Section 5 – Sensor Calibration
27
5.2 pH
Calibration
Before attempting a pH calibration ensure that Temperature has been correctly calibrated (see
section 5.1). A “
∗
” in the Temperature readout in place of the decimal point indicates that
Temperature is NOT calibrated.
5.2.1 pH Calibration Procedure
1. Switch the pool pump OFF with the Pump Timer function (see section 3.6), and unplug it from
the
POOL PUMP
socket.
Remove the pH and ORP/Temperature sensors from their Tee fittings. For installations where
this fitting is below the level of the pool, 6.5mm (1/4”) and 12.5mm (1/2”) bungs can be fitted to
stop the water flow.
2. Press
the button to place the
easyCHEM 770
into Standby mode.
3. Plug the pH sensor into the
pH Probe
socket and the ORP/Temperature sensor into the
ORP
Probe
socket (if not already connected).
4. Remove the wetting cap from the pH sensor. Rinse both sensors in distilled water. Shake off
as much water as possible. Blot the outside of the sensors dry.
5. Place the pH sensor into a small sample of pH7.00 buffer. Ensure that the entire bulb and
reference junction are immersed, as per the diagram below. Place the ORP/Temperature
sensor into a separate beaker of liquid that is at the same temperature as the buffer (this is
required for correct Temperature compensation). The ORP/Temperature sensor should be
immersed to approximately 20mm above the plastic tip.
DO NOT place sensors directly into buffer bottles.
6. Select pH Calibration. (Press
, select ‘
→
Calibrate
’, then select ‘
→
Cal pH
’.)
The 7pH Calibration screen is now displayed. For example…
pH7 Calibration
7.00pH Enter
Press
when the pH reading on the bottom line becomes totally stable.
