Teledyne 4250, Installation And Operation Manual, Page: 135 / 204

4250 Flow Meter
Section 4 Options and Accessories
4-25
(which can result from extended use with a loose or
wrinkled membrane), you need to restore its surface.
You can return it to Teledyne Isco or clean it yourself
with a probe reconditioning kit. (This kit is available
from Teledyne Isco.) Never use chemicals or any
abrasive not supplied with this kit. It is also possible for
the silver anode to become contaminated, which will
prevent successful calibration. Try soaking the probe
overnight in a 3% ammonia solution; then rinse with
deionized water, recharge with electrolyte, and install a
new membrane. If you are still unable to recalibrate the
probe after several hours, return the probe to Teledyne
Isco for service.
• If the sensor O-ring is worn or loose, you should replace
it. The probe comes with a kit of O-rings and
replacement membranes. Additional replacement
O-rings are available from Teledyne Isco in an O-ring
replacement pack.
• If the probe is not going to be in constant use, you should
store it in the plastic bottle provided in shipping. To
keep the electrolyte from drying out, place a small piece
of moist towel or sponge in the bottle and insert the
probe into the open end. If you need service for your
D.O. probe, Teledyne Isco recommends returning the
unit for evaluation. In addition to servicing the probe,
we can also provide advice on product applications, and
you can also purchase other accessories for use with the
D.O. probe. Use only 2-mil membranes with D.O. probes
connected to Isco flow meters.
Table 4-4 D.O. Probe Specifications
Cathode Gold
Anode Silver
Membrane FEP Teflon; 2 mil standard
Electrolyte Half-saturated KCl (Potassium Chloride)
Temp. Range 0° to +45° C
Polarizing Voltage 0.8 Volts (Nominal)
Probe Current in Air
at 30° C 19 microamps (nominal)
Probe Current in Nitrogen
at 30° C 0.15 microamps or less
Connection 12 ft. (3.2 m) cable with 5-pin male M/S
connector
Response Time Typical response for dissolved oxygen,
using supplied membranes, is 90% in 20
seconds. Response at low dissolved oxy-
gen levels is typically 90% in 60 seconds.