Plant & Works Engineering
A diagnosis for efficiency
Published:  07 May, 2014

Diagnostic monitoring tools are firmly established as the guardian of efficiency in engineering industries, and continue to evolve to provide ever-greater performance and functionality. Good diagnostic information from compressors increasingly ensures that problems are detected early enough to allow planned maintenance intervention or repair to be carried out with minimal disruption, says Andrew Westwood, service manager BOGE Compressors.

Machine failure, typically the result of incorrect installation and maintenance of components and equipment rather than normal wear and tear, can be easily prevented by applying advanced, but not necessarily expensive, diagnostic tools. Such tools enable efficient predictive maintenance, and the long-term reliability of countless manufacturing and process systems depend on it. Monitoring devices enable plant operators to react swiftly to impending failures within the system and therefore an effective monitoring regime is an essential part of any machine maintenance programme.

With a growing number of systems now incorporating their own diagnostic tools, companies should review the options to take advantage of the best possible options. Such is the potential saving in lost production and maintenance hours that the designers and engineers behind diagnostic tools are constantly working to improve their solutions for a marketplace eager to reap the rewards. These new products offer enhanced functionality and performance, and are extremely cost-effective.

When it comes to compressors, the increased use of electronics means that there is now an abundance of comprehensive data available to allow for efficient and effective maintenance. Good diagnostic information from compressors ensures that problems are detected early enough to allow planned maintenance intervention or repair to be carried out with minimal disruption – provided that the data is interpreted correctly. If it is, this will guarantee maximum efficiency and reliability, low service life costs and the best possible return on investment. The best of today’s diagnostic tools dispense with the need for rigidly fixed maintenance intervals and the precautionary replacement of parts by enabling status-based maintenance that cuts costs and improves investment security.

Let’s look at how this applies in practice. For example, when making investment decisions, it has long been standard practice to take into account not only the purchase price, but also the costs incurred during the service life of the machine, for maintenance and replacement parts - the Total Cost of Ownership. The goal of the plant engineer is to reduce these lifetime costs by extending maintenance intervals, while also maintaining and, wherever possible, increasing operational reliability. Innovative diagnostic tools are the key to achieving this goal. Historically, maintenance intervals were usually fixed in advance – a practice often referred to as Time-Based Maintenance - and components were replaced as a preventative measure after a specified running time. The significant inefficiency here is that the interval between maintenance is based on the average life expectancy of the parts. Why? Because only limited historical data was available, based on what had already occurred within the machine. This resulted in parts often being replaced before they needed to be, purely as a precautionary measure – and the more critical the machinery, the greater the potential inefficiency. This is because when calculating replacement intervals, the manufacturer usually incorporates a safety factor, and the greater the risk the more likely it is that important components will be scheduled for replacement before they are worn. This often results in premature maintenance and substantial costs.

However, the modern diagnostic methods offered with today’s best compressors means it is no longer necessary to replace high-value components, such as compressor stages and motors, at previously defined intervals. This results in cost savings for the customer, since the replacement intervals are increased. This offers the best of both worlds: even greater reliability at a lower price.

The increased use of electronics in compressors has also optimised switching behaviour, reducing costs and energy consumption by using intelligent control systems. The comprehensive data already available in the compressor or in a master control system can thus be collected and – after correct interpretation – can be used to provide information regarding the wear of the machinery and its components. This is particularly the case if this data is linked to additional information, such as information provided by the vibration sensors of BOGE’s newly developed “effilence” compressor stage. By monitoring vibration, the status of the rolling bearings is determined on a continuous basis. These are then replaced or renewed only when the diagnostic data indicates that this is necessary. The expensive, preventative replacement of parts is dispensed with – without increasing the risk of an unscheduled shutdown of the plant.

Monitoring can be carried out offline or online. Compressor service technicians can carry out checks using a mobile diagnostic device, checking the individual compressor to determine its status or to record events that indicate a borderline state of wear and the imminent failure of a component. Alternatively, remote monitoring allows several compressors to be integrated into a monitoring system; this offers the additional benefit of allowing early warning values to be defined. With compressor diagnostics in place, an overview of all operational compressors and treatment components can be achieved, and a flow of efficiencies will follow. Scheduling of servicing appointments is optimised, while corrections can be made during compressor operation that will ensure that the plant continues to run as efficiently as possible. With diagnostics highlighting inefficiencies and potential problems in real time, downtime is minimised and ultimately, profitability is protected.

This technical innovation also benefits the customer of the compressor supplier, as the combination of status checks and remote monitoring enables the provider to offer service and contractual arrangements that are better tailored – and more cost-effective – for the customer’s needs.

The move is towards service contracts that are better value for the user, based on a more modular concept. If customers can select the modules that are most important to them, such as remote maintenance and fault diagnostics, and add these to their service contract as additional modules without immediately having to sign a full service contract, then solutions can be tailored to the customer’s specific requirements and budget.

Thanks to modern diagnostic tools, the status-based maintenance system guarantees maximum efficiency and reliability, low service life costs due to longer maintenance intervals, more efficient use of the components and the greatest possible transparency regarding costs – in short: optimal investment security.

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