In the previous post, we outlined some of the considerations for selecting either a reciprocating or rotary scroll air compressor. One of the major considerations will be the routine maintenance, which in turn will affect the “Cost of Ownership over a specified period of time”.
Maintaining Oil-less Air Compressors, Reciprocating and Rotary Scroll
Both reciprocating and oil-less air compressors require very little maintenance. The following items are basic requirements for either type of compressor.
- Air Intake Filter: It is a basic concept that in order to compress air, you must be able to intake air to the compression chamber. Air intake filters protect the compressor from ingesting contaminants that may cause cylinder and piston ring wear or damage, or cause intake and discharge valves to malfunction. As the filter becomes restricted by contaminants, the compressor will lose capacity. Depending on the cleanliness of the location, and the amount
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There are several types of oil-less air compressors available on the market, and the selection of a compressor will usually be determined by the application’s volume and pressure requirements, and in some cases, how and where the air will be used. The industry has changed over the past 50 years, and going back to times prior to the 1970’s, most oil-less air applications for standard pressure (up to 125 PSIG) were serviced by reciprocating air compressors. For large industrial applications, these compressors were available in the single stage (for pressures to approximately 100 PSIG) and 2-stage machines (pressures above 100 PSIG). For high volume applications, these machines were usually massive, with cast iron frames, and were water cooled by way of cooling jackets in the compression cylinders and heads. Most of these machines were double-acting (compressed air on both the upstroke and down-stroke of the piston) using a … Read the rest
Air burst systems are a standard requirement for municipalities and industries that draw water from rivers, lakes or ponds. The air burst system is designed to keep intake screens below the water level clear of debris and silt which accumulate as a result of inward water flow. The basic principle is to displace these materials with a high volume blast of compressed air in reverse flow direction through the screens. The systems are normally designed to be automatic and operate on a timed basis, calling for an air burst usually once or twice a day, or as required/established, depending upon the intake water conditions. Some basic calculations must be made to determine the volume of air required (relative to the screen size), air storage receiver size, and piping and air burst valve size based on air volume and distance from valve to screen. A good control design will allow the … Read the rest
Air Power Products Limited has been supplying our “Purge Economizer Control$” systems for over 25 years. The original intent was to supply our customers with a system that not only save compressed air, but would also indicate what those savings amount to. The second initiative was to provide these features at a reasonable cost that would provide a quick ROI for the user. That was 25 years ago! Today the issues of saving compressed air is of even greater importance as the cost of electrical services rise. Not only are these issues recognized by compressed air users, but they are also recognized by the utilities that provide the electrical services. Our price for this control system over the past 25 years has remained very consistent and price competitive.
We have recently added some user beneficial options which, although they increase the cost of the control system, can be easily offset … Read the rest
When it comes to proper desiccant dryer performance one of the most common culprits resulting in poor dew point performance, is lack of prefilter maintenance and/or faulty prefilter drain operation. Most oil coalescing prefilter elements should be replaced at 2000 hours of service. Without a disciplined PM schedule to replace these elements and to confirm proper prefilter bowl drain operation, you run the risk of contaminating the desiccant bed.
Manual drain valves on the bottom of these filters are often problematic when not drained in a timely fashion, allowing oil to re-entrain into the airstream, causing oil to enter the desiccant chamber. Float type drains (internal or external) must be checked for correct operation as they may become fouled with oil/water emulsion and fail to operate properly. Electronic solenoid auto drains complete with off/on settable timers are most favorable when used with a strainer, as they allow periodic draining to … Read the rest
When it comes to properly sizing a dryer, there are some misconceptions that often lead to incorrect, or over-sizing of a compressed air dryer.
Most people charged with the responsibility of designing the compressed air system or installation of a correctly sized air dryer, typically match the inlet capacity with the compressor maximum output. This is especially incorrect when sizing for an air-cooled reciprocating air compressor. Reciprocating air compressors are typically air cooled, and use pitched vanes on the pump flywheel which drive cooling air across finned cylinders to allow/assist in the air cooling and heat dissipation. These pumps are typically designed for a maximum duty cycle of between 50 to 75%.
If the duty cycle of a compressor that produces 20 CFM is 65%, then the maximum output or constant should be based upon no greater than 13 CFM, therefore the matching dryer size would only require 13 CFM … Read the rest
Lubricated reciprocating air compressors, like an automobile, require regular oil changes to ensure that bearings and piston skirts are receiving clean lubricant to prevent metal to metal contact. Most small reciprocating compressor manufacturers recommend oil changes every 12 months or 500 hours – whichever comes first. Many small reciprocating air compressors may operate on single phase power directly fed by a breaker. Three phase models may use an economically priced off-the-shelf magnetic motor starter. In both of these scenarios, there is usually no provision made to log hours on the compressor.
The Problem with Start/Stop Air Compressors
The problem with compressors operating on a start/stop basis, is that the user usually has no idea of the actual hours that accumulate on the air compressor. As a result, oil changes are often neglected, or allowed to run past the due date. This may result in excessive wear causing reduced life … Read the rest