• HI1131P Refillable Single Junction Glass Combination pH Electrode Measuring range: 0 to 13 pH, Sample temperature range: 0 to 100°C (32 to 212°F), Sample pressure ≤0.1 bar; BNC+PIN connector

• Suitable for routine laboratory, beer and other sample measurements

• When using a new electrode, first remove the protective cap from the top and inspect the entire electrode. If salt crystals are found on the electrode head and inside the protective cap due to evaporation of the internal electrolyte through the junction, this does not affect normal use of the electrode and indicates that the electrode junction is functioning properly; simply rinse it off with clean water. During transport, air bubbles may form inside the glass bulb at the electrode head. In this case, gently shake the electrode as you would a common mercury thermometer to remove the bubbles. If the glass sensing membrane or junction of the electrode is relatively dry, soak the electrode in HI70300 electrode storage solution for at least 1 hour to keep the dry glass sensing membrane and junction moist; frequent soaking is beneficial for the electrode.

HI1131P features high-temperature (HT) glass, spherical bulb, glass body, single ceramic frit, double junction, refillable with 3.5M KCl.

High-Temperature Glass Formulation

Measuring pH at very high temperatures is harmful to sensitive glass bulbs and shortens their service life. pH electrodes with general-purpose (GP) glass have a resistance of 100 megohms at 25°C, while HT glass has a resistance of approximately 400 megohms at 25°C. Since HI1131P is used at high temperatures, the resistance decreases to approach that of GP glass. HI1131P is suitable for sample measurement ranges of 0 to 100°C.

Spherical Glass Tip

Spherical bulbs are used for general purposes. Other shapes include conical for penetration and flat for surface measurements.

Glass Body

A glass body is ideal for laboratory use. The glass resists many harsh chemicals and is easy to clean. The glass body also allows heat to be transferred quickly to the internal reference electrolyte. The mV generated by the reference cell is temperature-dependent. The faster the electrode reaches equilibrium, the more stable the reference potential.

Single Ceramic Double Junction Reference

HI1131P features a double junction design. pH electrodes are available with either single or double junctions. For a complete explanation of the differences, please refer to the section below. The junction, also called a salt bridge, is an essential component of the circuit. Ion movement must flow through the junction to obtain stable readings. The outer reference has a single ceramic frit. Ceramic is a porous material that fuses easily with the glass body and has a similar coefficient of expansion. The flow rate of a single ceramic junction is 15-20 μL/hour. Other junction types have higher flow rates and are made from different materials.

Refillable

HI1131P is a refillable probe. Since it is a double junction pH electrode, the filling solution is HI7082 3.5M KCl. This solution does not contain any silver, unlike single junction electrodes. The absence of silver prevents any silver precipitate from forming at the junction and clogging it. A clogged junction will cause reading drift and instability.  

BNC + Pin Connector

• HI1131P uses a BNC and pin connector. The BNC connector is universal, as it can be used with any pH meter that has a female BNC probe input. The pin connector is used to enable the CAL Check function on the following benchtop pH meters: HI122, HI123, HI221, HI222, HI223, HI2221, HI2222 and HI2223.

• Note: Do not use distilled or deionized water to store or soak the electrode, as this will cause the electrode sensor to fail