Condition Monitoring Technologies – Application Comparison
Modern reliability programs use multiple condition monitoring technologies, each designed to detect specific types of faults. No single method identifies all failure modes. Effective diagnostics rely on selecting the appropriate tool based on the physics of the problem.
Vibration Analysis
Vibration analysis measures the dynamic response of rotating equipment and structures.
Best suited for:
- Imbalance (1× running speed)
- Misalignment
- Mechanical looseness
- Bearing defects (with envelope detection)
- Structural resonance
Strengths:
- Quantitative and trendable
- Detects a wide range of mechanical faults
- Provides frequency-based diagnostics
Limitations:
- Less sensitive to very early-stage defects
- Requires proper sensor placement and interpretation
Ultrasonic / High-Frequency Detection
Ultrasonic methods detect high-frequency energy generated by friction, impacting, or turbulence.
Best suited for:
- Early-stage bearing defects
- Lubrication issues
- Compressed air and gas leaks
- Electrical discharge
Strengths:
- Highly sensitive to early faults
- Works in noisy environments
- Fast inspection method
Limitations:
- Limited diagnostic detail compared to vibration
- Requires experience to interpret signal characteristics
Acoustic Imaging (Sound Camera)
Acoustic imaging uses microphone arrays to locate sound sources and display them visually.
Best suited for:
- Compressed air and gas leaks
- Vacuum and steam leaks
- Electrical faults (arcing, corona, tracking)
- General noise source identification
Strengths:
- Rapid scanning of large areas
- Visual identification of fault location
- Non-contact measurement
Limitations:
- Limited for low-frequency mechanical issues
- Primarily a detection tool, not detailed diagnosis
Operating Deflection Shape (ODS)
ODS visualizes how equipment or structures move during operation.
Best suited for:
- Structural looseness
- Resonance conditions
- Base and foundation issues
- Relative motion between components
Strengths:
- Shows actual operating behavior
- Identifies structural problems not visible in spectra
- Supports root cause analysis
Limitations:
- Requires multiple measurements
- Interpretation depends on analyst experience
Video ODS
Video ODS uses camera-based motion amplification to visualize vibration.
Best suited for:
- Structural flexing and resonance
- Large or complex structures
- Rapid visual confirmation of movement
Strengths:
- Non-contact
- Quick setup
- Easy to communicate findings visually
Limitations:
- Less precise than sensor-based ODS
- Limited quantitative accuracy
Practical Application
In a typical troubleshooting scenario:
- Vibration analysis identifies elevated 1× running speed
- ODS or Video ODS reveals structural amplification at the base
- Ultrasound confirms no bearing distress
- Acoustic imaging rules out leaks or external noise sources
This combined approach isolates the issue to a structural resonance condition, allowing targeted corrective action.
Summary
Each technology provides a different perspective:
- Vibration → What is happening (frequency and severity)
- Ultrasound → Early-stage fault detection
- Acoustic Imaging → Where the issue is located
- ODS / Video ODS → How the structure is moving
Using these methods together provides a comprehensive understanding of machine condition and supports accurate, defensible maintenance decisions.