Understanding Machine Vibration Evaluation Standards
This page provides educational guidance on the ISO 10816 vibration evaluation methodology. For the official numerical zone boundary values, please purchase the current ISO 10816 standard from iso.org or your national standards body. The specific limit values are copyrighted by ISO and are not reproduced here.
ISO 10816 is the international standard for evaluating machine vibration by measurements on non-rotating parts (bearing housings, pedestals, machine casings). It provides criteria for assessing vibration severity and establishing operational limits for industrial machinery.
| Part | Coverage |
|---|---|
| Part 1 | General guidelines |
| Part 2 | Large steam turbines & generators (>50 MW) |
| Part 3 | Industrial machines (>15 kW, 120-15,000 RPM) |
| Part 4 | Gas turbines with fluid-film bearings |
| Part 5 | Hydraulic power generating plants |
| Part 6 | Reciprocating machines (>100 kW) |
| Part 7 | Rotodynamic pumps |
ISO 10816-3 is the most widely used part, covering general industrial machines like motors, fans, compressors, and blowers in the 15 kW to 50 MW range.
ISO 10816 serves multiple purposes in industrial maintenance:
ISO 10816 evaluates overall vibration severity only. It does not diagnose specific faults. Use spectrum analysis and other diagnostic techniques to identify root causes.
Evaluates the absolute level of vibration against established zone boundaries. The measured broad-band RMS value is compared to limits based on machine type and support class.
Evaluates changes from baseline regardless of absolute level. A significant change may indicate developing problems even if Zone C hasn't been reached.
ISO 10816 defines four evaluation zones (A, B, C, D) to provide a qualitative assessment of machine vibration severity. Each zone indicates the general condition and suggests appropriate actions.
Vibration of newly commissioned machines would normally fall within this zone. This represents the best achievable condition for a properly installed and balanced machine. Not all machines will achieve Zone A, but it's the target for new installations.
Machines with vibration within Zone B are normally considered acceptable for unrestricted long-term continuous operation. This is the normal operating zone for most well-maintained industrial machinery. No immediate action required.
Establish your baseline vibration levels when the machine is in Zone A or B. This reference point is essential for Criterion II evaluation and trend analysis.
Machines with vibration in Zone C are normally considered unsatisfactory for long-term continuous operation. The machine may be operated for a limited period until a suitable opportunity arises for remedial action. Plan maintenance and investigate the cause.
Vibration values within Zone D are normally considered severe enough to cause damage to the machine. Continued operation at these levels risks catastrophic failure, secondary damage, and safety hazards. Immediate action is required.
Zone D vibration levels can cause rapid bearing degradation, seal failures, coupling damage, foundation cracking, and catastrophic machine failure. Do not ignore!
Provides warning that a defined vibration level has been reached or a significant change has occurred. Investigation is warranted but continued operation is typically acceptable during investigation.
Recommended: Set ALARM relative to baseline, typically not exceeding 1.25Γ the upper limit of Zone B
Specifies the magnitude beyond which further operation may cause damage. If TRIP is exceeded, take immediate action to reduce vibration or shut down the machine.
Recommended: TRIP within Zone C or D, typically not exceeding 1.25Γ the upper limit of Zone C
Alarm and trip settings should be machine-specific based on baseline measurements, criticality, and operating experience. The ISO recommendations are starting points - adjust based on your specific situation and historical data.
ISO 10816-3 classifies machines based on power rating or shaft height and support flexibility. Different zone boundaries apply to each classification because larger machines and flexible supports naturally have different vibration characteristics.
The support system is considered rigid if the lowest natural frequency of the combined machine-support system is at least 25% higher than the main excitation frequency (usually running speed).
Typical Examples:
All support systems that do not meet the rigid criteria are considered flexible. This includes systems where the natural frequency is close to or below the running speed.
Typical Examples:
A support may be rigid in one direction and flexible in another (e.g., stiff vertically but flexible horizontally). In such cases, evaluate each measurement direction according to its corresponding support classification.
Measurements should be taken on exposed parts of the machine that are normally accessible, typically at or near bearing housings or pedestals.
Broad-band RMS Velocity (mm/s or in/s)
Primary evaluation parameter for most machines
10 Hz to 1,000 Hz
For machines below 600 RPM: extend lower limit to 2 Hz
Displacement (Β΅m or mils)
Required for low-speed machines with significant low-frequency content
Measurement equipment must be capable of measuring broad-band RMS vibration with flat frequency response over the specified range.
Determine if your machine falls under ISO 10816-3 (or another part). Identify the Group (1 or 2) based on power rating or shaft height. Determine support flexibility (rigid or flexible).
Install sensors at appropriate locations (bearing housings). Configure for broad-band RMS velocity measurement (10-1000 Hz). Ensure proper sensor mounting to avoid resonance effects.
Ensure machine is at normal operating temperature and steady-state conditions. Record speed, load, voltage, and other relevant parameters. Check for excessive background vibration.
Measure broad-band RMS velocity at each point. For low-speed machines, also measure displacement. Record the higher value from orthogonal measurements at each plane.
Compare measured values to zone boundaries for your machine classification (refer to ISO 10816 standard for specific values). The most restrictive zone applies when comparing velocity and displacement.
Compare to established baseline. Investigate significant changes (typically >25% of Zone B upper limit) even if still in acceptable zone. Applies to both increases AND decreases.
Zone A/B: Continue operation, establish baseline. Zone C: Plan remedial action, investigate cause, limit operation time. Zone D: Immediate action required, risk of damage.
Recommended for large or critical machinery. Permanently installed sensors with online monitoring systems. Enables real-time alarming and automated trending.
Common for smaller or non-critical machines. Portable instruments or route-based data collection. Frequency depends on criticality and failure history.
Both approaches benefit from computerized trending and historical comparison. The choice depends on machine criticality, failure consequences, and cost-benefit analysis.
ISO 10816 tells you how severe the vibration is, but not why it's occurring. For root cause identification, you need diagnostic techniques:
Identify frequency components and their sources
Detect impacts, looseness, and rubs
Distinguish unbalance from misalignment
Early bearing fault detection
Shaft motion in fluid-film bearings
Track degradation over time
General guidelines for evaluating machine vibration by measurements on non-rotating parts. The foundation document for the entire series.
iso.org - ISO 10816-1 βIndustrial machines with power above 15 kW and speeds 120-15,000 RPM. The most commonly used part for general industrial machinery.
iso.org - ISO 10816-3 βEvaluation of machine vibration by measurements on rotating shafts. Complementary to ISO 10816 for machines with proximity probes.
iso.org - ISO 7919-1 βRequirements for instruments for measuring vibration severity. Defines the measurement equipment specifications referenced in ISO 10816.
iso.org - ISO 2954 βThe newer series that is gradually replacing ISO 10816. Check for updates specific to your machine type.
iso.org - ISO 20816 βAmerican National Standards Institute - US source for ISO standards adoption and related American standards.
webstore.ansi.org β| Standard | Application |
|---|---|
| ISO 1940 | Balance quality requirements for rotors |
| ISO 14694 | Industrial fans - balance quality and vibration |
| ISO 8579-2 | Gear unit vibration acceptance |
| IEC 60034-14 | Rotating electrical machines vibration |
| API 610 | Centrifugal pumps for petroleum industry |
| API 617 | Axial and centrifugal compressors |
ISO 18436-2 compliant vibration analyst certification (Category I-IV). Training courses and educational resources.
vi-institute.org βISO 18436-2 compliant certification and training. Board of certification for vibration analysts.
mobiusinstitute.com βVibration analysis training and consulting services. Diagnostic resources and case studies.
technicalassociates.net βTake baseline readings on new or recently repaired machines under consistent operating conditions. This reference is essential for Criterion II and trending. Document all conditions.
Use the same sensor locations, orientations, and operating conditions for trend comparisons. Mark measurement points permanently. Use consistent data collection procedures.
ISO 10816 overall values are a screening tool. Always collect spectrum data for diagnostic capability. A machine can have acceptable overall levels but developing component problems.
Some machines never achieve Zone A even when new. Others may have historically run in Zone A. Use machine-specific experience alongside standards. Document "normal for this machine" values.
A sudden change in vibrationβeven within acceptable zonesβoften indicates a developing problem. Investigate changes of 25% or more from baseline regardless of absolute level.
Equipment manufacturers may specify tighter limits than ISO 10816 general values. Always check OEM documentation. Use the more conservative limit when in doubt.
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