Error Messages - Hanna Instruments HI6421 Instruction Manual

61
Membrane Cap Replacement
New probe: unscrew the shipping cap and save.
Probe in use: unscrew the old cap.
1. Take one O‑ring and one membrane cap and position the O‑ring (1) in the cap (2).
2. Rinse the membrane cap with electrolyte and discard.
3. Fill the cap, above the O‑ring, with electrolyte and tap the side walls to dislodge bubbles
that may adhere to the threads.
4. Over a sink, with the cathode facing down, screw the cap counter clockwise until the threads
are fully engaged.
5. Rinse the probe and inspect the membrane for trapped bubbles. If any, discard the electrolyte,
refill, and tap the sides. Reinstall.
Storage
Store with protective cap on.
Conditioning
Before proceeding with the calibration make sure the probe is ready for measurements.
1. Reinstall the plastic protective cap over membrane end.
2. Reconnect probe to meter and allow probe to polarize.

14. ERROR MESSAGES

The instrument shows clear warning messages (refer to the instrument's on‑display message area, bottom of
the screen) when erroneous conditions appear, and when measured values are outside the expected range.
The information below provides an explanation of the errors and warnings, and recommended action to be taken.
Displayed Message
DO over range
Temperature under / over range
Pressure under / over range
Factory calibration expired
User calibration expired
®
opdo Cap Expired
Explanation & Recommended Action
Reading is over specified measurement range i.e.
• Optical probe: above 500 % / 90 ppm (mg/L)
• Polarographic probe: above 300 % / 45 ppm (mg/L)
Ensure the sample is within specified range.
Temperature outside specified range.
• Optical probe: below –5 °C (23 °F) / above 50 °C (122 °F)
• Polarographic probe: below 0 °C (32 °F) / above 50 °C (122 °F)
Consider probe replacement if necessary.
Below 450.0 mmHg / above 850.0 mmHg (or equivalent)
DO and temperature calibration date older than 1 year
®
Contact Hanna technical support for the periodic factory calibration.
Calibrate the meter.
Replace the cap.
Error Messages
1
2
SCREW BACK