ISEmax CAS40D

Summary

Product Identification

Product Name: ISEmax CAS40D Product Type: Ion-selective sensor for continuous measurement of ammonium, nitrate, and other ions. Application: Online measurement of nutrient parameters in municipal wastewater treatment plants.

Function and System Design

Measuring Principle

The sensor utilizes an ion-selective electrode (ISE) with a membrane containing an ionophore. This membrane facilitates the selective migration of specific ions (e.g., ammonium or nitrate) to the electrode, creating a potential proportional to the logarithm of the ion concentration. This potential is measured against a reference electrode and converted to concentration using the Nernst equation. Color and turbidity do not affect the measurement.

Interference

Potential measurement errors can occur due to interference ions.

• Potassium (K⁺) can cause higher measured values when measuring ammonium due to chemical similarity.
• Chloride (Cl⁻) can cause higher measured values when measuring nitrate. To mitigate these errors, optional electrodes can be used to measure and compensate for potassium or chloride concentrations.

Measuring System Components

A complete measuring system typically includes:

• Sensor CAS40D
• Ion-selective electrode(s) for ammonium, nitrate, potassium, or chloride
• pH glass electrode (Orbisint CPS11-1AS2GSA)
• Temperature sensor (CTS1)
• Transmitter (Liquiline CM44x)
• Optional: Assembly holder, weather protection cover, compressed air generator.

Input Parameters

Measured Values

Depending on the sensor version, the following can be measured:

• Ammonium (NH₄-N, NH₄⁺) in mg/l
• Nitrate (NO₃-N, NO₃⁻) in mg/l
• Potassium (K⁺) in mg/l
• Chloride (Cl⁻) in mg/l
• pH value
• Temperature

Measuring Ranges

• Ammonium: 0.1 to 1000 mg/l (NH₄-N)
• Nitrate: 0.1 to 1000 mg/l (NO₃-N)
• Potassium: 1 to 1000 mg/l
• Chloride: 1 to 1000 mg/l

Electrical Connection

• Options: M12 connector or fixed cable with ferrules for connection to Liquiline CM44x transmitter.
• Maximum Cable Length: 100 m (328 ft).

Performance Characteristics

• Response Time (t90) of Ion-Selective Sensors: < 2 min (for a change between 0.5 and 1 mmol/l at 25 °C).
• Measured Error: ± 5 % of the measured value ± 0.2 mg/l.
• Repeatability: ± 3 % of the display value.
• Compensation:
  • Ammonium: Temperature (2-40 °C), pH (5-8.3 without compensation, 5-10 with compensation), Potassium (1-1000 mg/l).
  • Nitrate: Temperature (2-40 °C), pH (2-12), Chloride (10-1000 mg/l).
  • Potassium: Temperature (2-40 °C), pH (2-12).
  • Chloride: Temperature (2-40 °C), pH (1-10).

Maintenance and Durability

• Max. Operating Life (Membrane and Electrolyte): Approximately 0.5 years in use, 2 years in storage.
• Automatic Cleaning:
  • Medium: Compressed Air
  • Pressure: 3 to 3.5 bar (45 to 50 psi)
  • Volume per Cycle: 3 to 4 l (0.8 to 1 US gal)
  • Duration per Cycle: 4 to 15 s
  • Intervals (at T > 10 °C):
    • Sludge activation inlet: 15 s cleaning, 30 min pause.
    • Sludge activation: 15 s cleaning, 1 hr pause.

Environmental and Process Limits

• Ambient Temperature: –20 to 50 °C (–4 to 122 °F).
• Storage Temperature: 2 to 40 °C (36 to 104 °F).
• Degree of Protection: IP68.
• Electromagnetic Compatibility: As per EN 61 326, Namur NE21.
• Process Temperature: 2 to 40 °C (36 to 104 °F).
• Process Pressure: Max. 400 mbar overpressure.
• pH Value of Medium:
  • Ammonium: pH 5 to 8.3 (without compensation), pH 5 to 10 (with compensation).
  • Nitrate, Potassium: pH 2 to 12.
  • Chloride: pH 1 to 10.

Mechanical Construction

• Dimensions: See diagram on page 6 for detailed dimensions in mm (inch).
• Weight: Approx. 3.5 kg (7.7 lbs).

Materials

• Sensor Body: POM
• Protective Cage: POM
• Electrode Holder: Silicone
• Radial Seal: EPDM
• O-rings (ISE holder): VITON
• O-rings (air nozzle): PP
• Sensor Pipe: Stainless steel
• Sensor Head: Glass
• Ion-Selective Electrodes (Membrane Cap): POM
• Ion-Selective Electrodes (Shaft): POM
• Ion-Selective Electrodes (Membrane): PVC, plasticizer

Compressed Air Cleaning Unit

• Operating Interval: Max. 3 minutes cleaning, with a break at least six times the cleaning duration.
• Power Supply Options: 230 V or 115 V.
• Conveying Rate (atmospheric pressure): 50 l/min (13.2 gal/min).
• Power Consumption: 240 W.
• Current Consumption: 1.3 A.

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Disclaimer: This extraction may miss figures, footnotes, or revisions. Contractual data must match the OEM PDF revision used on the project.

Official datasheet (PDF)

Lenntech datasheet mirror