Maintenance Page

Note that if you want some comments from us concerning any of the instrument maintenance that isn't on this page, then please feel free to contact the lab manager and ask.

I] EA

i) replacing quartz inserts

ii) replacing/repacking the combustion tube

iii) replacing/repacking the reduction tube

iv) repacking the Mg(ClO4)2 (magnesium perchlorate) water trap

v) cleaning the zero blank autosampler

II] TC/EA

III] TIC/TOC

IV] GC/C-TC

V] GasBench

VI] Mass Spec Maintenance

i) Oil Change

ii) MAT 253 ion source disassembly (this links to a power point presentation showing details of disassembly)

maintenance quartz tube.jpg

I] EA Maintenance

i) replacing quartz inserts

ii) replacing/repacking the combustion tube

On September 26th, 2005 the Delta Plus and MAT 253 were shut down for an oil change. As an extra safety measure, the main switch was turned off (which isn't necessary or recommended in the future). As both the EA and TC/EA were plugged into the Delta Plus, this meant that they were also shut off. The rapid cooling of the combustion tube in the EA resulted in it cracking and subsequently emptying the helium tank that is plumbed into it. This unfortunate event was an opportune moment to replace the combustion tube for the first time! We had purchased an extra, prepacked combustion tube from Costech earlier so the change was very easy. We now pack our own combustion tubes. The first picture on the right shows a new combustion tube with a quartz insert in it. The second picture shows our used reduction tube after an estimated 600 samples. Gas flow comes in through the bottom of the tube where oxygen (as O2 or as NxOy) is trapped in the form of CuO (black).

iii) replacing/repacking the reduction tube

On the day that the combustion tube cracked, we went ahead and replaced the reduction tube as well. Although the tube was in perfect shape and could have been repacked, we chose to keep it for show and tell and repacked a new tube with copper wire.

The new, prepacked combustion tubes with quartz insert (on left) come with a piece of plastic tubing in them that should be removed. Used reduction tube (on right) after an estimated 600 samples. Gas flow comes in through the bottom where oxygen is trapped as CuO (the black stuff).

Maintenance_EA_Reduction_tubes.jpg

  iv) This is what your data will look like if you do not replace the copper in the reduction reactor before it is depleted.

NOformingwithN2.JPG

Note the peak occuring on the m/z 30 trace. This is NO (nitrous oxide) which has obviously not been reduced in the reduction furnace. It's not a good thing when all of the nitrogen has not been reduced to N2. If you see such peaks in your data then your reduction reactor is probably spent. In general we get about 1000 runs safely. After that we replace both the oxidation and reduction reactors.