and some of the replacement parts that we received,  much to our
surprise, were ceramic and not quartz.  In our MAT 251 we changed out the
original ceramic insulators for quartz and have been very happy with faster
pump down, lower backgrounds and increased sensitivity.  I thought all new
Deltas were supplied with quartz insulators in the source as well.

So my question to the list is how important is it to have quartz spacers in
the source of a continuous flow instrument (as opposed to ceramic spacers)?
I know that quartz insulators are more fragile than ceramic over the long
haul, but less prone to contamination.  I was surprised to see how clean
the plates and ion box in the Delta source was after ~75,000 analyses.  But
I've been down the ceramic insulator road before, and have been more happy
with quartz insulators at least in a static instrument.  I would appreciate
comments especially from anyone running hydrogen and carbon monoxide.

Thanks,
Bill


William J. Showers
Dept of Marine, Earth & Atm Sciences
Box 8208
North Carolina State University
Raleigh NC 27695

For express mail: 1125 Faucette Dr.

(919) 515 - 7143 Office
(919) 515 - 7802 Fax
(919) 515 - 3689 Lab
(919) 515 - 7911 Field Lab
[log in to unmask]

Visit our RiverNet Web Site
http://rivernet.ncsu.edu

"We do not inherit this land from our ancestors;
we borrow it from our children."
Haida Indian Saying