Finding the right balance between performing service often enough and performing service too often can be an inexact science. Separators and decanters require regular maintenance to eliminate system failures. But unnecessary service brings unnecessary expense. Condition-based maintenance and vibration analysis are one way of accurately predicting maintenance requirements to optimize service intervals for separators and decanters.

A predictive and proactive approach to maintenance for separators and decanters can eliminate both unplanned production stops and unnecessary service costs, thus providing more efficient and more cost-effective operation as well as:

• Higher return on investment due to longer machine life;
• More accurate service planning and personnel allocation;
• Better management of spare-parts inventory;
• Increased safety.
• The challenge, however, is finding a way to predict maintenance needs accurately at the right time.
• Accurate Prediction
• The core control system from Alfa Laval is a powerful tool that can help companies predict maintenance needs accurately and thereby get the most out of their equipment.

The system can analyze vibrations, temperatures, pressures, and so on, in the separator or decanter to establish the status of all its major rotating components and determine how the machine is performing. Continuous measurements take place automatically during normal operation, so no extra time is needed for monitoring. The system then calculates the optimal time of service through careful analysis of the machine status. So, corrective action can be taken before components break down. A central component of the core control system is vibration analysis.

Why Measuring Vibration?

Measuring vibration is the best way to determine the status of the rotating components in a separator or a decanter. Vibration is the natural response to internal and external forces of any machine in operation. Under normal operating conditions it occurs in a very predictable fashion. When an error occurs, however, new forces alter the normal vibration. This difference can be examined and the information used to understand what is happening with the machine. This allows to pinpoint exactly when and where maintenance is needed.

The Way Measuring Works

In addition to temperature sensors, speed sensors, load sensors and so on the core control monitoring system includes a number of vibration transducers. To measure vibration, the transducers are mounted at specific points on the machine. Vibration is converted to an electrical signal, which is measured and analyzed by proprietary monitoring software.

Determine Normal Vibration Data

By ensuring that the specific frequency range and the measuring point are consistent when examining machines of a given class, limit values for the vibration energy normally generated by a specific symptom could be determined. The core control system applies statistical methods to pinpoint usual variations of a specific vibration parameter coming from a certain machine type.

Diagnose Errors Accurately

A single measurement generates a complete picture of the condition of all the rotating parts. Errors are diagnosed by identifying sources in which the condition has deteriorated beyond acceptable limits. Parameters and color-coded symbols depict the unit's current operational status based on the data gathered through monitoring. This information is invaluable for accurately predicting maintenance needs and scheduling appropriate service.

Real World Example

The core system vibration monitoring was tested on a high-speed separator at a brewery in the U.S. in 2006. It reported an acute spindle bearing condition on July 8, 2006. This particular spindle cartridge had been in service since December 2001. The system diagnosed the abnormal condition and identified symptoms from outer ring damage and ball damage on upper top bearing. Replacement of the spindle cartridge was recommended. Because the system provided an early warning, service was scheduled for a time when the penalty for stopping production would be minimal. The spindle cartridge continued to operate for another two weeks. The cartridge was replaced during scheduled maintenance on July 21. Upon replacement, the cartridge boasted more than 40,000 hours of service.

Report Confirms Damage

All four bearings were sent to the bearing manufacturer for investigation. A report from the manufacturer confirmed the indications outlined by the core control monitoring system. In particular, it showed that upper top bearings were damaged by spalling and had been in service longer than its service life. Spalling was found on one ball and on two spots of the outer ring. Corrosion was found on almost all surfaces.

Take Control

The core control monitoring system, including vibration monitoring, has been used in many applications such as pharmaceutical, power, waste treatment, and food. Through accurate prediction of maintenance needs, it allows companies to take control of their service schedules. This leads to improved performance and reduces un-scheduled downtime for more effective, more cost-efficient use of separators and decanters. A user of Alfa Laval's condition-based maintenance program states: "We save a lot of money by utilizing condition-based maintenance since we no longer run our machines to the point of breakdown. We can also plan maintenance in a completely different way. The result is minimized interruption in production. The money we earn due to better availability of our machines is even more than our savings on reduced breakdowns."