ISO 19973-2:2015

Overview

ISO 19973-2:2015 - "Pneumatic fluid power - Assessment of component reliability by testing - Part 2: Directional control valves" specifies test procedures, equipment and reporting methods for assessing the reliability of pneumatic and electro-pneumatic directional control valves. It complements ISO 19973-1 (general procedures) and defines how lifetime is expressed (cycles), how the three-points moving average (3PMA) method is applied to determine first failure (without repairs, excluding outliers), and the threshold levels used to judge failures.

Key Topics and Requirements

• Scope and lifetime unit: Lifetime is expressed in cycles; whenever the standard uses “time” it means cycles.
• Test equipment: Basic circuits for testing two-position (bi-stable and mono‑stable) and three‑position valves, rules for silencers, pilot supply and safety considerations.
• Connecting piping and volumes: Guidance to avoid flow restrictions; keep tubing short so volumes charge/vent within control-signal timing.
• Test conditions: Initial functional checks; cycling requirements (outlet pressures must fall below 10% and rise above 90% of supply during a cycle); actuation on/off ratio 1:1.
• Control signals: Defined patterns for mono‑stable and bi‑stable/three‑position valves to ensure reproducible cycling.
• Checks and measurements:
  • Functional checks (acoustic, visual, tactile) to detect switching failures or incomplete charging.
  • Leakage measurements (functional leakage and specific internal/external pilot leak checks depending on valve type).
  • Measurement of shifting pressures (performance change over cycles).
• Failure criteria and thresholds: Criteria for functional failure, leakage failure and shifting-pressure failure; customizable agreements allowed between parties.
• Data analysis and reporting: Use methods from ISO 19973-1 for statistical analysis and prepare a standardized test report.

Applications and Users

ISO 19973-2:2015 is intended for:

• Valve manufacturers - for design validation, production testing and reliability claims.
• Test laboratories and OEMs (machine builders) - to evaluate component reliability, set maintenance intervals, and optimize spare-part inventories.
• Reliability and quality engineers - for reliability modelling, warranty analysis and continuous improvement. Practical uses include predicting valve lifetime in cycles, establishing service schedules, and informing FMEA, design changes and production acceptance tests.

Related Standards

• ISO 19973-1 (General procedures)
• ISO 1219-1 (Graphical symbols)
• ISO 5598 (Vocabulary)
• ISO 8778 (Standard reference atmosphere)
• ISO 80000-1 (Units)
• IEC 60050-191 (Dependability vocabulary)

Keywords: ISO 19973-2:2015, pneumatic directional control valves, reliability testing, 3PMA, leakage measurement, cycling frequencies, test procedures, threshold levels.