Overview
ISO 18132-2:2008 defines general requirements for automatic level gauges (ALG) used to measure liquid level of refrigerated light hydrocarbon fluids (primarily LNG and LPG) stored in bulk, near-atmospheric refrigerated-type shore tanks. It covers specification, installation, and calibration/verification testing of ALGs on shore tanks and is explicitly not applicable to pressurized shore tanks. The part complements ISO 18132-1 (onboard ships) and references OIML R 85 for automatic level gauge conformity.
Key topics and technical requirements
- Scope & applicability: ALGs for cryogenic, near-atmospheric refrigerated tanks (LNG/LPG). Excludes pressurized tanks.
- Design and specification:
- Must withstand cryogenic conditions, corrosion, turbulence and vibration.
- Electromagnetic compatibility (EMC) and protection against electrostatic/lightning required (refer OIML D11).
- Self-diagnostics, tamper security (e.g., software passwords), and provisions for routine maintenance and field calibration.
- Recommended minimum resolution: 1 mm or better.
- Installation:
- Follow manufacturer instructions and regulatory requirements.
- Redundancy recommended: install two or more independent ALGs per tank; designate one as primary.
- Locate gauges to minimize boiling/turbulence effects and provide isolation for maintenance.
- Calibration & verification (accuracy tests):
- Two-step initial verification: 1) prior to shipment and 2) after installation. Reference standards must be traceable to national standards.
- Tolerances:
- Prior-to-installation comparison to reference: ±3 mm over operating range.
- After-installation (tank out of service): ±7.5 mm against tank reference points.
- In-service verification and subsequent periodic checks: ±10 mm tolerance (annual recommended).
- Subsequent verification frequency recommended at least annually, subject to national metrology rules.
- Measurement considerations: Defines terms (datum level, ullage/innage, reference points) and emphasizes compensation for thermal contraction, fluid physical property changes and minimal unmeasured zones.
Applications and users
ISO 18132-2:2008 is used by:
- Tank farm and terminal operators for inventory control, process control and custody transfer.
- ALG manufacturers and suppliers for product specification and certification.
- Installation contractors and instrumentation engineers for correct placement and commissioning.
- Calibration laboratories, metrology authorities and regulatory bodies for conformity testing and audits.
- Asset owners and trading parties requiring reliable level measurement for commercial transactions.
Related standards
- OIML R 85 - Automatic level gauges for fixed storage tanks (referenced normative standard)
- ISO 18132-1 - Gauges onboard ships carrying liquefied gases
- ISO 8310 - Temperature measurement (referenced in Annex A for temperature-related corrections)
Keywords: ISO 18132-2:2008, automatic level gauge, ALG, LNG, LPG, refrigerated shore tanks, calibration, verification, OIML R 85, tank level measurement.
Open preview (PDF)Refrigerated light hydrocarbon fluids — General requirements for automatic level gauges — Part 2: Gauges in refrigerated-type shore tanks
