Annual air loss is computed by multiplying the estimated leak rate by the annual system operating time and a minutes-per-hour conversion factor, then dividing by the scf-to-kscf conversion factor. The factor of 60 converts operating hours to minutes so the units are consistent with the flow rate expressed in scfm. The factor of 1000 converts standard cubic feet to kiloscf, which is the conventional unit for annual compressed air volumes in industrial energy assessments.

\begin{equation}\label{eq:estimate-method-annual-consumption} C_{annual} = \frac{\dot{Q}_{leak} \cdot t_{op} \cdot 60}{1000} \end{equation}

Symbols

\(C_{annual}\)	Estimated annual air loss from the leak \([\unit{ \kscf}]\)
\(\dot{Q}_{leak}\)	Estimated compressed air leak flow rate \([\unit{ \scfm}]\)
\(t_{op}\)	Annual system operating time \([\unit{ \hour}]\)
\(60\)	Minutes per hour conversion \([\unit{ \minute\per\hour}]\)
\(1000\)	Standard cubic feet per kiloscf conversion \([\unit{ \unitless}]\)

Note

The result is in kiloscf (kscf), where 1 kscf = 1000 standard cubic feet. This unit is conventional for annual compressed air volumes in industrial energy assessments.