Equations Useful for Placing Vessels into and out of Service

The equations presented in this section are equivalent to drawing straight lines to show the gas composition transitions. The equations are frequently easier to use and provide a more precise result than manually drawn lines.

The out-of-service fuel concentration (OSFC) is the maximum fuel concentration that just avoids the flammability zone when a vessel is being taken out of service. It is shown as point S in Figure AC-6.