Hi Rick,
The translation of the torque requirement is about five inch pounds if I
remember it correctly. You can purchase a torque screwdriver which will read
in inch pounds from most commercial tool suppliers. However, if you don't
wish to spend the money (they can run up to several hundred dollars), there
is an easy way of tightening the autosampler plates.
With the four main bolts completely loose, wrap your fingers (thumb and
middle finger) around the top of the autosampler so that the tips of your
fingers are in the small (about 1-2 mm) gap between the top plate and the
body of the autosampler. Using your fingers, hold the top plate so it is
level (the gap should be the same on both sides). Now, tighten one of the
bolts until you feel it start to pinch your fingertip and then stop. Pick a
bolt diagonally to the first bolt and tighten until it starts to pinch your
fingertip, then stop. Do this for the remaining two bolts. You can now
remove your hand from the autosampler.
Pick one of the bolts and turn it one complete turn, then go to the diagonal
bolt and tighten it one complete turn. Continue for the remaining two bolts.
You will need about 4 turns on each bolt to get it to the correct tightness.
You didn't say what the condition the plates are, and whether the slide was
old or new. That will have an effect on how tight to make the autosampler.
Put the AS/200 back on the instrument and move the slide manually by
reversing the blue air lines. It should move smoothly and at the right
speed. Perform a leak test with the autosampler slide in the back and
forward positions. If you have a leak in one position or the other, try
tightening the four bolts an extra 1/2 turn. Move the autosampler a few
times manually, and then run the leak check again. Tighten the plates to the
minimum required to get a seal. If you over tighten the plates you can cause
a blister to form on the Teflon slide. You cannot damage the AS/200 by
tightening the bolts too much (other than the slide); the worst that will
happen is the slide will not move.
If you have one of the older analyzers and can set up a short cycle time,
and use it to "seat" the slide. Set the cycle time on the analyzer for 10
seconds, set the sample start for 1 second, and sample stop for 5 seconds.
Press down the OXY INJ button to inhibit the oxygen as well as the NO PEAK
STOP button. Press the manual start, and let the system cycle at least 50
times. Check for leaks again.
When the system is tight, try running a couple of blanks (no tin capsule)
with the oxygen inhibited. If the nitrogen blank is normal, then you're
done. There's no need to take the autosampler apart again.
Best regards,
Bruno Lavettre
Costech Analytical Technologies, Inc.
-----Original Message-----
From: Stable Isotope Geochemistry [mailto:[log in to unmask]] On Behalf
Of Rick Heemskerk
Sent: Tuesday, January 31, 2006 8:36 AM
To: [log in to unmask]
Subject: Carlo Erba AS 200-LS
has anyone got the torque setting required for tightening the 4 bolts on the
Carlo Erba
AS 200-LS solid auto sampler pressure plate? The instructions say up to 5 kg
per
square cm (pressure?). It is supposed to be re-tighted later to 4 kg per
square cm after
letting the new slide "bed in".
thanks
Rick
A. Richard Heemskerk [log in to unmask]
Environmental Isotope Laboratory Telephone: 519-888-4567
Department of Earth Sciences Extension: 5838
University of Waterloo Facsimile: 519-746-7484
Waterloo, Ontario, Canada N2L 3G1
http://sciborg.uwaterloo.ca/research_groups/eilab
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