Figures given on flowsheets to indicate quantities passing various points in plant per unit time, taking account of fluctuations in the rate of supply and composition (as to size and content of impurity), as follows: (1) design capacity, the rate of feed, defined by limits expressing the extent and duration of load variations, at which specific items of plant subject to a performance guarantee must operate continuously and give the guaranteed results on a particular quality of feed; (2) peak design capacity, a rate of feed in excess of the design capacity, which specific items of plant will accept for short periods without fulfilling the performance guarantees given in respect of them; and (3) mechanical maximum capacity, the highest rate of feed at which specific items of equipment, not subject to performance guarantees, will function on the type and quality of feed for which they are supplied.