Overview
ISO 13758:1996/Amd 1:2020 is an international standard issued by ISO (International Organization for Standardization) that specifies the valve freeze method for assessing the dryness of propane in liquefied petroleum gases (LPG). This amendment updates the original 1996 edition, adding critical procedures to ensure the accuracy and reliability of propane dryness assessment, which is essential for safety and performance in LPG applications.
The standard focuses on verifying the correct flow rate through the test valve, which directly impacts the precision of the valve freeze method. It introduces a new clause on apparatus verification and provides a detailed normative annex outlining the procedure for flow rate verification using nitrogen gas.
Key Topics
- Assessment of dryness of propane: Ensures propane LPG is free from moisture, preventing equipment corrosion, valve freeze, and operational hazards.
- Valve freeze method: A diagnostic technique used to assess propane dryness by observing temperature changes and freezing behavior in the valve during testing.
- Apparatus verification: New clause added to ensure the flow rate through the propane test valve is correct, thereby guaranteeing test accuracy.
- Flow rate verification procedure:
- Use of a calibrated flow meter to measure flow rate from 500 ml/min to 900 ml/min.
- Requirement to verify flow using a reference valve with a calibration certificate.
- Nitrogen gas as verification medium at specified pressure and temperature (275 kPa ± 5 kPa at 21 °C).
- Acceptable test valve flow rate range is 600 ml/min to 800 ml/min.
- Valve adjustment and maintenance: If the test valve flow rate is out of range, it must be adjusted per manufacturer’s instructions or returned for reconditioning and recalibration.
- Normative references: Updated reference to ISO 4257, LPG sampling method, ensuring consistency in sample handling.
Applications
ISO 13758:1996/Amd 1:2020 serves as a critical guide for industries handling propane within LPG mixtures, including:
- Petroleum and LPG producers: To maintain product quality by ensuring propane dryness during production and storage.
- LPG distributors and wholesalers: For quality assessment during transport and before delivery to end-users.
- Equipment manufacturers: To develop valves and analytical tools complying with flow rate and dryness assessment requirements.
- Quality control laboratories: For routine testing of propane dryness using standardized, validated flow verification methods.
- Safety inspectors and regulators: To enforce compliance with international LPG safety standards, mitigating risks related to valve freeze and moisture-related failures.
Compliance with this standard ensures operational safety, efficient fuel combustion, longer equipment lifespan, and reduced maintenance costs related to moisture contamination.
Related Standards
-
ISO 4257: Liquefied petroleum gases - Method of sampling
This standard complements ISO 13758 by defining proper sampling techniques required for accurate dryness assessment testing.
-
ISO/TC 28 Standards
The technical committee responsible for petroleum and related products, including fuels and lubricants, ensures harmonization across LPG testing, sampling, and quality evaluation standards.
-
ISO/IEC Directives
Guidelines on the preparation and maintenance of ISO documents, underlying the editorial and procedural consistency reflected in this amendment.
By adhering to ISO 13758:1996/Amd 1:2020, industry stakeholders ensure the reliable and standardized assessment of propane dryness using the valve freeze method, enhancing product safety and regulatory compliance across global LPG markets.