Getting Started with Condition Monitoring

So What is Condition Monitoring (CM)?

Getting Started with Portable Vibration 

Getting Started with Online Vibration


So What is Condition Monitoring (CM)? 

Let’s start thinking about machinery failures.  Machines have a number of different components that can wear out and fail, and unexpected machinery failure is expensive. It results in unplanned downtime, it can cause secondary failures to other machine components and it can create HSE (Health, Safety and Environment) risk.

So we would very much like to avoid these failures, but how do we do it? Well a traditional approach to improving machinery reliability is to carry out Preventative Maintenance (PM) based on time or hours of operation.  PM routines certainly have their place, but they do introduce expenses and risks.

Consider the example of a machine running smoothly, but “due” for a PM overhaul. Plant downtime is required to overhaul the machine. The overhaul will require labour hours, both for plant staff to disconnect the machine and workshop staff to carry out the overhaul.  Parts will be required, and functioning parts will need to disposed of. Now, these expenses are starting to mount, but there’s more.  The worst part of the PM overhaul story is that it may do more harm than good!  Once that machine has been overhauled, there is simply a higher probability that it will fail in the short term due to the overhaul than if it had been let well alone. For a variety reasons, PM overhauls can induce more problems than they prevent!

The best way to manage the maintenance of industrial plant is to use Condition Based Maintenance (CBM).  The name says it all- maintenance will be performed based on the condition of the plant, not based on running time (because running time is not a good measure of plant condition). How do we know the condition of the plant?  We use Condition Monitoring. CM is the application of measurement technologies to assess the health of machinery to enable maintenance to be carried out as efficiently as possible with the least impact on production.

 

Getting Started with Portable Vibration

A vibration program is a key tool in the condition monitoring of rotating machinery.  Data is usually collected monthly using a hand held device, as this is frequent enough to detect most defects.  For more rapidly developing defects (for example, fans that can go out of balance quickly), monitoring vibration online is required.  Very critical machinery such as turbine generators or machinery that is difficult to access manually may also be candidates for online monitoring.

When starting with a portable program, you can decide whether to do the work in-house or utilize a service provider – each has their advantages. Using a service provider can be simple and cost effective to get started. In-house programs can produce better results because staff are more available, and better placed to provide prompt and actionable advice and recommendations. On larger sites, the costs advantage of outsourcing tends to decrease.

 For smaller sites where the vibration program may consume only a few hours per week, the VMI X-Viber is an easy to use and cost effective route based vibration meter. It will allow vibration levels to be trended with data collected on a route.  For increased diagnostic capability, the vb5, 6, 7 and 8 vibration analysers plus Ascent software from GE Commtest offer the fastest data collection speed and advanced analysis and reporting tools for managing the health of your machines. The flexible range offers something to suit most budgets and machinery monitoring requirements.

 

Getting Started with Online Vibration

Online vibration offers the peace of mind that your critical machines are being monitored continuously and won’t go “bump in the night”. Online vibration starts with the LP sensor range from CTC.  These provide a 4-20mA analog signal that connects into your plant control system or SCADA system.  This allows you to trend and alarm on the overall vibration level.  Rather than using an integrated sensor/transmitter, you can instead use an accelerometer plus a signal conditioner.  This gives you more flexibility to monitor for different applications, plus gives you a dynamic signal that can be accessed for analysis.

These techniques outlined above monitor the overall vibration level.  This will not be effective for detecting all defects, particularly on more complex machines. Hence, this online overall monitoring will usually need to be complemented by periodic walkaround vibration monitoring. 

To monitor thoroughly online, we need to monitor a range of different frequencies (not just the overall level) plus we require the vibration spectrum and waveform for analysis and diagnostic purposes.  The vbOnline from GE Commtest offers this capability by collecting detailed data automatically.  It is configurable for a wide range of applications.

 

As always, if you have questions or need any advice on Condition Monitoring don’t hesitate to contact us.