PLC analog input scaling: raw counts, 4–20 mA and diagnostics
Map raw counts into engineering units, check the configured channel range, and keep signal-quality diagnostics separate from the displayed value.
Free-air delivery
Compressor air flow expressed at stated inlet or reference conditions rather than compressed pipe-volume conditions.
Always retain the reference temperature and pressure with an air-flow number. A volume flow measured at line pressure cannot be substituted directly for a free-air flow. Match the flow basis to the specific-power data used in an energy assessment. The leak-cost guide explains the calculation boundary.
See also: Compressor specific power
Use the concept: Compressed air leak cost calculator · 4–20 mA loop scaling · Engineering unit converter
In depth
Motor kW, current, efficiency and power factor: keep the quantities straight
A three-phase example distinguishes shaft output, real input power, apparent power and running current, with the limits of a simple estimate.
Compressed air leak cost: turn flow estimates into verified savings
Calculate a leak energy equivalent, keep free-air reference conditions consistent, and check compressor response before promising a saving.