YSI Professional Plus User Manual

Page 36

cap. If the cathode remains tarnished, contact YSI technical Support or the

Authorized dealer where you purchased the instrument.

Silver Anode

After extended use, a thick layer of Silver Chloride (AgCl) builds up on the

silver anode reducing the sensitivity of the sensor. the anode must be cleaned to

remove this layer and restore proper performance. the cleaning can be chemical

or mechanical:

Chemical cleaning: Remove the membrane cap and rinse the electrodes with

deionized or distilled water. Soak the sensing anode section of the sensor in

a 14% ammonium hydroxide solution for 2 to 3 minutes or in a 3% ammonia

solution overnight for 8-12 hours (most household ammonia cleaners are

typically around 3%). Rinse heavily in cool tap water followed by a thorough

rinsing with distilled or deionized water. the anode should then be thoroughly

wiped with a wet paper towel to remove the residual layer from the anode. You

can smell the tip of the sensor to help ensure all the ammonia has been rinsed off.

trapping residual ammonia under the new membrane cap can quickly tarnish

the electrode and/or give false readings.

Chemical cleaning should be performed as infrequently as possible.

First attempt a membrane change and recalibrate. If a new

membrane does not resolve the problem, then proceed with cleaning.

Mechanical cleaning: In order to sand the silver anode along the shaft of the

sensor, simply hold the sensor in a vertical position. Wet the sanding disk with

a small amount of clean water then gently wrap it around the sensor shaft and

twist it a few times to lightly sand the anode (the goal is to simply sand off any

build-up without scratching or removing layers of the anode itself). Usually, 3

to 4 twists of the sanding disk are sufficient to remove deposits. However, in

extreme cases, more sanding may be required to regenerate the original silver

surface.

After completing the sanding procedure, repeatedly rinse the electrode with

clean water and wipe with lens cleaning tissue to remove any grit left by the

sanding disk. thoroughly rinse the entire tip of the sensor with distilled or

deionized water and install a new membrane.

IMPORTANT: Be sure to: (1) Use only the fine sanding disks

provided and (2) Sand as mentioned in the above procedures.

Not adhering to either of these instructions can damage the

electrodes. If this procedure is unsuccessful, as indicated by

improper electrode performance, contact YSI Technical Support

or the Authorized dealer where you purchased the instrument.

Galvanic Sensors – Model # 605202

We recommend that the Sodium Chloride (NaCl) solution and the membrane

cap be changed at least once every 60 days during regular use. In addition, the

NaCl solution and membrane should be changed if (a) bubbles are visible under

the membrane; (b) significant deposits of dried electrolyte are visible around the

membrane; and (c) if the sensor shows unstable readings or other sensor-related

symptoms.

the Galvanic dissolved oxygen sensor is continuously reducing oxygen even

when the display of the instrument is not active. this factor allows the sensor

to be used with no warm-up period as soon as the instrument is powered on

(instant on Do). However, because the sensor is “on” all the time, some solid

from the oxidation of the zinc anode will form in the electrolyte within 1-2 weeks

of activation. Small amounts of the solid will generally cause no performance

problems, but excessive amounts may result in jumpy dissolved oxygen readings.

the rate of solid formation is dependent on the type of membrane installed. the

formation of solids based on membrane type typically form more rapidly with

the 5912 (1 mil teflon), less rapid with 5913 (1.25 mil PE), and least rapid with

5914 (2 mil PE).

The Galvanic DO sensor solution will appear milky white

after use but will NOT affect the accuracy of the sensor unless

there is excessive build up. The color change is acceptable

and normal as long as DO readings remain stable.

At the time the membrane cap is changed, YSI recommends that you rinse the

anode (silver shaft of the sensor) with purified water and wipe with a clean paper

towel. If white deposits are evident on the anode after cleaning, YSI recommends

that you remove this material by sanding the anode with the sandpaper disk

enclosed in your membrane kit. Follow the “Mechanical Cleaning” instructions

under the Polarographic Silver Anode section.

IMPORTANT: Be sure to: (1) Use only the fine sanding disks

provided and (2) Sand as mentioned in the above procedures. Not

adhering to either of these instructions can damage the electrodes.

WARNING: DO NOT PERFORM THE POLAROGRAPHIC

CHEMICAL CLEANING ON A GALVANIC SENSOR. If

this procedure is unsuccessful, as indicated by improper

electrode performance, contact YSI Technical Support or the

Authorized dealer where you purchased the instrument.