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THE CALCULATORS

First Order System Response Calculation

Calculates the thermal response time and time constant for a cylindrical probe using the lumped-capacitance model.

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1. Define Input Parameters

2. Engineering Output

Wetted Volume (V)
- m³
Wetted Surface Area (A)
- m²
Characteristic Length (Lc)
- m
Biot Number (Bi)
- dimensionless
Time Constant (tau)
- s
Response Time (tp)
- s

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Context & Assumptions

The first-order system response model characterizes the thermal lag of a sensor or mass when exposed to a step change in fluid temperature. By calculating the time constant and Biot number, engineers can verify if the lumped-capacitance assumption is valid and ensure the sensor reacts quickly enough for safety requirements.

Understand the Engineering Principles

Review the step-by-step derivations, typical industrial limits, and scale-up rules.

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