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Compressor Airend Replacement, Overhaul, Rerate/Derate - Which Solution Is Right for You?

Air Compressor Needs an Overhaul Air Compressor Overhaul

Flawless airend performance is essential for a centrifugal air compressor to run efficiently. Over time, like any other highly engineered equipment, airends may require servicing or replacement. There are a few different options to consider when this time comes. 

Depending on your unique situation, airend replacements, overhauls, and rerates/derates can all serve as valuable solutions. Understanding the differences between these options can help you make the best decision to suit your specific requirements.

Airend Replacement

A replacement airend is simply ordering an entirely new airend instead of servicing or upgrading the existing one. The replacement is designed to the same specifications of the original airend.

Airend Overhaul

An overhauled compressor airend has its components restored to the original OEM specifications. Benefits include extending the life of your compressor, bringing vibration levels back in line with OEM standards, and increased longevity of moving parts within the airend core. 

Airend Rerate/Derate

Over time, your plant’s needs may have changed-- requiring more air than the initial airend design can supply. A rerate would reexamine the existing components and make aero adjustments to achieve the new demand. In doing so, design flow, design discharge pressure, and efficiency can be increased.  Centrifugal compressor performance can be improved by as much as 30 to 50%. 

With demand changes, there is also a possibility that a derate is in order. When a compressor is too large for a given application, the unit may consume more energy than necessary, resulting in increased utility costs. Derating airend components can better align your compressor with your current needs. In addition, a derate can be used to turn the original compressor into a trim machine to utilize in times of increased demand.

Making the Decision

All of the above solutions-airend replacement, overhaul, or rerate/derate-are viable options to utilize your maintenance budget, avoiding a larger capital expense, while keeping in step with your current air compressor needs.

In many cases, the best choice may not be immediately clear. The first step is to obtain a budgetary proposal from your authorized FS-Elliott Channel Partner or representative. With an overhaul, after the tear-down and inspection, a complete report and a firm proposal will be provided. Typically, a replacement airend proposal is provided along with the overhaul proposal, so all options are understood upfront.

A third-party air audit can also be utilized to determine if a rerate, derate, or new compressor is the best solution to meet your current needs. 

Furthermore, in some cases, a combination of these solutions should be considered. For example, you may choose to purchase a replacement airend but still get the original airend overhauled to keep as a spare. Having an extra airend onhand would minimize downtime on a compressor by eliminating manufacturing lead time. 

There are many factors to consider, so it’s not a one size fits all. For more information on airend replacements, overhauls, and rerates/derates and how these options might assist you in maintaining flawless airend performance, contact your authorized FS-Elliott Channel Partner or Representative today!

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