GAOTek Pen Type Vibration Meter (Max Hold Fn, High Accuracy)

Additional Information

Applications

• Used for measuring periodic motion, to check the imbalance and deflecting of moving machinery.
• Specifically designed for measuring various mechanical vibration
• Provides the data for the quality control, run time and equipment upkeep.

Standard Package

Introduction to Vibration Measurement

Vibration is a reliable indicator of the mechanical health or condition of a particular machine or product. An ideal machine will have very little or no vibration indicating that the motor, as well as peripheral devices such as gearboxes, fans, compressors, etc., are suitably balanced, aligned, and well installed. In practice, a very high percentage of installations are far from ideal, the results of misalignment and imbalance exerting added strain on supporting components such as bearings. Eventually this leads to added stress and wear on critical components, resulting in inefficiency, heat generation and breakdowns.

This often occurs at the most inconvenient or uneconomical times, causing costly production downtime. As parts of mechanical equipment wear and deteriorate, the equipment vibration increases. Vibration measurement is therefore a powerful aid in the predictive maintenance of such equipment, reducing downtime and assisting in the smoother running of the plant or factory. Unscheduled breakdowns result in production losses and the faulty equipment is usually repaired hastily to get production going as quickly as possible. Under these stressful conditions, staff is not always able to do repairs correctly regardless of how conscientious they are, resulting in a high probability of further early equipment failure. By implementing a predictive maintenance program with regular measurements of critical factors like vibration, downtime can not only be reduced, but planned maintenance is more effective, resulting in improved product quality and greater productivity. Continuous monitoring and trending of vibration levels over a time period is therefore a valuable addition to a machine’s historical record.

Trend

A trend is an indication of the way in which a monitored vibration parameter behaves over time. If regular vibration measurements are taken and plotted over a period of time, the resulting graph shows the progress or deterioration of a particular machine. Typically this will have the general shape shown in the diagram below, regardless of the type of machine being considered. For a short time after installation, whether it is a new or a repaired machine, vibration levels may fall slightly as the machine is run in, followed by a long period of unchanging levels during the machine’s normal operating lifetime. Then comes a period of rising levels as the machine parts wear out and ultimately lead to failure. Such a trend enables the maintenance engineer to predict the time of failure and maximize use of the machine, while ordering spares and planning its maintenance for a time convenient to the production schedule.

Front Panel Description

1. Debugging aperture
2. Power key
3. Accelerometer probe
4. Charger interface
5. RS232C interface
6. Display

 Measuring Procedure

1. Depress the Power Key and release to Power on the meter.
2. Press the probe onto the tested surface vertically
3. Parameters including Displacement, Velocity and Acceleration are displayed.

MAX HOLD Function  

1. Depress the Power Key and release to power on the meter.
2. Press the Power Key again, the ‘MAX’ symbol is displayed, representing entering the Max Hold Mode. The reading on the display is the max value during measuring.
3. To quit the Max Hold Mode, just press the Power Key once more.

Metric/ Imperial Conversion

1. Depress the Power Key and release to power on the meter.
2. Depress the Power Key and do not release it until the ‘UNIT’ symbol is displayed. The unit will be converted between Metric and Imperial.

 Considerations

Parameters to be Measured

Acceleration, Velocity and Displacement are the three tried and tested parameters, which give accurate and repeatable results. Other measurement parameters have yet to prove themselves to be as reliable, accurate, and repeatable.

Acceleration: is normally measured in 2 m/s peak (meters per second squared) has excellent high frequency measurement capabilities, and is therefore very effective for determining faults in bearings or gearboxes.

Velocity: is the most commonly used vibration parameter. It is used for vibration severity measurements in accordance with ISO 2372, BS 4675 or VDI 2056, which are guidelines for acceptable vibration levels of machinery in different power categories. Velocity is typically measured in cm/s RMS (centimeters or millimeters per second).

Note: This instrument measures in cm/s. If you are more familiar with measurements in mm/s, or wish to compare your measured values directly with the vibration severity chart in section 4, multiply the displayed value by 10.

Displacement: is typically used on low-speed machines because of its good low frequency response, and is relatively ineffective when monitoring bearings. Units are typically microns or mm equivalent peak-peak.

 Vibration Standards

Rank of machine vibration (ISO 2372)

 Note:

1. Class I is small motor (power less than 15 kw). Class II is medium motor (power between 15 kw ~ 75 kw). Class III is high power motor (hard base). Class IV is high power motor (stretch base)
2. A, B, C, D are the indicator of vibration rank. ‘A’ means good, ‘B’ means satisfying, ‘C’ means not satisfying, ‘D’ means forbidden. Vibration velocity should be taken from the three perpendicular axes on the motor shell.

ISO/IS2373 Motor quality standard according as vibration velocity

Limit of rank ‘N’ is suitable for common motor. When the request is higher than that in the table, limit can be obtained by dividing the limit of rank ‘S’ with 1.6 or multiples of 1.6

Maximum vibration of motor that power larger than 1 horsepower (NEMA MG1-12.05)

 For AC motor, rev is maximum synchronous rev. For DC motor, it is maximum power rev. For motor in series, it is work rev.

Maximum vibration of high power induction drive motor (NEMA MG1-20.52)