ISO 9635-2:2014

Overview

ISO 9635-2:2014, "Agricultural irrigation equipment - Irrigation valves - Part 2: Isolating valves", defines construction, performance requirements and test methods for isolating irrigation valves. It applies to valves of DN 8 and larger, for use in irrigation water (≤ 60 °C) that may contain fertilizers and typical agricultural chemicals. The standard covers valves designed to operate in fully open and fully closed positions but which may remain for extended periods in intermediate positions.

Key topics and technical requirements

• Scope and applicability: Valves for agricultural irrigation systems (DN ≥ 8), water temperature limit 60 °C, compatible with fertilizers and agricultural chemicals.
• Design requirements: Conformance with general requirements in ISO 9635-1:2014 (materials, dimensions, end types, marking).
• Mechanical strength: Pressure shell strength, obturator resistance to differential pressure, and bending-resistance tests with specified bending moments by DN.
• Watertightness / airtightness: Shell and pressure-component tests, plus seat tightness at high and low differential pressures with leakage-rate limits (different for resilient and metallic seats).
• Operating torque: Definition of Maximum Operating Torque (MOT) and Minimum Strength Torque (mST). MOT formulas are provided for handwheels (MOT = 0.5 × F × D) and levers (MOT = F × L), with specific rules for T-keys, butterfly, gate and actuated valves. mST is typically 2 × MOT (gate valves 5 × MOT for certain tests).
• Hydraulic characteristics: Flow coefficient Kv (K_V) requirements and head-loss reporting; measured Kv must be within ±5% of declared value when tested per ISO 9644.
• Resistance to chemicals: Requirements for materials and lubricants in contact with treated irrigation water.
• Endurance testing: Cyclic operation tests (250 cycles for manual valves; 2 500 for electrically/hydraulically/pneumatically operated valves) at allowable operating pressures with leakage acceptance criteria.
• Conformity assessment: Type testing, production control, marking and packaging requirements are aligned with ISO 9635‑1:2014.
• Normative annexes: Annexes A–E provide test methods for operating loads, torque for gate valves, operation and endurance tests, and sizing of the operating element.

Applications and users

Who uses ISO 9635-2:2014:

• Valve manufacturers for design verification, type testing and CE/market compliance.
• Irrigation system designers and specifiers when selecting isolating valves for agricultural networks.
• Test laboratories and certification bodies performing mechanical, hydraulic and chemical-resistance tests.
• Procurement and quality teams ensuring supplied valves meet required torque, leakage and endurance performance.
• Farm and irrigation managers / installers relying on certified valve performance for long-term system reliability.

Related standards

• ISO 9635-1:2014 - General requirements for irrigation valves
• ISO 9644 - Test method for pressure losses in irrigation valves
• Other parts of ISO 9635 series: Part 1 (general), Part 3 (check valves), Part 4 (air valves), Part 5 (control valves)

Keywords: ISO 9635-2:2014, isolating valves, irrigation valves, agricultural irrigation equipment, DN 8, valve endurance, watertightness, operating torque, flow coefficient.