Why is the dew point reading unstable?

Question

Daniel Halgryn · Accepted Answer

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

Why is the dew point reading unstable?

Why is the dew point reading unstable?

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