Overview
ISO 21922:2021/Amd 1:2024 is the latest amendment to the international standard governing valves used in refrigerating systems and heat pumps. Published by the International Organization for Standardization (ISO), this amendment updates requirements for valve design, testing, and marking to enhance safety, reliability, and environmental performance. It focuses particularly on seat tightness-a critical factor in preventing refrigerant leakage-and provides new methodology for leak testing and classification of valves.
This amendment supports manufacturers, testing bodies, and equipment users in aligning with best practices for controlling leaks in refrigeration and heat pump systems, thereby improving efficiency and reducing environmental impact from refrigerant emissions.
Key Topics
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Seat Tightness Classification
The amendment introduces updated seat tightness classes (A through H), defining maximum permissible leakage percentages and testing requirements. Class A and B valves are designed with the highest leak-tightness levels, essential for valves venting to the atmosphere during service or permanently.
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Leakage Testing Methods
Detailed procedures for type testing valves using air or nitrogen specify how to measure leakage volume and mass flow rates. The amendment provides improved formulas to calculate leakage percentages based on upstream and downstream measurements, valve flow coefficients, pressure differentials, and gas densities.
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Production Test Requirements
Production-level tests ensure consistent seat sealing capacity, verifying valve leak rates at defined differential pressures. The amendment mandates zero bubbles or limits based on valve size and leakage class to guarantee manufacturing quality control.
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Back Seat Valve Testing
Requirements to verify the tightness of back seats to allow safe maintenance of valve packing while the system remains pressurized.
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Leakage Rate Estimation
Annex N introduces practical formulas to estimate refrigerant leakage mass flow from known leakage percentages, refrigerant densities, and operating pressure conditions, helping assess the environmental impact and performance loss due to leaks.
Applications
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Refrigeration Systems
Ensures valves in industrial and commercial refrigeration lines maintain tight seals to prevent refrigerant leaks that could impair cooling efficiency and cause environmental harm.
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Heat Pumps
Guarantees valves meet stringent leakage limits to optimize heat pump operation, preserving energy efficiency and minimizing refrigerant emissions.
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Safety-Critical Valves
Applies to safety and relief valves where zero leakage or minimal leakage is critical to system integrity and operator safety.
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Valve Manufacturing and Certification
Provides standardized requirements and testing processes manufacturers must comply with for valve certification and market acceptance.
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Maintenance and Quality Control
Assists service providers in performing leak-tightness assessments and identifying valves requiring repair or replacement.
Related Standards
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ISO/IEC Directives, Part 1 and Part 2
Guidelines referenced for the preparation and maintenance of ISO documents, including ISO 21922 amendments.
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IEC 60534-2-1
Provides more comprehensive formulas and factors for flow measurement and valve leakage calculations, complementary to the leakage estimation methods in ISO 21922.
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CEN/TC 182 Standards
European standards on refrigerating systems safety and environmental requirements, developed jointly with ISO/TC 86 under the Vienna Agreement.
Practical Value
Implementing ISO 21922:2021/Amd 1:2024 enables refrigeration and heat pump industry stakeholders to:
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Minimize refrigerant emissions through rigorous seat tightness standards, reducing environmental impact and improving compliance with global climate protocols.
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Ensure valve reliability and safety by defining uniform testing procedures and leakage thresholds.
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Facilitate product certification and market acceptance via harmonized international valve standards.
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Optimize system performance by maintaining valve integrity, essential for energy-efficient operation of refrigeration and heat pump equipment.
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Support maintenance and lifecycle management with detailed guidance on detecting and measuring valve leakage.
By adhering to this amendment, manufacturers and operators promote sustainable, safe, and efficient refrigeration and heat pump installations across diverse applications worldwide.