Dry well calibrators (also known as dry block calibrators) are the gold standard for in-situ temperature sensor verification across pharmaceutical cleanrooms, petrochemical refineries, power generation, and manufacturing plants worldwide.
1. Immersion Depth and Stem Conduction Elimination
Stem conduction error occurs when ambient heat travels along the probe sheath and cools or heats the sensing element. To eliminate this error, ensure your reference probe and sensor under test (UUT) are immersed at least 15 times the outer probe diameter plus the sensor element length (typically 120mm to 150mm depth). The DB Therion Series provides a 150mm immersion depth to completely prevent stem conduction errors.
2. Stability and Thermal Equilibration
Never take calibration readings immediately upon reaching the target set point. Always allow the dry block controller to settle for at least 10 to 15 minutes in the stable zone. High-precision instruments like the DB Therion Series maintain an active PID control loop achieving ±0.03°C stability.
3. Radial and Axial Uniformity Checks
Verify that the multi-bore insert maintains less than ±0.05°C radial variation between adjacent wells. Use a precision secondary standard PRT such as the DB Metron Series for true traceable master comparison.
4. Calculating Calibration Uncertainty
Under ISO/IEC 17025 requirements, your final expanded uncertainty budget (k=2, 95% confidence) must combine the master PRT uncertainty, dry block radial uniformity, axial gradient, stability, and UUT resolution.