Much of the conversation about compressed air is about the air coming from a compressor, but the conversation about air flow going into a compressor is often neglected. If an air compressor isn't fed by a source of clean, cool air, then it will suffer in terms of performance, economy and reliability. Below are two areas that should be addressed to ensure the air quality entering your compressor is optimal:
Before even considering equipment needs, the first task is to identify an appropriate location where your compressor draws air. In a typical scenario, fresh air is drawn from its immediate surroundings through the intake filter and into the compressor. However, the air quality is often far from optimal in the vicinity of a compressor, and the inlet should be extended some distance; below are the qualities of high-quality intake air:
Air increases in density as its temperature drops. Dense air entering a compressor gives it a "head start" by reducing the amount of work that needs to be done to compress air. From a practical standpoint and with all things being equal, the cooler the air entering the compressor, the better performance you will achieve.
You should seek to place air inlets in a location away from hot equipment, steam pipes and other areas where heat build-up is common. Ideally, you need to have two air inlet sites that can be switched from one to the other with the turn of a valve. One inlet should be located outside so it draws cold air in winter, and the other may need to be placed in an indoor location during summer so it can draw cooler interior air.
Air entering a compressor should also be as dry as possible. Moist air is less dense than dry air, and the water can corrode compressors and downstream components as well as contaminate products. To combat the problem of moist air, place compressor inlets where they aren't exposed to high levels of moisture; keep air inlets away from cooling towers, gutter downspouts, vegetation and other moisture-rich environments.
Preventing the inflow of dirty air is another key to preventing premature failure of your compressor and keeping quality control problems at bay. To accomplish this, air inlets should be placed where they will not draw soil particles, gravel particulates, sand, and other microscopic contaminants into the compressor. Keep inlets away from roads, conveyor systems and areas of construction.
The intake of cool, dry and clean air is not easy to achieve, especially when you consider that compromises may not permit a perfect solution for inlet placement. Since at least one of the above parameters will probably not be satisfactory, that makes the addition of an inlet air filter a more urgent need. Even if you believe your inlet environment is nearly perfect in all dimensions, you are taking a potentially expensive risk should you omit an inlet filter on your air compressor.
When choosing an inlet air filter for your compressor, there are a few considerations that should be made for the most efficient operation of the unit. Here are a few factors to keep in mind:
- Filter size – air inlet filters are usually cylindrical with an inner tunnel surrounded by filter media. These come in various sizes depending on the size of your compressor. Always choose a filter that matches your air compressor's capacity and pressure rating. A filter that is too small for your compressor will cause a pressure drop that makes the compressor run erratically and lowers your air output pressure.
- Particulate and water drains – some filter housings contain a drain for solid particles trapped inside the housing and a drain to tap accumulated water. These can be useful in extending the life of your filter. However, in all instances, filters should be regularly checked and cleaned to keep them operating at maximum efficiency.
- Replacement schedule - Filters should also be replaced periodically according to the manufacturer's recommended schedule; trying to "nickel and dime" yourself by using a dirty, worn-out filter will cost you more in increased operating expenses than the few dollars it costs for a replacement.
- Particle size – all filters are rated in terms of effectiveness. They are usually assigned a percentage value, such as 99.9 percent, that measures how many of the passing particles are captured. Be cautious when choosing by percentage alone; even a miniscule drop in percentage effectiveness can mean a dramatic decrease in the filter's ability to capture particles.
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