EQUIPMENT--YSI Model 32 Conductance Meters

In Reply Refer To:                           June 22, 1981
EGS-Mail Stop 412


QUALITY OF WATER BRANCH TECHNICAL MEMORANDUM NO. 81.17


Subject: EQUIPMENT--YSI Model 32 Conductance Meters

The Yellow Springs Instrument Company has recently advised us 
of a possible component failure in some of their newer model 
32 digital conductance meters. If you have one of these 
meters you are advised to perform the test described by YSI 
in the enclosed Dealer Service Memo and follow their advice 
should your instrument fail the test. If you have an 
instrument with one of the listed serial numbers and it 
passes the test, I would still advise you to have it checked 
by the company.

There have been some complaints concerning difficulties in 
measuring the specific conductance of very low ionic strength 
precipitation samples when using the glass microcell with the 
Model 32. Until a reliable operational procedure can be 
checked and verified, you are advised to either use a 
standard cell for the measurement or make both a temperature 
compensated reading and a non-temperature compensated 
measurement manually corrected to 25!C. If discrepancies are 
noted between the two readings, the manually corrected value 
is probably the better of the two.

Remember that specific conductance measurements in extremely 
dilute samples are difficult to make. The conductivity can 
change by a measurable amount even during the short time it 
takes to make the measurement. If you have any further 
questions on this subject contact Robert F. Middelburg of my 
staff, FTS 928-6834.



                      R. J. Pickering
                      Chief, Quality of Water Branch

Enclosure

WRD Distribution:~ A, B, S, FO, PO

Key Words: water quality, equipment, specific conductance, 
           conductivity

This memorandum does not supersede any previous memorandum.





SERVICE DEPARTMENT                                   
Yellow Springs Instrument Co., Inc....
Yellow Springs, Ohio 45387 - Phone 513-767-7241   

June 1, 1981

SUBJECT:   Model 32 Conductance Instrument; Serial Numbers 
           100 thru 252, 289, 290, 292 thru 296 and 304 thru 
           307.

DESCRIPTION
OF PROBLEM: Defective components in some instruments.

SYMPTOMS: Poor linearity, drift and instability sometimes 
          individually or combined have been observed in some 
          of the subject instruments and needs to be 
          corrected.

ACTION:   Substitute a precision resistor for the conductivity 
          cell and verify the reading as suggested in the 
          procedure section.

PROCEDURE: 1. Connect a precision resistor of 5.1 to 5.5 ohms 
              across the Model 32 cell posts. If a resistance 
              decade is used, connect it with short buss wire 
              leads and add the input resistance of the 
              decade to the resistance setting.

              NOTE: YSI Service will send you a 5.25 ohm 
                    resistor on request.

           2. Switch the Model 32 to "CONDUCTANCE" and the 
              "200 mmho" range.

           3. The correct conductance reading is figured by 
              l/R (R = precision resistor) +/- 2 mmhos the 
              range tolerance and +/- the resistor tolerance.

              EX: R = 5.25 ohms, 1%. l/R = 190.5 +/- 4 mmhos. 
              If this reading is incorrect, drifts or shifts 
              with shock, the instrument should be sent back 
              for warranty service.

CONCLUSION: Should this test fail, return the instrument to 
            YSI Service for correction.

We regret any inconvenience this may cause but we believe it 
is in your best interest to be assured your Model 32 is 
operating properly.

Sincerely,

YELLOW SPRINGS INSTRUMENT CO., INC.    YSI Service Department
                                       PO Box 279
                                       Rt. 68 South
                                       Yellow Springs, Ohio 45387

Fred McDowell
Service Manager