Teledyne 4250, Installation And Operation Manual, Page: 128 / 204

4250 Flow Meter
Section 4 Options and Accessories
4-18
When you have entered this second value, the pH probe
calibration is complete. You can then install the probe in
the flow stream.
Note
An asterisk (*) may occasionally appear next to the pH reading
for approximately 30 seconds, during which time the most
recent reading will be displayed. This may be normal flow
meter operation due to other internal functions, or could inicate
pH fluctuation in the stream.
4.10.2 pH Probe Installation
Guidelines
Installation of the pH probe is similar to the submerged level
sensor and other parameter probes.
• Install the probe only in streams that have continuous
flow. The sensing end of the probe must always remain
wet.
• For proper operation, there must also be enough flow to
submerge the sensing end of the probe completely.
If flow in the stream is intermittent (dry for periods of time), the
pH sensing bulb will dry out and its response time will slow. This
is a problem in situations where pH changes rapidly. If the probe
is dry long enough, it will first lose sensitivity, then be slow to
respond, and finally stop working. Never let the sensing end of
the probe dry out completely.
• Installation in streams with high grease content will
result in poor performance and require frequent
cleaning and recalibration.
Greasy substances, being nonconductors of electricity, weaken
the electrical potentials formed between the glass mono-electrode
and the solution, slowing or halting the response altogether.
The pH Sensor operates satisfactorily mounted either horizon-
tally or vertically in the stream. However, horizontal mounting is
more secure, and presents less of a debris trap.
• Simple suspension of the probe is not recommended,
particularly in streams of high velocity, or those that
carry debris.
If you mount the pH probe vertically, mount it securely. Do not
just hang it from the top of the pipe by its cable. Suspending the
probe in the stream is not stable.
For horizontal mounting, the probe fastens to a sensor carrier
that snap-fits to an Isco mounting ring. The mounting rings fit
various diameters of round pipes 15" diameter and smaller. For
larger pipes, use the
Isco Universal Mounting Ring . For
installation details, refer to the instruction sheet supplied with
the mounting ring.
RINSE PROBE AND PLACE IN 7.0 pH SOLUTION
PRESS ENTER WHEN STABLE:
X.XX pH