endress+hauser Analog conductivity sensor Condumax CLS13

What it is

• The CLS13 is a conductive (2-electrode) conductivity sensor designed for measuring the electrical conductivity of liquids, especially very low conductivities (i.e., highly purified water / steam condensate) under high temperature and high pressure conditions.
• It is an analog sensor (i.e., the sensor part provides a signal to a transmitter) rather than a fully digital probe.
• It comes in different versions (cell constants, materials, explosion‐proof approvals) to suit specific applications.

Key Specifications & Features

Here are some of the major specs and features of the CLS13:

• Measuring ranges (depending on version):
• Cell constant k=0.01k = 0.01k=0.01 cm⁻¹: 0.04 … 20 µS/cm (for ultra-pure water)
• Cell constant k=0.1k = 0.1k=0.1 cm⁻¹: 0.1 … 200 µS/cm
• Process temperature: Up to approx. 250 °C (482 °F)
• Process pressure: Up to approx. 40 bar (≈580 psi) in many versions.
• Materials & construction:
• Electrodes: stainless steel (material 1.4571 / AISI 316Ti in many cases)
• Seals: Kalrez, ceramic depending on version.
• Integration of a Pt100 temperature sensor for temperature compensation – this helps correct the conductivity reading for temperature effects.
• Design features:
• Coaxially arranged electrodes (inner electrode and outer electrode) to enable accurate measurements in difficult conditions.
• Robust, durable for high-stress environments (high T, high P, maybe steam).
• Versions with explosion protection: ATEX, FM, CSA etc for hazardous areas.
• Installation/connection:
• Usually connected via a dedicated transmitter (E+H transmitter) + a special measuring cable for the analog sensor.
• Requires that the electrodes are completely immersed and wetted by the liquid (for accurate measurement) and that minimum immersion depth is observed (for example ≥50 mm).

Typical Applications

The CLS13 is designed for demanding industrial use, especially in power & energy or steam/water cycles. Examples:

• Monitoring condensate in a steam system.
• Monitoring boiler feed-water conductivity.
• Controlling boiler blow-down (i.e., monitoring when water conductivity rises and you need to purge).
• Any application where the conductivity is very low (i.e., ultra-pure or de-ionised water) but the process conditions are harsh (high temperature, high pressure, possibly steam).

Why Choose it / What Are the Benefits

• Accuracy and reliability even at low conductivities (which can be tricky because the signal is very small).
• Capable of withstanding harsh process conditions: high temperature, high pressure. (As mentioned above.)
• Easy to maintain: the outer electrode is removable, stainless steel body for cleaning.
• A quality certificate with the individual cell constant is supplied (so you know exactly the geometry/calibration of the sensor).
• Suitable for hazardous areas (explosion prone) in some versions.

Things to Watch / Considerations

• Being an analog sensor, you’ll need a compatible transmitter to convert the sensor output into a usable signal (4-20 mA or similar). It’s not a standalone digital/transmitter unit.
• Installation matters: the electrode must be fully immersed and flow/conditions must ensure proper wetting – if there’s air pockets or poor wetting, accuracy will suffer. For ultra-pure water applications, air (or dissolved CO₂) can notably affect low conductivity readings.
• Temperature compensation is integrated, but the system/ transmitter must support and use that for correct readings.
• For ultra-pure water, even minor contamination or ingress of CO₂ can alter readings significantly. The documentation warns about this.
• Maintenance/corrosion of electrodes and seals over time – given the harsh conditions, it's wise to check the sensor periodically in heavy duty installations.
• Check the exact version/part number: materials, approvals, cell constant, process connection, etc all vary.