Industrial / Process Formulas
Industrial and process formulas convert sensor outputs, current loops, and control parameters into engineering units. These calculators help you scale 4-20mA signals and reason about loop behaviour. They are foundational to automation and instrumentation.
Industrial / Process Formula Calculators
- 4–20 mA Loop Scaling I = 4 + 16 × (val − min) / (max − min) Process Value 0.025, Range Minimum 0.055, Range Maximum 0.118 → Loop Current = -3.619 mA
- 4–20 mA Burden Voltage V_burden = I × R Loop Current 100 µA, Burden Resistance 1 Ω → Burden Voltage = 100 µV
- Thermocouple Cold Junction Compensation T_hot = T_cjc + V / S Cold Junction Temp 5.5 °C, Thermocouple Voltage 1 µV, Seebeck Coefficient 0.1 µV/°C → Hot Junction Temp = 15.5 °C
- Control Valve Flow (Cv) Q = Cv × √(ΔP / SG) Valve Cv 0.025, Pressure Drop 0.1 PSI, Specific Gravity 0.055 → Flow Rate = 0.03371 GPM
- PLC Scan Time t_total = t_io + t_logic + t_comms I/O Scan Time 0.22 ms, Logic Execution Time 0.47 ms, Communications Time 47 µs → Total Scan Time = 0.737 ms
Worked result for every Industrial / Process formula
| Formula | Expression | Worked result |
|---|---|---|
| 4–20 mA Loop Scaling | I = 4 + 16 × (val − min) / (max − min) | Process Value 0.025, Range Minimum 0.055, Range Maximum 0.118 → Loop Current = -3.619 mA |
| 4–20 mA Burden Voltage | V_burden = I × R | Loop Current 100 µA, Burden Resistance 1 Ω → Burden Voltage = 100 µV |
| Thermocouple Cold Junction Compensation | T_hot = T_cjc + V / S | Cold Junction Temp 5.5 °C, Thermocouple Voltage 1 µV, Seebeck Coefficient 0.1 µV/°C → Hot Junction Temp = 15.5 °C |
| Control Valve Flow (Cv) | Q = Cv × √(ΔP / SG) | Valve Cv 0.025, Pressure Drop 0.1 PSI, Specific Gravity 0.055 → Flow Rate = 0.03371 GPM |
| PLC Scan Time | t_total = t_io + t_logic + t_comms | I/O Scan Time 0.22 ms, Logic Execution Time 0.47 ms, Communications Time 47 µs → Total Scan Time = 0.737 ms |
Variables used across Industrial / Process formulas
- I — Loop current (mA)
- val — Current process variable value
- min — Process variable at 4 mA (range minimum)
- max — Process variable at 20 mA (range maximum)
- V — Voltage across the burden resistor (V)
- R — Burden resistance (Ω)
- T_hot — Actual temperature at the measurement point (°C)
- T_cjc — Cold junction temperature measured by a separate sensor (°C)
- S — Seebeck coefficient (µV/°C)
- Q — Volumetric flow rate (US GPM)
- Cv — Valve flow coefficient (dimensionless)
- ΔP — Pressure drop across the valve (PSI)
- SG — Specific gravity of the fluid relative to water (dimensionless)
- t_total — Total scan cycle time (s)
- t_io — Time to read inputs and write outputs (s)
- t_logic — Time to execute the user program (s)
- t_comms — Time for network communication and housekeeping (s)
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