Use of emitter coefficients instead of directly specifying flow rate enable the discharge during flushing to be sensitive to pressure in the distribution system. Some typical values for hydrants found in North America are given in the table below. In other areas with different hydrants, users are encouraged to calibrate their local hydrants.

See page 453 of Advanced Water distribution Modeling and Management (Bentley) for additional background. Do not specify both an emitter coefficient and a flow.