GB/T 18691.2-2021Agricultural irrigation equipment - Irrigation valves - Part 2: Isolating valves (English PDF)

1 Scope

This document specifies the design requirements, performance requirements, conformity assessment, marking and packaging of isolation valves: The isolation 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 irrigation isolation valves with a nominal size of not less than DN8: The design working states of the isolation valve are fully open and fully closed, but also

It can work for a long time in any intermediate state:

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)

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

Through valve clearwayvalve

A valve designed with a non-clogging flow path that allows the passage of a sphere with a diameter not smaller than the inner diameter of the end port of the valve body:

[Source: EN736-3]

3:2 flow coefficient flowcoefficient

KV The flow rate when water at a temperature of 5°C to 50°C passes through the valve and generates a static pressure (hydrostatic head) loss of 0:1MPa:

Note 1: Q=KV deltap where:

Q---flow, in cubic meters per hour (m3/h);

deltap---pressure drop, the unit is 0:1 MPa (0:1MPa):

Note 2: 1bar=0:1MPa=105Pa; 1MPa=1N/mm2:

[Source: EN736-3, with modifications]

3:3 full bore valve fulborevalve

The valve seat diameter is not less than 90% of the inner diameter of the end port of the valve body:

[Source: EN736-3] […]