APPENDIX 

 Operation of Oxygen -Temperature Meter 



1 . Prepare a solution of 0.5N KOH. (28 grams plus distilled water to make 1 liter.) 



2. Place about 100 cc . of this electrolyte in small glass jar and label "For Polarization". This 

 solution may be saved and used several times. Ettscard when discoloration appears. 



3 . Clean the silver tube with very fine steel wool or emery cloth (#500) and rinse with alcohol or 

 distilled water. Make sure electrode is free of steel wool or emery dust. The platinum disc 

 will need only occasional cleaning. Do not sand it each time the silver is cleaned. 



4. Place the electrode in the polarization solution and make sure the electrolyte completely 

 covers the silver. Plug cable into socket. Turn switch to "Pol". Leave on until silver turns 

 black or brown (about 30 - 60 seconds) . 



5. Turn switch to "Off" and remove electrode. Blot off excess KOH, but do not wipe. Allow 

 electrode to dry 2-3 minutes. 



6. Place a 4 -inch square piece of the Teflon or polyethylene membrane in palm of hand and cup 

 sligjitly. Place dime-size drop of 0.5N KOH (from stock, not that used for polarization) on 

 the membrane . Place the electrode in drop and draw the membrane smoothly around all sides 

 and up over the groove at top. Hold the electrode pointed down and place "0"-ring around end 

 of electrode and roll or slide upward until it seats in "0" -groove. 



7. Smooth the membrane again and trim off excess membrane above the "0"-ring. 



8. Put the prepared electrode in water and turn switch to "O2 Read" position. Leave on for 30 

 minutes - 1 hour to equiUbrate. 



9. Prepare saturated O2 water (cool distilled water below room temperature) and aerate several 

 hours; then warm it to room temperature and shake vigorously several times. 



10. Place electrode in this standardized water and stir water or move electrode. 



11. Turn switch to "Adj." and adjust needle to red line. Turn to "T. Read" and note temperature. 



12. From the "Temperature compensation card" find the counter number corresponding to this 

 temperature and set this number on the counter dial. This procedure compensates the electrode 

 for temperature. 



13 . Turn switch to O2 position and allow reading to become steady (about 1-2 minutes) stirring all 

 the time Record this reading (lower numbers on regular meter scale) for example 16.7 ua. 



14. On saturation table find the ppm O2 at the determined temperature. This is one point on a 

 graph (see next paragraph) . 



15. Place electrode in small container of water (250 - 500 cc. or the storage bottle), add sodium 



sulfite (1-2 grams) and stir until neddle indication stops going down (around 0.3 ua). This is 



Zero O2 (the residual current), the second point on the graph. Draw straigjit line on graph 



(appendix figure) between these two points. Subsequent determinations of oxygen in unknown 



samples may be made by reference to this graph; i.e. by finding the ppm O2 that corresponds 



with other meter readings. 



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