Corporate Buyers Guide

Air coming out of a compressor is in the 200 F to 400 F range depending on the output air pressure. Since it is hot and compressed, the air will contain a lot of moisture. Before the air can be used, the temperature has to be lowered. An after cooler is the first step and is usually mounted right at the output end of a compressor.

After coolers can use either air or water for the cooling. Air cooled models can reduce the temperature of the compressed air to about 30 F over room temperature. To do this, the after cooler requires a lot of space for the hot air to dissipate without affecting surrounding equipment.  Water cooled after coolers can get the temperature lower, to about 40 F absolute, however, they require a lot of water.

During the cooling, most of the moisture in the air condenses and has to be drained from the system. This is usually done by collecting the water in a trap which periodically drains the water to the atmosphere.

Bag dust collectors are most common for high volume air filtration in industrial applications. The air flows into the inside trapping the dust on the inside. The bags are usually mounted so that the air flows upward into the bag. With periodic vibration, the trapped dust particles fall downward into containers placed under the collector. The bags come with removal efficiencies from 35 to 95% depending on the size of dust particles and the porosity of the fabric. The minimum particle size for bag filters is around 5 micron. For special applications 1 micron bags are available, but they usually are for secondary, or after filter applications. .

The air flow capacity of the bag dust collector is determined by the fan design and power in Hp plus the area of the filter media. As particles collect on the filter surface, more air pressure is needed for the air to flow. The pressure drop from the input to the output of the filter affects the amount of air flow. The flow capacity listed is for most models at a 4 inch water pressure drop