This part of ISO 19973 provides test procedures for assessing the reliability of the following types of pneumatic valves:— non-return (check) valves;— pilot-operated non-return valves;— shuttle valves;— dual pressure valves (AND function);— one-way adjustable flow control valves;— quick-exhaust valvesby testing and the methods of reporting the results of testing. General test conditions and the calculation method are provided in ISO 19973-1. The methods specified in ISO 19973-1 apply to the first failure, as obtained with the three-points moving average (3PMA) method, without repairs, but excluding outliers.The lifetime of these pneumatic valves is usually given as a number of cycles. Therefore, whenever the term “time” is used in this part of ISO 19973, this variable is understood as a number of cycles.This part of ISO 19973 also specifies test equipment and threshold levels for tests to assess the reliability of these pneumatic valves.