Overview
ISO 12714:1999 - Non-destructive testing - Acoustic emission inspection - Secondary calibration of acoustic emission sensors - specifies a standardized method for secondary calibration of acoustic emission (AE) sensors as receivers of elastic surface waves (Rayleigh waves). The standard defines how to transfer a primary calibration through a reference sensor (RS) to a sensor under test (SUT), yielding the sensor frequency response and sensitivity in the range 100 kHz to 1 MHz. Calibration results are reported in volts per unit mechanical input (displacement, velocity or acceleration).
Key topics and requirements
- Calibration principle: Comparative measurement - RS and SUT mounted on the same test block surface and excited by a common source so the free-surface motion at both sensor locations is nominally identical.
- Frequency response: Sensitivity typically determined at intervals of about 10 kHz across 100 kHz–1 MHz; results can be expressed in frequency-domain magnitude/phase or time-domain transient response.
- Units: Volts per metre (displacement) or volt-seconds per metre (velocity), consistent with free-surface motion input.
- Test block: Material (acoustic impedance) strongly influences results. Prototype and primary calibrations use steel (A36) test blocks with strict dimensional, surface-roughness and ultrasonic-inspection criteria; other block materials require documented traceability to a primary calibration on the same material.
- Source options: Small-aperture transient or CW sources (e.g., glass-capillary break, spark, tone-burst or pulse transducer). Source repeatability must be established if channels are tested sequentially.
- Reference sensor: RS must have a known primary calibration and a relatively flat response over 100 kHz–1 MHz (prototype uses an NBS conical transducer).
- Data acquisition & processing: Synchronous waveform capture, adequate sampling/bit-depth (examples: 8-bit @ 20 MHz or 10-bit @ 10 MHz), FFT-based processing, and procedures to avoid reflections and windowing artifacts.
- Performance checks: Sections cover expected uncertainties, proof testing of the calibration system and typical calibration result reporting.
Applications and users
ISO 12714 is used by:
- NDT laboratories performing AE sensor calibration and traceability transfer
- Calibration and metrology labs establishing tertiary standards
- AE system manufacturers and sensor designers for performance verification
- Inspection engineers and quality assurance teams requiring quantitative AE measurements
- Research groups working on AE sensor characterization and method development
Practical uses include ensuring accurate sensor sensitivity for structural health monitoring, AE-based leak detection, fatigue/crack monitoring, and other AE inspection programs where quantitative amplitude and frequency response matter.
Related standards
- ISO 12713:1998 - Primary calibration of transducers
- ISO 12716 - AE vocabulary
- ASTM E1106 - Primary calibration of AE sensors
- ASTM E114 - Ultrasonic pulse-echo testing (test-block inspection)
- ASTM E1316 - Nondestructive examination terminology
Keywords: ISO 12714:1999, acoustic emission, secondary calibration, AE sensors, Rayleigh waves, test block, reference sensor, non-destructive testing, frequency response.