Apera LabSen 251 Non-Refillable Spear pH Electrode for Solid Samples

Product Overview

The Apera LabSen 251 is a professional non-refillable spear-type pH electrode designed for direct pH measurement of semi-solid and solid samples. Featuring Apera’s proprietary Swiss sensor technology and premium materials, the electrode is engineered for fast response, high mechanical strength, and reliable measurement performance in challenging sample matrices.

Its specialized LabSen S-type spear glass membrane provides low resistance and high firmness, allowing the electrode to penetrate semi-solid samples while minimizing the risk of accidental membrane damage. The open and ceramic double-junction design with polymer electrolyte provides effective sample contact and reduces the possibility of junction clogging.

Key Features

• Designed for direct pH measurement of semi-solid and solid samples.
• Spear-shaped sensor enables direct penetration into sample materials.
• Ideal for foods, semi-solid materials, and other samples requiring penetration measurement.
• LabSen S-type glass membrane provides fast response and high firmness.
• Low-resistance glass membrane enables stable readings in approximately 15–30 seconds.
• Spear glass membrane is approximately 10 times stronger than traditional glass membranes.
• Highly resistant to general impact and accidental breakage during insertion.
• Open & Ceramic double-junction design provides effective contact with test samples.
• Polymer electrolyte eliminates the need for electrolyte refilling.
• Long-Life Reference System improves reference stability and extends electrode service life.
• Standard BNC connector provides compatibility with pH meters using BNC inputs.
• No built-in temperature sensor.
• External temperature probe can be used for automatic temperature compensation (ATC).

Technical Specifications

pH Measurement

• pH Range: 0–14 pH
• Sensor Type: Spear-type pH electrode
• Membrane Type: LabSen S-type glass
• Membrane Shape: Spear
• Membrane Impedance: <250 MΩ
• Typical Stabilization Time: 15–30 seconds

Temperature

• Temperature Range: 0–80°C (32–176°F)
• Temperature Sensor: No built-in temperature sensor
• Temperature Compensation: Manual temperature input or external temperature probe for ATC

Reference System

• Reference Type: Long-Life Reference System
• Junction: Ceramic + Single Pore / Open & Ceramic Double-Junction
• Electrolyte: Polymer
• Refillable: No
• Reference Construction: Glass tube, AgCl, and reference silver wire

Physical Specifications

• Housing Material: Lead-free glass
• Membrane Shape: Spear
• Length: 100 mm
• Diameter: 12–6 mm
• Connector: BNC
• Cable Length: 3 ft

Long-Life Reference System

The LabSen 251 uses a specialized Long-Life Reference System consisting of a glass tube, AgCl, and reference silver wire. The upper section of the slim glass tube is filled with cotton to help prevent unwanted reactions between AgCl and the electrolyte caused by temperature changes.

This design enhances reference stability and helps extend the electrode’s operating life.

Temperature Compensation

The LabSen 251 does not have a built-in temperature sensor. For automatic temperature compensation, an external temperature probe such as the Apera MP500 can be used with compatible meters. Alternatively, the sample temperature can be measured separately and manually entered into the pH meter.

Applications

The spear-shaped design makes the LabSen 251 particularly suitable for:

• Semi-solid samples
• Solid samples
• Food products
• Meat and meat products
• Cheese and dairy products
• Fruits and vegetables
• Soil and agricultural samples
• Cosmetics and creams
• Pharmaceutical formulations
• Other samples requiring direct penetration pH measurement

Compatibility

• Standard BNC connector.
• Compatible with pH meters equipped with a BNC electrode input.
• External temperature probe required when automatic temperature compensation is needed.

Summary

The Apera LabSen 251 Non-Refillable Spear pH Electrode is a durable and specialized electrode for direct pH testing of solid and semi-solid samples. Its reinforced LabSen S-type spear glass membrane, open & ceramic junction, polymer electrolyte, and Long-Life Reference System provide fast, stable, and reliable measurements while reducing maintenance requirements. With a standard BNC connector, it is suitable for use with a wide range of compatible pH meters in laboratory, food, agricultural, pharmaceutical, and industrial applications.