GB/T 18691.5-2021Agricultural irrigation equipment - Irrigation valves - Part 5: Control valves (English PDF)

1 Scope

This document specifies the design requirements, performance requirements, conformity assessment, marking and packaging of control valves: The control valve is suitable for water temperature not exceeding above 60°C and the water may contain certain types and concentrations of fertilizers or chemicals commonly used in agriculture:

This document applies to hydraulically actuated irrigation control valves with a nominal size of not less than DN15: The control valve is designed to work from full

Open to fully closed anywhere: Valves can be operated directly (e:g: via a spring or diaphragm) or pilot operated (e:g: via a diaphragm)

The opening and closing parts are controlled by an adjustable pilot valve): The valve can also be used as a check valve:

2 Normative references

The contents of the following documents constitute essential provisions of this document through normative references in the text: Among them, dated citations documents, only the version corresponding to that date applies to this document; for undated references, the latest edition (including all amendments) applies to this document:

GB/T 18691:1-2021 Irrigation Valves for Agricultural Irrigation Equipment Part 1: General Requirements (ISO 9635-1:2014, IDT)

GB/T 18691:2-2021 Irrigation Valves for Agricultural Irrigation Equipment Part 2: Isolation Valves (ISO 9635-2:2014, IDT)

ISO 9644 Test method for pressure loss of irrigation valves in agricultural irrigation equipment (Agriculturalirrigationequipment-

Pressurelossesinirrigationvalves-Testmethod)

3 Terms and Definitions

The terms and definitions defined in GB/T 18691:1-2021 and the following terms and definitions apply to this document:

3:1 control valve

A valve with one or more regulating functions within a specified range:

Note: Regulation functions include flow regulation, liquid level control and pressure regulation (upstream or downstream): Valves are also used to turn irrigation systems on or off:

3:1:1 automatic control valve

A control valve (3:1) that realizes automatic control by adjusting the position of the opening and closing parts to obtain the energy of transmitting water:

3:1:2

Non-autonomouscontrolvalve

A control valve (3:1) that requires external energy to adjust the position of the opening and closing parts to achieve specific function adjustment:

3:1:3 pressure-reducing valve

Control valve (3:1) that depressurizes the higher inlet pressure to the lower outlet pressure (independent of changes in flow or inlet pressure):

3:1:4 pressure-sustaining valve

Control valve (3:1) for keeping the inlet pressure constant regardless of changes in flow or outlet pressure: […]