ISO 18132-2:2008

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.