Product Description

The HI1131P is a glass body, refillable, double junction pH electrode with a BNC and pin connector. The pin connector is used to enable the CAL Check function of the HI2221, HI2222, and HI2223 benchtop meters.  This electrode has a single ceramic junction in the outer reference cell and the spherical pH sensing portion is made with high temperature glass. This design consideration is ideal for laboratory samples, liquid samples, and high temperature samples, as well as general purpose use.

• Refillable Electrode
• Double Junction Design
• High Temperature (HT) Glass

High-Temperature Glass Formulation

The measurement of pH at very high temperatures is detrimental to the sensitive glass bulb and will shorten the life of it. A pH electrode with general-purpose (GP) glass will have a resistance of 100 megaohms at 25^oC while the resistance of HT glass is around 400 megaohms at 25^oC. As the HI1131P is used at elevated temperatures the resistance decreases to approach the that of GP glass. The HI1131P is suitable to use with samples that measure from 0 to 100^oC.

Spherical Glass Tip

The spherical bulb is for general purpose use. Other tip shapes include conic for penetration and flat tip for surface measurements.

Glass Body

The glass body is ideal for laboratory use. The glass is resistant to many harsh chemicals and is easily cleaned. The glass body also allows for a fast transfer of heat to the internal reference electrolyte. The mV generated by the reference cell is temperature-dependent. The faster the electrode reaches equilibrium, the steadier the reference potential.

Single Ceramic Double Junction Reference

The HI1131P is a double junction design. pH electrodes are available as single junction or double junction. See below for a complete description of the differences. The junction also known as a salt bridge is a necessary component of the electrical circuit. The movement of ions must flow through the junction for a steady reading. The outer reference has a single ceramic frit. The ceramic is a porous material that is easily fused with the glass body and has a similar expansion coefficient. A single ceramic junction has a flow rate of 15-20 μL/hour. Other junction types are available with higher flow rates and made with different materials.

Refillable

The HI1131P is a refillable probe. Since it is a double junction pH electrode the fill solution is the HI7082 3.5M KCl. This solution does not contain any silver as with single-junction electrode. The absence of silver will prevent any silver precipitate from forming at the junction surface and clogging it. Clogging of the junction will result in drifty and erratic readings.

BNC + Pin Connector

The HI1131P uses a BNC and pin connector. The BNC connector is universal in that it can be used on any pH meter that has the 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.