Stem Conduction Error Calculations & Thermowell Immersion Length in Industrial Piping

Stem conduction is the single largest source of systematic error in industrial temperature measurement, frequently introducing errors of 2C to 10C in high-velocity steam lines.

1. The 10D + Sensor Length Rule

For gas and vapor streams, minimum immersion depth L = 10 x outer diameter (OD) + sensitive element length. For liquids, L = 5 x OD + element length.

2. Insulating Dry Block Calibration Heads

When using dry blocks like the DB Therion, utilize top insulation collars to prevent ambient drafts from cooling the exposed probe stem.