Is the summation of integrated demand and the controlled demand.
This generally represents the maximum potential system flow, which must conform to actual measured mass flow levels.
The instantaneous demand is not generally maintained for extended time durations.
The instantaneous demand often represents the driving parameter used to size and operate the supply system.
Instantaneous demand is often characterized by decreasing system pressure. Compressors are often operated to over power this demands spike and to prevent the decreasing pressure event(s).
Instantaneous demand generally defines the maximum flow that must be replenished with installed compressor horsepower. It is a reliable number, even though it may be a transient condition and represents a portion of total system uptime. The compressor(s) operating in a trim position will often be started in response to instantaneous demand and will continue to operate at minimal drive efficiencies consuming power without performing any a productive work.
Instantaneous demands can impose additional non productive support requirements of 50% or more than the power requirements of the productive demands. (099)