This part of ISO 13693 specifies the construction and performance requirement and test methods for metal-bodied chemigation valves with water at temperatures not exceeding 50 °C, which might contain fertilizers and chemicals of the types and concentration used in agriculture. The valve is designed to prohibit backflow caused by either back pressure or back siphonage. It is not designed for use in potable water systems. It is not to be confused with other forms of backflow prevention devices including pressure vacuum breakers, double check valves, reduced pressure zone valves, or goose neck loops. This part of ISO 13693 specifies the minimum design, construction, and performance testing requirements for the chemigation valve assembly. The assembly consists of the following components: — a valve body into which a spring-loaded check valve is mounted with a resilient disk cover on the sealing surface; — a combination air release/vacuum relief valve located upstream of the check valve; — a low pressure drain valve located upstream of the check valve; — an inspection port located so as to permit visual and manual inspection of the valve working components.