CM Techniques Compared
Vibration, thermography, ultrasound, oil analysis — which technique detects what.
Read guide →Products
PdM Instruments & Condition Monitoring Equipment
Vibration data collectors, infrared cameras, ultrasound detectors, laser shaft alignment tools, and oil analysis kits — what each instrument detects, key specifications, and how to choose.
Building a PdM instrument kit — where to start
For a plant starting a PdM programme: (1) Start with an ultrasound detector — lowest cost (<£2,000), easiest to use, detects early bearing defects and air leaks immediately; (2) Add a vibration data collector/analyser — the core tool for rotating machinery condition monitoring; (3) Add an IR camera for annual electrical thermography surveys; (4) Add laser shaft alignment for mechanical work quality. Oil analysis is outsourced to labs — you only need sample bottles and a procedure. Priority for a small team: ultrasound → vibration → IR → alignment.
Vibration Analysers & Data Collectors
The core instrument for rotating machinery PdM. Ranges from simple single-channel route data collectors to sophisticated multi-channel analysers with onboard diagnostic software.
| Product tier | Key features | Typical cost (GBP) | Best for |
|---|---|---|---|
| Entry-level (route data collector) | Single-channel; overall vibration + FFT spectrum; route-based data collection; PC software for trending; accelerometer input | £1,500–4,000 | Small plant with <100 measurement points; technician-level analysis |
| Mid-range (data collector/analyser) | 1–2 channels; FFT spectra; envelope analysis; time waveform; bearing defect frequency calculation; balancing capability; route management software | £4,000–12,000 | Most industrial PdM programmes; balance of capability and cost |
| Advanced (full analyser) | Multi-channel simultaneous; high-resolution FFT; ODS (operating deflection shapes); modal analysis; advanced diagnostics; online system integration | £12,000–30,000+ | Specialist vibration analysts; complex machinery; research |
| Online continuous monitoring | Permanently installed sensors; 24/7 data; alerts; IIoT connectivity; edge computing | £500–2,000 per measurement point + system cost | Critical assets where manual rounds are insufficient; remote sites |
Key specification to check: frequency range (must cover 1 Hz to at least 10 kHz for bearing envelope analysis; 20 kHz ideal); dynamic range (dB — determines ability to detect small peaks in noise floor); FFT resolution (lines of resolution — 3,200 lines minimum; 6,400 for gear analysis).
Infrared Thermal Cameras
| Specification | Entry (£1,500–4,000) | Mid (£4,000–10,000) | Professional (£10,000–25,000+) |
|---|---|---|---|
| Detector resolution | 160×120 pixels | 320×240 pixels | 640×480 pixels or higher |
| Temperature range | −20°C to +350°C | −20°C to +650°C | −40°C to +2,000°C with ranges |
| Thermal sensitivity (NETD) | ≤100 mK | ≤50 mK | ≤20–30 mK |
| Measurement accuracy | ±2°C or ±2% | ±2°C or ±2% | ±1°C or ±1% |
| Recommended for | Annual LV electrical surveys; basic mechanical checks | Regular electrical and mechanical programmes; detailed reporting | HV surveys; precision industrial inspections; R&D |
Important: for electrical thermography surveys, ensure the camera has sufficient resolution to detect small hot spots in switchgear at a safe working distance. A 320×240 or 640×480 detector is strongly recommended for professional electrical surveys. Leading suppliers: FLIR, Hikmicro, Fluke, Testo.
Ultrasound Detectors
Airborne and structure-borne ultrasound instruments operating at 38–40 kHz. Detects: bearing defects (earliest possible detection — before vibration), compressed air and gas leaks, steam trap condition, electrical discharge (partial discharge, arcing, corona).
| Instrument type | Capability | Typical cost |
|---|---|---|
| Basic contact/airborne scanner | dBµV measurement; headphone listening; basic bearing and leak detection | £500–1,500 |
| Advanced (with data logging) | Route-based data collection; spectrum analysis; trending; ultrasound waveform; bearing alarm thresholds | £2,000–6,000 |
| Full suite (with spectral analysis) | Time waveform; FFT of ultrasound signal; bearing defect frequency detection in ultrasound domain; partial discharge detection | £4,000–12,000 |
Laser Shaft Alignment Tools
Laser alignment systems replace dial gauge methods — faster, more accurate, automatic tolerance guidance. Key selection criteria: number of measurement planes (1-plane for simple coupling alignment; 2-plane for soft-foot and simultaneous horizontal/vertical); live move display; tolerance tables for speed; wireless data transfer. Cost: £1,500 (basic) to £8,000+ (advanced with thermal growth compensation). Leading suppliers: SKF (Tksa series), Pruftechnik (Rotalign), FIXTURLASER.