Overview
ISO 21014:2019 - "Cryogenic vessels - Cryogenic insulation performance" defines practical, standardized methods to determine the heat‑leak performance of cryogenic vessels. The standard covers measurement techniques for both open systems (where evaporated gas is vented) and closed systems (where mass is retained and pressure rises). It specifies test setup, stabilization, measurement duration and data correction procedures, but does not set pass/fail insulation performance limits or mandate when tests must be performed.
Key Topics
- Terms & definitions: clear definitions for open/closed systems, heat‑leak rate, holding time, static experimental holding time and maximum allowable filling mass.
- General test conditions: required stabilization, agreed test fluid (liquid nitrogen commonly used), instrumentation calibration, and reference conditions (ambient temperature and reference pressure specified in the standard).
- Heat‑leak measurement methods:
- Loss of product (direct mass loss or indirect via gas volumetric/mass flow measurement).
- Conversion of measured flow to mass flow (Annex A) and correction to reference conditions (Annex B).
- Test procedure: pre‑cooling, stabilization periods, starting fill level (typically 50% unless otherwise stated), minimum measurement duration (24 h after stabilization), and precautions to avoid liquid agitation.
- Calculations:
- Convert mass‑loss rate to equivalent heat leak (W) and to percentage loss per 24 h.
- Determination of equilibrium, optimum and static experimental holding times for closed systems using heat‑leak data and thermodynamic properties (Annex C for product equivalence).
- Reporting: required test report content and specification of accessories or conditions that influence results.
Applications
ISO 21014:2019 is practical for:
- Manufacturers and designers of cryogenic storage tanks and transport vessels validating insulation performance.
- Independent test laboratories performing cryogenic insulation testing and issuing comparative data.
- Operators and fleet managers assessing vessel holding times for safety and operational planning.
- Regulatory bodies and procurement teams that require standardized measurement methods (note: ISO 21014 does not prescribe acceptance criteria).
Practical benefits include reproducible heat‑leak data, comparable holding‑time estimates, informed selection of cryogenic fluids, and improved lifecycle planning for cold‑chain and gas distribution systems.
Related Standards
- Prepared by ISO/TC 220 (Cryogenic vessels).
- The standard supersedes ISO 21014:2006 and includes normative annexes for flow conversion and product equivalence. For thermodynamic property sources and calculation details, consult the bibliography referenced within ISO 21014:2019.
Keywords: ISO 21014, cryogenic vessels, cryogenic insulation performance, heat leak measurement, holding time, loss of product method, cryogenic insulation testing.
