ISO 9635-3:2014

Overview

ISO 9635-3:2014 - Agricultural irrigation equipment - Irrigation valves - Part 3: Check valves - specifies construction, performance requirements and test methods for hydraulically operated check valves used in agricultural irrigation systems. The standard applies to valves of DN 15 and larger, designed to operate fully open and fully closed (and capable of remaining in intermediate positions), with water temperatures up to 60 °C and exposure to fertilizers and agricultural chemicals.

Key topics and technical requirements

• Scope and definitions: clear definitions for check valves and flow-coefficient (Kv) used for performance claims.
• Design requirements: compliance with ISO 9635-1 general requirements (orientation, maintainability, marking of flow direction).
• Mechanical strength: tests for shell and pressure-containing parts and for obturator resistance to differential pressure; post-test function must not degrade by more than 10% versus manufacturer-declared values.
• Resistance to bending: bending moment tests defined as a function of DN to simulate in-line loads.
• Watertightness and seat tightness: internal and external pressure leak tests and seat tightness tests at high and low differential pressures.
• Hydraulic characteristics: head-loss or Kv must match manufacturer data; when measured per ISO 9644:2008, head loss shall not exceed 1.1× the declared value.
• Chemical resistance: materials and lubricants in contact with water must resist fertilizers/chemicals used in agriculture.
• Endurance: valves must withstand 2 500 opening/closing cycles (Annex A procedure) at approximately 1 m/s flow velocity and still pass leak tests; endurance testing not required for DN > 300.
• Conformity assessment: type tests, production control and quality-system requirements referenced to ISO 9635-1.

Practical applications

• Use ISO 9635-3:2014 to develop technical specifications for manufacturing, type-testing, and quality control of irrigation check valves.
• Aid procurement teams and irrigation system designers to select valves verified for chemical resistance, hydraulic performance and durability.
• Provide acceptance criteria for independent test laboratories and certification bodies performing leak, strength and endurance tests.
• Support maintenance teams by clarifying expected performance limits and required markings (e.g., flow direction) and recommending valve designs that permit in-line repair.

Who should use this standard

• Valve manufacturers and product engineers
• Irrigation system designers and agricultural engineers
• Test laboratories and conformity assessment bodies
• Procurement/specification writers for agricultural and landscape irrigation projects
• Maintenance and asset managers of irrigation networks

Related standards

• ISO 9635-1:2014 (General requirements for irrigation valves)
• ISO 9635 (Parts 1–5 covers isolating, check, air and control valves)
• ISO 9644:2008 (Pressure losses in irrigation valves - test method)

Keywords: ISO 9635-3:2014, check valves, irrigation valves, agricultural irrigation equipment, DN 15, endurance test, Kv, seat tightness, chemical resistance.