Yokogawa SC42-SP24 Contacting Conductivity Sensor

Configured for high-precision electrolytic conductivity measurement in industrial liquid handling networks, the Yokogawa SC42-SP24, also cataloged as the SC42 Contacting Conductivity Sensor, provides direct physical and electrical execution of process fluid interface detection.

Suffix Breakdown & Model Matrix

The Yokogawa SC42 conductivity sensor employs a structured suffix naming structure to specify wetted material composition, process connection type, cell constant, and electrode configuration.

Hardware Specifications

Process Control & DCS Instrument Characteristics

The SC42-SP24 sensor incorporates an integrated Pt1000 RTD element designed to deliver rapid dynamic temperature signals to downstream transmitter electronics for real-time automatic temperature compensation. Operating with a defined C = 0.1 cm-1 cell constant, the dual 316L stainless steel electrodes eliminate current fringing effects through targeted PEEK dielectric isolation. The hardware integrates seamlessly into 4-20 mA HART loop protocol transmitters and FOUNDATION Fieldbus / Profibus PA networks, providing high channel-to-channel isolation to prevent ground loop noise from degrading millivolt-level electrode feedback.

Frequently Asked Questions

Q: How does the cell constant (C = 0.1 cm-1) affect transmitter excitation frequency selection?

A: A cell constant of 0.1 cm-1 is optimized for low-to-medium conductivity process fluids. Downstream transmitters apply an alternating current (AC) voltage waveform across the electrodes, adjusting frequency dynamically to minimize polarization resistance and capacitive reactance at the electrode-liquid boundary.

Q: What precautions must be observed regarding the plug-in connector during field wiring?

A: The plug-in connector interface must remain free of moisture, oil, and conductive debris during assembly. Contamination across the high-impedance connector pins will degrade signal integrity and cause erroneous temperature compensation or conductivity drift readings on the DCS controller.

Field Installation Guidelines

1. Inspect the 316L stainless steel electrode surfaces and PEEK body prior to installation. Ensure no oils or greases remain on the measuring surfaces; clean with isopropyl alcohol if necessary.
2. Thread the sensor assembly into the dedicated flow cell using standard hand-tightening torque before applying a final 1/4 turn with a open-ended wrench. Do not overtighten to prevent damaging the internal seal face.
3. Keep sensor cabling strictly separated from high-voltage AC lines, motor drives, and switching inductive loads to prevent high-frequency noise injection into the microvolt measurement circuit.
4. Ensure the cable shield is grounded at a single point within the field transmitter terminal housing, maintaining a continuous floating shield along the sensor body run.
5. Verify that the flow cell mounting orientation keeps the sensing surfaces continuously fully submerged under positive process liquid flow without entrapped air pockets.