Machines are like people. They all have certain similarities, but are different in many ways. Two exact machines in the same operation may perform and respond quite differently.
Setting alarm values for your vibration measurements is critical for the success of your vibration monitoring program. Alarms will help the analyst identify when conditions on the machine have changed and assist in identifying specific fault conditions. All of this makes the analysis much more accurate and easier. Additionally, this can reduce the amount of time required to analyze the vibration data collected. However, for all this to work the alarms must be set up correctly.
The question becomes what alarm values do you use? Determination of alarm values is especially difficult for the inexperienced analyst, or when no historical data is available for the equipment. Many sources have published generic alarms based upon specific equipment types and operational speeds. These published alarms can be very valuable in certain circumstances. However, as stated previously, machines are like people and are different in their performance and responses. The best method is to collect data on the equipment for a period of time and set statistical alarms for each machine based upon its unique operating characteristics, performance and type. This method will always provide the best results for your vibration program and increase the accuracy of your analysis.