GB/T 21402-2008 in English

《GB/T 21402-2008农业灌溉设备 水头控制器》由TC201（全国农业机械标准化技术委员会）归口，TC201SC4（全国农业机械标准化技术委员会排灌设备和系统分会）执行，主管部门为中国机械工业联合会。
本标准规定了压力灌溉系统中水头控制器的零部件要求以及安装方法。本标准仅适用于喷灌和微灌（小型喷灌、滴灌等）系统中水头控制器的地上零部件。也可适用于一般性的灌溉水头控制器。在一般性的灌溉水头控制器上可安装其他的灌溉控制和指令元件（例电气、电子、水力），但不能用于额外元件。本标准不适用于系统和／或元件中的灌溉水头控制器有防冻要求的情况，例如干筒式水栓或其他形式的水栓。

Scope

This standard specifies the parts requirements and installation method of the water head controller in the pressure irrigation system (referred to as the irrigation head controller, and its standard size is not more than 200mm). This standard is only applicable to above-ground components of water head controllers in sprinkler irrigation and micro-irrigation (small sprinkler irrigation, drip irrigation, etc.) systems. Also applicable to general irrigation head controllers. Additional irrigation control and command components (e.g. electrical, electronic, hydraulic) may be mounted on a generic irrigation head controller, but not for additional components. This standard does not apply where frost protection is required for irrigation head controls in systems and/or components such as dry cylinder hydrants or other forms of hydrants. This standard does not give a description of the special design and operation requirements of the individual components that make up the irrigation head controller, and details are given in their respective relevant standards. Irrigation head controllers for systems incorporating pesticide spraying components shall have backflow prevention elements and spray detection valves and other safety equipment (as required by local codes and regulations), but such equipment is not covered by this standard.