ISO 10816-1: Mechanical vibration – Evaluation of machine vibration by measurements on non-rotating parts – Part 1: General guidelines

Summary

ISO 10816-1 is a cornerstone standard for machinery condition monitoring. It provides the general principles for measuring and assessing vibration on the non-rotating or stationary parts of machines, such as bearing housings. This standard is the modern replacement for the historical ISO 2372 and serves as the parent document for a series of other standards (e.g., ISO 10816-3 for industrial machines) that provide specific vibration limits for different classes of machinery. Its primary goal is to provide a standardized, reliable basis for evaluating the operational health of machines and for setting acceptance criteria.

Note: This standard is gradually being superseded by the ISO 20816 series, which aims to combine the principles of casing measurements (ISO 10816) and shaft measurements (ISO 7919) into a single, comprehensive framework. However, the principles and zone definitions of ISO 10816-1 remain in widespread use.

Table of Contents (Conceptual Structure)

The standard is structured to provide a complete framework for setting up and running a machinery vibration assessment program:

1. 1. Scope and Measurement:

   This initial section defines the standard’s scope, making it clear that it applies to the measurement of structural vibration on the stationary, non-rotating parts of machinery, primarily bearing housings. It establishes that the preferred measurement parameter for condition monitoring purposes is broadband root-mean-square (RMS) velocity, as it provides a stable and representative measure of the vibration’s destructive energy over a wide range of machine speeds. The standard specifies a default frequency range for this measurement, typically 10 Hz to 1,000 Hz, which is effective for detecting the most common machine faults like unbalance and misalignment. It also provides foundational guidance on where to take measurements (on the bearings in horizontal, vertical, and axial directions) to ensure a complete picture of the machine’s dynamic state.

2. 2. Instrumentation:

   This chapter provides the performance requirements for the instruments used to make the measurements. It specifies that the entire measurement system, including the sensor, cabling, and meter, must be capable of accurately measuring RMS velocity within the specified frequency range. It mandates that the instrument must have a dynamic range sufficient to measure both very smooth-running and rough-running machines without distortion. The standard also places a strong emphasis on correct sensor mounting to ensure data accuracy and repeatability, and it directly references ISO 5348 as the governing standard for accelerometer mounting. Finally, it requires that the instrumentation be periodically calibrated to a traceable standard to ensure its ongoing accuracy.

3. 3. Evaluation Criteria:

   This core section establishes the two fundamental philosophies for assessing vibration severity. It explains that a comprehensive evaluation should not rely on a single method, but on a combination of both:

   • Criterion 1: Vibration Magnitude. This is an assessment of the absolute value of vibration measured at a specific point in time, compared against predefined limits (the “zones” described in the next section). This criterion is used to judge the machine’s condition in an absolute sense and is essential for acceptance testing and for setting upper limits to prevent damage.
   • Criterion 2: Change in Vibration Magnitude. This criterion focuses on the trend of vibration over time, comparing the current value to the machine’s established normal baseline. The standard emphasizes that a significant *change* in vibration, such as a doubling of the RMS velocity, can be a much more sensitive indicator of a developing fault than the absolute value alone. A machine’s vibration could double but still be in the “Good” or “Satisfactory” zone, yet this change would still be a clear warning sign that requires investigation.
4. 4. Evaluation Zones:

   To provide a simple, actionable framework for Criterion 1 (absolute magnitude), the standard introduces a system of four evaluation zones. These zones serve as universal “grades” for machine condition. It is important to note that this general part of the standard only defines the *concept* of the zones; the specific numerical values for the zone boundaries (in mm/s) are provided in the machine-specific parts of the standard (e.g., ISO 10816-3). The zones are defined as:

   • Zone A: The vibration of newly commissioned machinery would normally fall into this zone.
   • Zone B: Machines with vibration within this zone are normally considered acceptable for unrestricted long-term operation.
   • Zone C: Machines with vibration within this zone are normally considered unsatisfactory for long-term continuous operation. The machine may be operated for a limited period in this condition until an opportunity arises for remedial action.
   • Zone D: Vibration values within this zone are normally considered to be of sufficient severity to cause damage to the machine.
5. 5. Operational Limits (Alarms):

   This final section provides a practical methodology for implementing the evaluation criteria in a real-world monitoring program. It advises setting two distinct levels of operational alarms to manage machine risk effectively:

   • Alert: This is a warning level, set to indicate that the vibration has exceeded its normal, stable, baseline value. An Alert is not necessarily an indication of immediate danger, but it serves as a trigger for increased monitoring or for scheduling an investigation to determine the cause of the change. This limit is typically based on Criterion 2 (a significant change from the baseline).
   • Trip: This is a shutdown level, set at a higher, absolute value that represents the upper limit of acceptable operation. If this level is breached, it indicates that the machine is at risk of imminent and severe damage. The response should be immediate action, which may include shutting the machine down. This limit is typically based on Criterion 1 (an absolute magnitude, often the Zone C/D boundary).

Key Concepts

• RMS Velocity: The standard reaffirms RMS velocity as the best single metric for overall machinery health in the specified frequency range, as it is directly related to the destructive energy of the vibration.
• Broadband Measurement: The standard is based on a single “overall” vibration value, not a detailed spectrum. It is a screening tool, not a diagnostic one. A high value tells you *that* there is a problem, but not *what* the problem is.
• General vs. Specific: Part 1 is the general framework. For specific, actionable vibration limits for a particular machine, you must refer to the other parts of the ISO 10816 and ISO 20816 series.

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