General
Refillable	ja -

The XR42-S7 is a calomel reference electrode from manufacturer Chauvin Arnoux, specifically designed for pH and redox measurements. It serves as a reference electrode in systems with separate electrodes, where the measuring electrode detects hydrogen ion activity and the reference electrode provides a constant reference potential. The electrode features a robust body made of PVC and a porous ceramic diaphragm that allows controlled release of the reference electrolyte. The reference element consists of mercury (Hg) and mercury chloride (Hg₂Cl₂), embedded in a saturated potassium chloride solution (3 mol/l). The electrode is equipped with an S7 connector, enabling a secure connection to compatible measuring devices. It is suitable for use in laboratories and in the field, and features long-term stability and a low temperature coefficient.

Applications
The XR42-S7 is intended for pH and redox measurements in various application areas, particularly in laboratory environments and field operations. It is suitable for measurements in aqueous solutions where chloride ions do not react with components of the sample, such as silver ions (Ag⁺), as these could form AgCl precipitation. In such cases, a reference electrode based on mercury sulfate is recommended. The electrode should be used in combination with measuring electrodes such as BV41A/H or XV41 to ensure accurate pH measurement.

Functions and Equipment in Detail
The reference electrode XR42-S7 provides a stable and constant potential that serves as a reference for measurement. The reference element is housed in a PVC body, which is mechanically robust and protects the electrode from mechanical damage. The porous ceramic diaphragm enables controlled diffusion of the reference electrolyte, ensuring uniform contact with the measuring solution. The electrode is refillable, extending its service life and maintaining measurement accuracy over a longer period. The S7 connector allows for a secure and standardized connection to measuring devices that support this interface.

Technology Explained Simply
In pH measurement, the potential difference between the measuring electrode and the reference electrode is detected. The measuring electrode responds to the concentration of hydronium ions (H₃O⁺) in the solution, while the reference electrode provides a constant potential. The XR42-S7 uses the calomel system (Hg/Hg₂Cl₂), operated in a saturated KCl solution (3 mol/l). This system is known for its stability and low temperature dependence. The ceramic connection ensures uniform diffusion of the electrolyte, guaranteeing stable measurement. The electrode is designed for operating temperatures from 0 to 60 °C.

Compatibility and Accessories
The XR42-S7 is to be used in combination with measuring electrodes such as BV41A/H or XV41. Suitable accessories include the KCl 3 mol/L solution (30 mL) and the Pepsin/HCl solution (125 mL), which are suitable for maintenance and calibration of the electrode. The electrode is designed for use with devices that support an S7 connector.

Mounting and Installation
The electrode is connected to the measuring device via the S7 connector. Mounting is done by screwing the connector onto the device. The electrode should be refilled with the recommended calibration solution (KCl 3 mol/l) before first use and during regular maintenance. The ceramic connection should be kept clean to ensure optimal electrolyte diffusion. The electrode is not suitable for use in solutions containing Ag⁺ ions, as AgCl precipitation may occur.

Advantages in Operation
The XR42-S7 offers high stability of the reference potential, resulting in reproducible and reliable measurement results. The use of a PVC body increases mechanical robustness, and the refillable design extends service life. The S7 connector enables a standardized and secure connection. The electrode is suitable for use in laboratory and field applications, with an operating temperature range of 0 to 60 °C providing broad application possibilities. The low temperature dependence ensures consistent performance over a wide temperature range.