Support Center: Guides & FAQs

• The sensor may be incorrectly installed — for example, not centered or installed at the wrong depth.
• The wrong gas type, flow units, or reference conditions may be selected in the settings.
• The inner pipe diameter might be entered incorrectly in the software.
• The sensor technology may not be suitable for the current application (e.g., thermal mass sensors in very humid environments).
• There may not be enough straight pipe before or after the sensor, causing turbulent flow.

• Verify the sensor is properly centered in the pipe and installed at the recommended depth and orientation.
• Check the gas type, measurement units, and reference pressure/temperature conditions in the S4C-FS software.
• Enter the correct inner pipe diameter to ensure proper flow calculation.
• Make sure the sensor technology is appropriate for the gas conditions (e.g., avoid thermal mass sensors where liquid water may be present).
• Install the sensor with adequate straight pipe lengths before and after, as specified in the manual.

An unstable dew point reading usually means the moisture conditions at the sensor are changing or the measurement conditions are unstable. Possible causes include system instability, poor installation, contamination, or electrical interference.

Possible causes:

• Pressure fluctuations or pulsations affecting the sensor
• Unstable or insufficient sample flow
• Dead volume or poor sample line design
• Condensate, oil mist, or contamination reaching the sensor
• Rapid dryer cycling or changing process conditions
• Insufficient stabilization time after startup or humidity changes
• Electrical noise, poor grounding, or signal interference
• Faults in the analog reading device or wiring

Recommended checks:

• Verify stable pressure and flow conditions
• Inspect installation point and sample line design
• Check upstream filtration and drainage
• Inspect wiring, shielding, and grounding
• Allow enough stabilization time
• Compare with a reference instrument if necessary
• Check for electrical noise using a multimeter or oscilloscope if suspected