ISO 4266-3:2024

Overview

ISO 4266-3:2024 - Petroleum and liquid petroleum products: Measurement of level and temperature in storage tanks by automatic methods - Part 3 covers requirements and guidance for measuring liquid level in pressurized (non-refrigerated) storage tanks using automatic level gauges (ALGs). It applies to both intrusive and non‑intrusive ALGs used with petroleum and liquid petroleum products having a vapour pressure less than 4 MPa. The standard addresses accuracy, installation, commissioning, calibration and verification and gives specific guidance for custody/fiscal transfer applications. It does not apply to caverns or refrigerated storage tanks.

Key topics and technical requirements

• Types of ALGs covered: intrusive (e.g., float/servo) and non‑intrusive (e.g., microwave or radar) devices; innage vs ullage measurement concepts are defined.
• Accuracy and calibration: requirements on intrinsic ALG error, calibration prior to installation, errors introduced by installation/operating conditions, and rules for overall accuracy - with specific attention to custody transfer tolerances.
• Installation guidance: mounting location, manufacturer instructions, still‑well design and placement, guide wires, and requirements for non‑intrusive units (including radar/microwave on still‑wells).
• Commissioning and verification: procedures for initial setting and field verification (checking critical distances, free movement of sensing elements, effects of vapour/liquid properties), record keeping, and frequency/procedure for subsequent verifications and adjustments.
• Precautions and safety: hazardous‑area certification, material and electrical potential precautions, equipment suitability for design pressure/temperature, and manufacturer maintenance recommendations.
• Data communication: guidance on data transfer and receiving from ALGs to downstream systems.
• Terminology: clear definitions for datum plate, gauging reference point, ullage, still‑well, etc., aligned with ISO 1998 terminology.

Practical applications - who uses this standard

• Tank terminal operators and refinery storage managers implementing automated level monitoring.
• Custody transfer parties and commercial traders requiring verifiable, auditable level measurements.
• Metrology labs, calibration service providers and inspection bodies performing ALG type approval, installation verification and ongoing testing.
• Instrument manufacturers and system integrators designing, installing and certifying ALGs for pressurized tanks.
• Regulatory and national measurement organizations responsible for legal-for-trade approvals.

Related standards and references

• ISO 4266 series (other parts) for broader tank measurement topics.
• ISO 1998 (Petroleum industry - Terminology) for consistent definitions.

Keywords: ISO 4266-3:2024, automatic level gauge, ALG, measurement of level, pressurized storage tanks, petroleum products, custody transfer, installation, calibration, verification, still‑well, intrusive, non‑intrusive, radar, microwave.