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Experienced vibration analysts or reliability leaders who have spent considerable time managing a vibration program can tell you just how important alarms can be. Those who embrace the concept of using alarms will find themselves catching defects more efficiently, saving valuable time, and enjoying their job. Those who neglect alarms will find themselves overworked and overwhelmed.

What is an alarm?

An alarm consists of predefined thresholds that warn us when vibration amplitudes or other parameters exceed acceptable limits. A good vibration program will have a group of alarms that are used to assist the analyst in determining which machines are okay. Furthermore, they can also tell us which machines may need some attention or even shut down!

Some vibration data collectors and software systems will allow the analyst to assign colors to each alarm stage. That said, the most basic way to put this would be “Green machines–good” and “Red machines–bad”. This may seem very straightforward for now, but it does get a bit more complex from here. Let’s cover a few things to watch out for when creating these alarm thresholds and establish some best practices for using alarms in your program.

Route-Based vs. Continuous Monitoring

The way alarms are applied and managed will vary significantly between route-based programs and continuous monitoring. After all, these two types of programs are drastically different in their entire process.

Route-Based Alarms:

Alarms in a route-based program are primarily put in place to draw the analyst’s attention to certain machines. Often, if alarms are set properly an analyst can assume that any machine that is not in alarm can be skipped over and considered good. By the same token, machines that are “in alarm” will need to be analyzed to determine the reason for the alarm.

Alarms in a route-based program are also extremely helpful when it comes to generating reports. Most vibration analysis software programs will contain some kind of site status report that depends on alarms to categorize machines. These alarm status reports are extremely handy for an analyst to deliver to his supervisors or planners who only want an overview of the condition of the plant’s rotating assets.

Continuous Monitoring Alarms:

Alarms may be the most advantageous when implemented into a continuous monitoring program. A good continuous monitoring program has the functionality to send notifications through email or SMS messages. This provides huge advantages for machine owners, analysts, reliability leaders and any other team members that are set up to receive such notifications.

In a continuous monitoring program, alarms can be set in place to alert an entire team the instant a machine or bearing goes into alarm. This immediate notification method can dramatically reduce unplanned downtime. We don’t need to wait three weeks for the analyst to run his route again and another two days for analysis and reporting to be completed.

Continuous monitoring systems also give us the ability to trigger alarms on multiple technologies simultaneously. For example, a machine that is being monitored with wireless vibration sensors can often provide alarms for vibration, temperature, rpm, and more. These alarms notifications occurring in certain combinations at one time can tell a very particular story.

The most successful vibration programs use a blend of route-based and continuous monitoring strategies, incorporating alarms into both.

What parameters can alarms be set on?

When people think of vibration alarms they typically think only of overall vibration amplitudes. While that parameter may be the most common alarm, there are a multitude of other useful values we can alarm from. Here are a few examples to consider:

• Velocity RMS- Overall
• Acceleration RMS- Overall
• Displacement Peak or Peak-to-Peak
• Peak Acceleration (Max Peak)
• Temperature
• Powerbands
• Crest Factor
• Kurtosis
• RPM
• Manual Entries (Current, Flow, Pressure, Load etc.)
• Envelope Values

As you can see, alarms can become extremely beneficial to a program. To go a step further, there are several alarm parameters that can be used in a continuous monitoring program to warn of issues with the monitoring devices themselves. Here are a few examples of those.

• Battery level
• Signal strength (Sensor to Receiver)
• Signal strength (Receiver to Outside World)
• Ambient Temperature
• Sensor Temperature
• Machine Temperature
• Receiver Online Status (Power Loss)
• Sensor Online Status

As technology continues to advance, the list of parameters that we can use for an alarm strategy will continue to grow.

Conclusion

Now that alarms have been defined, be sure to check out the second part of this series to learn practical tips on setting and maintaining alarms.

Vibration Alarms Save Time!