This International Standard specifies a test method for determining the pressure loss in agricultural irrigation valves under steady-state conditions when water flows through them. The scope and accuracy of the valve performance specifications presented will assist agricultural irrigation system designers in comparing pressure losses through various types of valves. The measurement of pressure losses provides a means for determining the relationship between pressure loss and flow rate through the valve. This International Standard also describes the method of reporting pertinent test data. No attempt is made to define product use, design or applications. The test method is suitable for valves with equal inlet and outlet nominal sizes. NOTE Unless otherwise specified, the equations are expressed in the SI units recommended by ISO 1000.