A method of calibrating individual exit lines of an agricultural ammonia applicator having a delivery path that extends through a manifold and multiple exit lines includes installing a fixed flow restricting orifice upstream of a variable flow restricting orifice and measuring the pressure upstream of the fixed flow restricting orifice. Beginning with the variable flow restricting orifice in an unrestricting flow condition, the pressure downstream of the variable flow restricting orifice is repeatedly measured and compared with the measured upstream pressure. The variable flow restricting orifice is incrementally closed after each comparison so long as the measured pressure downstream of the variable flow restricting orifice and the pressure upstream of the fixed flow restricting orifice remain substantially the same. The variable orifice maximum flow setting is recorded when the measured pressure downstream of the variable flow restricting orifice drops below the pressure upstream of the fixed flow restricting orifice.
