Overall Reaction Rate based on Volume of Contactor refers to the Rate Calculated when Unit Volume of Contactor is Considered. And is denoted by r''''A . Overall Reaction Rate based on Volume of Contactor is usually measured using the Mole per Cubic Meter Second for Reaction Rate. Note that the value of Overall Reaction Rate based on Volume of Contactor is always negative. Typically, the value of Overall Reaction Rate based on Volume of Contactor is greater than -999.