ISO 4266-1:2023

Overview

ISO 4266-1:2023 - "Petroleum and liquid petroleum products - Measurement of level and temperature in storage tanks by automatic methods - Part 1: Measurement of level in atmospheric tanks" provides requirements and guidance for the accuracy, installation, commissioning, calibration and verification of automatic level gauges (ALGs). It applies to both intrusive and non‑intrusive ALGs used in fiscal/custody transfer of petroleum and petroleum products with a Reid vapour pressure below 100 kPa stored in atmospheric tanks. This edition updates technical requirements (for example, still‑well perforation spacing) and clarifies measurement and recording practices.

Key topics and requirements

• Scope & applicability: ALGs for atmospheric storage tanks; not applicable to refrigerated storage tanks with ALG equipment.
• Types of ALGs: Covers intrusive (e.g., float, servo) and non‑intrusive (e.g., radar, microwave) instruments.
• Accuracy: Defines intrinsic instrument error, calibration before installation, installation/operation error sources, and overall accuracy expectations-especially for fiscal/custody transfer.
• Installation & mounting: Guidance on mounting location, manufacturer’s requirements, still‑well design (including updated perforation distances), and electrical/hazard safety.
• Commissioning & initial verification: Procedures for initial setting, manual reference measurements (ullage/dip), environmental considerations, and record keeping.
• Subsequent verification & calibration: Recommended frequency, verification tolerances and field procedures to maintain traceable measurement integrity.
• Precautions & safety: Instrument compatibility with product and environment, hazardous‑area certification, tamper protection and sealing for custody transfer use.
• Data communication: Requirements for reliable data transmission and receiving for monitoring and custody records.

Practical applications and users

ISO 4266-1:2023 is essential for:

• Tank operators and terminal managers implementing custody transfer measurement systems.
• Hydrocarbon custody transfer auditors, surveyors and metrologists ensuring legal and commercial accuracy.
• Instrument manufacturers and integrators designing and certifying ALGs for storage tanks.
• Regulatory bodies and national measurement organizations setting approval and type‑approval processes.
• Maintenance and calibration service providers applying prescribed verification and record‑keeping procedures.

Benefits include improved measurement reliability for inventory control, reduced transfer disputes, and compliance with international custody‑transfer measurement practice.

Related standards

• ISO 4266 series (other parts cover temperature and complementary topics)
• ISO 4266-4 (temperature measurement in tanks)
• ISO 1998 (petroleum industry terminology)

Keywords: ISO 4266-1:2023, automatic level gauge, ALG, custody transfer, storage tank measurement, ullage, dip, still‑well, calibration, verification.