User Manual

Optical pH Sensors | User Manual

6.2 Explanation of the Different pH Ranges

Optical pH sensors are sensitive to a pH range of 2-3 pH units. Sensors are offered for

two different ranges for pH measurements.

pH range

Item No.

4.0-6.0

…-PK5

5.0-7.0

…-PK6

5.5-7.5

…-PK6.5

6.0-8.0

…-PK7

7.0-9.0

…-PK8

7.0-9.0 on pH total

scale for seawater

measurements

…-PK8T

Depending on the application it is important to choose the right version.

Calibration of both versions is performed at low pH values (completely protonated

indicator dye) and at high pH values (completely de-protonated indicator dye). For this

reason, it is possible to use the same pH buffer capsules (PHCAL2 and PHCAL11) for

both pH sensor versions.