Vibration Severity Checker - ISO 10816 / 20816 Zone Classification for Rotating Equipment
Classify machine vibration levels against ISO 10816 & ISO 20816 standards for pumps, motors, fans, compressors & turbines
Check vibration severity for rotating machinery against the widely used legacy ISO 10816-1 classification zones. Enter vibration velocity in mm/s or in/s (RMS, peak, or peak-to-peak with a disclosed sinusoidal conversion) and select the machine class (Class I-IV by power and foundation) to get a severity screen from Zone A (new machine condition) through Zone D (damage may be occurring). Includes the Class I-IV zone boundary reference table, a common fault-frequency diagnostic prompt, and measurement guidelines. ISO 10816-1 has been replaced by the ISO 20816 series; treat zone results as a screening guideline, not an acceptance limit, alarm/trip setpoint, reliability verdict, or operating decision.
Check coupling alignment as a vibration root cause
Coupling Alignment Calculator →Review bearing relubrication intervals
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Bearing Life Calculator →Read the vibration analysis basics guide
Vibration Analysis Basics →How It Works
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Select Machine Class
Choose the legacy ISO 10816-1 machine classification: Class I (small machines up to 15 kW), Class II (medium machines 15-75 kW), Class III (large machines over 75 kW on rigid foundations), or Class IV (large machines on flexible foundations). Different classes have different severity thresholds.
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Enter Vibration Reading
Input the overall vibration velocity value from your analyzer or portable meter in mm/s or in/s, and tell the tool whether the reading is RMS, peak, or peak-to-peak. Peak readings are converted to RMS using a disclosed sinusoidal assumption; direct RMS measurement is recommended.
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Review Severity Calculator
See the legacy zone classification: Zone A (new/reconditioned baseline), Zone B (legacy long-term-operation screen), Zone C (investigation prompt), or Zone D (urgent review prompt). Each zone shows the velocity ranges for your machine class.
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Reconcile Before Setpoint Decisions
Zone boundaries are general screening guidelines, not alarm/trip setpoints. Reconcile the result with the applicable current ISO 20816 machine-specific part, manufacturer acceptance limits, and your facility monitoring program before programming setpoints or making operating decisions.
Built For
- Vibration analysts performing route-based data collection on plant rotating equipment
- Maintenance planners using severity trends as review prompts before scheduling maintenance work
- Millwrights screening vibration after motor, pump, or fan installations before OEM or contract acceptance checks
- Reliability engineers using the zone table as a starting reference before qualified program-specific limit review
- Plant operators performing daily walk-around vibration checks with handheld meters
- Commissioning technicians screening readings before formal acceptance against contractual vibration limits
Features & Capabilities
Legacy ISO 10816-1 Zone Calculator
Classifies vibration into Zones A through D using the widely circulated legacy ISO 10816-1 Class I-IV guideline table, covering rigid and flexible foundation classes by power range. The tool discloses that ISO 10816-1 has been withdrawn and replaced by the ISO 20816 series.
Multi-Unit, Multi-Measurement Input
Accepts vibration velocity in mm/s or in/s, entered as RMS, peak, or peak-to-peak. Peak values are converted to RMS via the sinusoidal assumption (peak / sqrt(2)) with an explicit warning that the conversion is unreliable for real broadband machinery vibration.
Source Boundary Disclosure
Every result carries the source boundary: zone values are screening guidelines, not manufacturer acceptance limits, commissioning limits, or alarm/trip setpoints, and the applicable current standard may use a different scheme with different boundaries.
Zone Boundary Reference Table
Shows the full legacy Class I-IV boundary table (mm/s RMS) on screen and in the PDF report so the reading can be compared across classes and re-checked by a reviewer.
Diagnostic Frequency Reference
Quick-reference table of common vibration fault frequencies: 1× RPM (imbalance), 2× RPM (misalignment), bearing defect frequencies (BPFO, BPFI, BSF, FTF), gear mesh, and vane/blade pass frequencies to guide follow-up analysis.
Comparison
| ISO Zone | Class I (mm/s) | Class II (mm/s) | Class III (mm/s) | Class IV (mm/s) | Condition |
|---|---|---|---|---|---|
| Zone A | 0 - 0.71 | 0 - 1.12 | 0 - 1.8 | 0 - 2.8 | New machine baseline |
| Zone B | 0.71 - 1.8 | 1.12 - 2.8 | 1.8 - 4.5 | 2.8 - 7.1 | Acceptable long-term |
| Zone C | 1.8 - 4.5 | 2.8 - 7.1 | 4.5 - 11.2 | 7.1 - 18 | Investigate / short-term |
| Zone D | > 4.5 | > 7.1 | > 11.2 | > 18 | Damage occurring |
Assumptions
- Vibration measurements are taken at the bearing housing in the direction of highest amplitude.
- Machine is operating at steady-state conditions (not during startup, shutdown, or transients).
- Measurement instrument is calibrated and has adequate frequency range for the machine speed.
- Legacy ISO 10816-1 machine class is correctly selected for the equipment type and mounting.
- Velocity readings are broadband RMS values measured in the 10-1000 Hz frequency range.
Limitations
- Does not perform spectral analysis or identify specific fault frequencies (bearing, gear mesh, imbalance).
- Zone thresholds are general guidelines and may not apply to all machine configurations.
- Low-speed machines (below 120 RPM) may require displacement-based criteria instead of velocity.
- Does not account for structural resonance, foundation flexibility, or piping strain effects.
- Cannot replace trained vibration analyst interpretation for root cause diagnosis.
References
- ISO 10816-1:1995 (withdrawn) - Mechanical Vibration, Evaluation of Machine Vibration by Measurements on Non-Rotating Parts, Part 1 General Guidelines (basis of the legacy Class I-IV zone table).
- ISO 10816-3 - Mechanical Vibration, Evaluation of Machine Vibration by Measurements on Non-Rotating Parts.
- ISO 20816-1 - Mechanical Vibration, Measurement and Evaluation of Machine Vibration (general guidelines).
- ISO 2954 - Mechanical Vibration of Rotating and Reciprocating Machinery, Requirements for Instruments.
- Vibration Institute Category I-IV analyst training body of knowledge.