Manual

B. Calibration Tracking Records for General Use (Not Dialysate)

To minimize your calibration effort, keep records. If adjustments you

are making are minimal for your application, you can check less often.

Changes in conductivity calibration should be recorded in percent.

Changes in pH calibration (D-6) are best recorded in pH units.

Calibration is purposely limited in the Dialysate Meter to

10% for the

conductivity cell, as any change beyond that indicates damage, not

drift. Likewise, calibration changes are limited to

1 pH unit, as any

change beyond that indicates the end of the sensor’s lifetime and

replacement is recommended.

WARNING: For Dialysate measurements, it is critical that you verify that

the pH sensor is working at the beginning and end of each workday

or more often if required by your clinic’s internal procedures.

C. Conductivity, RES, TDS Practices to Maintain Calibration

Note: Very active chemicals may discolor the conductivity electrodes

(though this is not likely in clinical use).

• Thisdoesnotaffecttheaccuracyofconductivitymeasurements.

1. Cleanoilylmsororganicmaterialfromthecellelectrodesby

pouring isopropyl alcohol or squirting a foaming non-abrasive

cleaner into the cell and rinsing (see Cleaning Sensors, pg. 34).

• DO NOT scrub inside the cell.

2. Calibrate with solutions close to the measurements you make.

Readings are compensated for temperature based on solution

type. If you choose a solution type that does not closely match

the characteristics of the solution you are trying to measure, your

 recordsofcalibrationchangeswillreecttemperaturechanges

more than changes in the instrument’s accuracy. For example,

if you choose to measure tap water solute concentration in KCl

mode, but you calibrate with 442 because it is handy, the further

away from 25ºC the tap water sample is, the more error there

will be in the temperature-compensated reading.

Note: Dialysate

conductivity measurements MUST be set to NaCl.

3. Rinse out the cell with pure water after taking measurements.

• Allowingslowdissolvingcrystalstoforminthecell

contaminates future samples.

4. For maximum accuracy, keep the pH sensor cap on tight so that

 nouidinthepHsensorwellwashesintotheconductivitycell.

D. pH and ORP Practices to Maintain Calibration (D-6)

1. ALWAYS keep the sensor wet with Myron L pH Sensor

Storage Solution when not in use. If the pH/ORP sensor is

 allowedtodryout,itsaccuracywillbesignicantly

compromised.