Calculation Parameters

ISO 20816 – Evaluation of machine vibration by acceleration measurements





RPM




Calculation Results

Equipment Type:
—
Recommended Frequency Range:
—
Zone A (New Equipment) – up to:
—
Zone B (Long-term Operation) – up to:
—
Zone C (Short-term Operation) – up to:
—
Zone D (Damage) – above:
—

Vibration Acceleration Zone Interpretation:

Zone A: Vibration acceleration of new machines or after major overhaul
Zone B: Machines can operate indefinitely without risk of damage
Zone C: Condition monitoring required and maintenance planning necessary
Zone D: High risk of damage. Immediate intervention required

How the Calculator Works

ISO 20816 Standard

ISO 20816 complements ISO 10816 and establishes criteria for evaluating vibration using acceleration measurements. This standard is particularly important for high-frequency vibration components that are not always adequately reflected in velocity measurements.

Advantages of Acceleration Measurements

  • Better sensitivity to high-frequency components
  • Early detection of rolling bearing defects
  • Effective gear diagnostics
  • Cavitation detection in pumps

Relationship Between Acceleration and Velocity

Vibration acceleration is related to vibration velocity through frequency:

a = 2πf × v

where:

  • a — vibration acceleration (m/s²)
  • f — frequency (Hz)
  • v — vibration velocity (m/s)

Typical Threshold Values

Vibration acceleration threshold values depend on equipment type, frequency range, and operating conditions. General recommendations:

  • < 0.5 g: Excellent condition
  • 0.5-1.0 g: Good condition
  • 1.0-2.5 g: Satisfactory condition
  • 2.5-5.0 g: Unsatisfactory condition
  • > 5.0 g: Unacceptable condition

Application Features

  • For rolling bearings, measurement in the 10-10000 Hz range is recommended
  • For gear drives, analysis at tooth mesh frequencies is important
  • High-frequency measurements are used for cavitation diagnostics
  • Structural resonance frequencies must be considered

Measurement Recommendations

  • Use accelerometers with sufficient frequency range
  • Ensure reliable sensor mounting
  • Measure in three mutually perpendicular directions
  • Consider temperature effects on sensor sensitivity

Usage Examples & Value Selection Guide

Example 1: Centrifugal Pump with Rolling Bearings

Scenario: Monitoring a 30 kW centrifugal pump

  • Equipment Type: Centrifugal pump
  • Speed: 2950 RPM
  • Frequency Range: 10-1000 Hz (standard)
  • Bearing Type: Rolling bearings
  • Mounting: Rigid
  • Result: Zone A: 0-1.0 g, Zone B: 1.0-2.5 g
  • Note: For bearing defects, also check 10-10000 Hz
Example 2: Gas Turbine Generator

Scenario: 25 MW gas turbine with sleeve bearings

  • Equipment Type: Gas turbine (3-40 MW)
  • Speed: 5400 RPM
  • Frequency Range: 10-2000 Hz
  • Bearing Type: Sleeve bearings
  • Mounting: Flexible
  • Result: Zone A: 0-0.5 g, Zone B: 0.5-1.2 g
  • Critical: Monitor blade passing frequencies
Example 3: Reciprocating Compressor

Scenario: 4-cylinder reciprocating compressor

  • Equipment Type: Reciprocating compressor
  • Speed: 750 RPM
  • Frequency Range: 2-1000 Hz (low frequency)
  • Bearing Type: Sleeve bearings
  • Mounting: Vibration isolated
  • Result: Zone A: 0-2.0 g, Zone B: 2.0-5.0 g
  • Note: Higher limits due to inherent pulsations

How to Choose Values

Equipment Type Selection Guide
  • Gas Turbines:
    • < 3 MW: Small industrial turbines
    • 3-40 MW: Medium power generation
    • > 40 MW: Large utility turbines
  • Compressors:
    • Centrifugal: Smooth operation, lower limits
    • Reciprocating: Pulsating forces, higher limits
    • Screw: Medium limits, check harmonics
  • Electric Motors:
    • < 15 kW: Small auxiliary motors
    • 15-300 kW: Process motors
    • > 300 kW: Large drives
Frequency Range Selection
  • 10-1000 Hz: Standard for most rotating equipment
  • 10-2000 Hz: High-speed machines, gear boxes
  • 10-10000 Hz: Rolling bearing diagnostics, cavitation
  • 2-1000 Hz: Low-speed machines, reciprocating equipment
Bearing Type Considerations
  • Rolling Bearings:
    • More sensitive to high frequencies
    • Lower acceleration limits
    • Check bearing defect frequencies
  • Sleeve Bearings:
    • Better damping characteristics
    • Focus on low frequencies
    • Oil whirl/whip concerns
  • Magnetic Bearings:
    • Very low mechanical vibration
    • Check control system frequencies
    • Special evaluation criteria
Acceleration vs Velocity Measurements
  • Use Acceleration when:
    • High frequencies > 1000 Hz important
    • Rolling bearing monitoring
    • Gear mesh frequencies
    • Cavitation detection
  • Use Velocity when:
    • General machine condition
    • Low-medium frequencies (10-1000 Hz)
    • Unbalance, misalignment
    • Structural vibration