Replacing an electrochemical sensor should be straightforward – but one of the most common questions we receive is:

“Will this electrode work with my existing meter or process system?”

The connector is often the first thing customers check, but it’s only one part of the compatibility puzzle. Temperature compensation, cable configuration, installation thread, and electrode design can all affect whether a replacement sensor will work correctly.

This guide explains what to look for when replacing an electrode, helping you avoid costly compatibility issues and ensuring you select the right sensor first time.

Is the Connector the Only Thing That Matters?

Not quite.

Although the connector must be compatible with your instrument, it’s only one of several factors that determine whether an electrode will function correctly.
When selecting a replacement electrode, it’s worth checking:

• Connector type
• Temperature sensor (if fitted)
• Cable configuration
• Installation thread
• Electrode dimensions
• Measurement parameter (pH, ORP, conductivity, etc.)
• Measuring range (where applicable)

Matching the connector alone doesn’t always guarantee compatibility.

Common Connector Types

Different instruments are designed to accept different connector types. Below are some of the most commonly used connectors across laboratory and industrial applications.

BNC

Commonly used for: Laboratory applications across most sensor types, excluding reference electrodes.

Key features: One of the most widely used laboratory connections, BNC features a simple twist-lock design that provides a secure connection while allowing sensors to be quickly connected and disconnected.

Sentek Insight: For applications requiring additional protection, we can fit BNC connectors with a protective boot to help make the connection splash and dust resistant.

S7

Commonly used for: Laboratory, swimming pool and other non-process applications where a detachable cable is preferred.

Key features: S7 connectors allow the cable to be detached from the electrode, making sensor cleaning, storage and replacement much easier.

S8

Commonly used for: Industrial process installations requiring both a detachable cable and threaded process connection.

Key features: Like the S7, the S8 provides a detachable cable connection, but adds a PG13.5 process thread for secure installation into pipelines, flow cells and process vessels.

Sentek Insight: For easier installation, a free-turning S8 option allows the electrode to be screwed into place without twisting the cable.

VP6

Commonly used for: Industrial process applications requiring a detachable cable and integrated temperature sensing.

Key features: VP6 provides connections for both the measurement and temperature signals through a single detachable cable. It also features a free-rotating PG13.5 process thread and robust IP68-rated connection, making it well suited to demanding process environments.

K8

Commonly used for: Industrial process applications requiring a detachable cable without integrated temperature sensing.

Key features: K8 provides a detachable connection for pH, ORP and 2-pole conductivity sensors and incorporates a PG13.5 process thread for installation into pipelines and process fittings.

DIN

Commonly used for: Laboratory and industrial instruments designed around a DIN connection.

Key features: DIN connectors provide a robust electrical connection with good shielding against interference and are used across a wide range of analytical instruments.

4mm Banana

Commonly used for: Laboratory instruments, reference cells, often alongside a DIN connection where integrated temperature measurement is required.

Key features: A simple plug-in connection commonly used to carry the temperature signal separately from the main electrode connection.

2mm and 4mm Pin

Commonly used for: Reference electrodes in laboratory measurement systems.

Key features: A simple plug-in connection commonly used where a separate reference electrode is required.

CFE (Clean Finished Ends) / Open End

Commonly used for: OEM instrumentation and custom wiring applications.

Key features: CFE (Clean Finished Ends), or open-end connections, allow the electrode itself (or the detachable cable, e.g. S7 or VP6 cables) to be wired directly into an instrument, transmitter or controller rather than using a pre-fitted connector.

Connector Compatibility at a Glance

These are just some of the most common connector types we work with. There are plenty of others, so if you don’t see the connection used by your instrument, just ask – our team can help identify the right option for your setup.

For an at-a-glance comparison, here’s how the most common options differ:

Choosing a Replacement Electrode: Five Things to Check

Finding a compatible replacement is about much more than matching the connector.

1. Will it connect to your instrument?

Start by identifying the connector fitted to your existing electrode.
If you’re unsure, a photograph or the model number is often enough for our technical team to identify the correct option.

2. Does it have the correct temperature sensor?

Many modern pH systems include automatic temperature compensation (ATC).
Even if two electrodes share the same connector, they may contain different temperature elements, making them incompatible with certain instruments.
The main temperature sensor types are Pt100, Pt1000, 10K and 30K, but other options are available. If your instrument requires a different temperature sensor, just ask – we can work with you to find a compatible solution.

3. Is the installation compatible?

Think about how the electrode is installed. Do you need:

• PG13.5 thread?
• Free rotating options?
• Waterproof connections?

4. Is the cable suitable?

Cable length and construction can make a big difference. For example:

• Fixed cable or detachable?
• Shortened length or extended cable?
• Free-rotating cable?

Selecting the right cable can simplify installation and future maintenance.

5. Is the electrode designed for your application?

Even if every connection matches perfectly, the electrode still needs to suit the process.
For example:

• High-temperature applications
• High-pressure applications
• Maintenance requirements
• Robust or Single-Use
• Sample type

Choosing an electrode designed for the operating conditions will improve both performance and service life.

Sentek Technical Tip

One of the easiest ways to avoid ordering the wrong replacement electrode is simply to tell us what instrument you’re using, a little about your application, and what you’ll be measuring.
Our technical team can usually identify the correct connector, temperature sensor and cable configuration from the instrument model or your existing electrode, saving time and avoiding compatibility issues.

Not Sure Which Electrode You Need?

Replacing an electrode shouldn’t be a guessing game.

If you know your instrument model – or even better, have the part number or a photograph of your setup – our technical team can help identify a compatible sensor or replacement.

Whether you need a standard laboratory electrode, a custom cable assembly or an OEM solution, we’re happy to help you select the most appropriate option first time.