For minimum flow (e.g. cfm), we look sample data where the equipment was in a loaded state. If we did not do this, we would likely always return '0' for minimum flow on the assumption that a compressor is likely to stop at some point during the audit!
Whereas 'Average flow' is just 'average flow' (it it includes '0'). Consequently 'average flow' can be smaller than minimum flow in Chart Wizard.