Compressed air is the fourth utility. It is just as vital as water, gas, and electricity in today's industrial and aircraft maintenance operations. It runs tools and machinery, applies paint and coatings, and if properly designed can even ensure clean, breathable air in contaminated environments.
When purchasing a compressor or compressed air system, there are several factors to consider including the total cost of producing compressed air, the specific compressor features, maintenance requirements, and product warranty. Remember that the most cost-effective unit is not usually the lowest priced. Reliability and efficiency are key. An unreliable compressed air system can be disastrous to the bottom line.
Consider the following factors when evaluating your compressor options:
Electrical expense: As much as 70 percent of compressed air cost is electricity to operate the compressor. Look for a compressor that offers the most air per electrical consumption. Look at the package efficiency and check with the manufacturer for engineering data. Members of the Compressed Air and Gas Institute (CAGI) will publish their data on official CAGI data sheets so that compressor efficiencies can be easily and accurately compared.
Installation: Consider noise and vibration when choosing a compressor. Compressors that do not require special rooms or custom foundations will save on installation costs. Many units available on the market today can be purchased as package units with integral dryers and filtration, or tank mounted to minimize the system's space requirements.
Maintenance and repair costs: The easier the system is to service, the more you save in the long run. If either in-house personnel or contracted professionals can easily and properly maintain the air system, overall operating costs and downtime may be reduced. Proper maintenance increases an air compressor's reliability and efficiency. A compressor that is difficult to service may not receive adequate preventive maintenance, possibly resulting in costly repair and downtime. Some air compressors and air compressor components are specially designed for easy maintenance and repair.
Components to evaluate in a compressor include:
Cooling systems: Coolers and fans must be sized to provide low discharge temperatures in high ambient temperatures. In air-cooled units, low noise radial fans generally provide better cooling while using less electricity than axial fans. Also consider the ability to easily duct air in and out of the compressor package. Topside exhaust often simplifies ducting and reduces footprint.
Drive: Drive efficiency and simplicity are important. Belt drives require only simple maintenance and offer advantages such as flexibility in pressure selection. Automatic belt-tensioning devices are a must to ensure transmission efficiency and protect bearings from excess stress. Larger facilities with large air requirements may see additional advantages with recent direct drive technology. True direct drive units -- ones without gear connections -- offer the best efficiency with no loss in transmission efficiency and no maintenance requirements.
Operator interface: The control panel must be reliable, readable, and run the compressor efficiently. It should indicate operational status as well as offer maintenance interval reminders, diagnostic information, and external communications capability for remote monitoring and control.
Interconnecting piping: Look for rigid piping with flexible connections and high quality fittings to eliminate leaks.
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