Definition of Service

Compressed Air
Compressed air produces power in the form of air that is under a pressure that exceeds atmospheric pressure. The service category Compressed Air includes a myriad of applications. Examples include air operated tools (coal mining tools, drills, hammers, riveting guns, etc.), valves, and instrumentation. It can be used to turn a shaft or push a piston. The filtration of air is important as the filters remove dust and dirt that can cause wear and/or build up on the internals of equipment.

Compressed air is produced by several types of compressors including: rotary screw compressors, reciprocating compressors, and centrifugal compressors. Rotary screw compressors have rotors with very small clearances and tight tolerances that compress the air through the positive action of the rotor. Reciprocating compressors compress air in a cylindrical chamber using a piston. Air enters the chamber and the volume decreases as the piston moves inside the chamber, thereby compressing the air. A centrifugal compressor is a dynamic compressor that compressors air by the mechanical action of rotating impellers or vanes. The impellers or vanes impart velocity and pressure to the air.

Dust Collectors
Dust Collectors are filters utilized to remove airborne particulate matter or nuisance dust that may have been generated by a manufacturing process. Dust collectors are also frequently used as powder recovery filters in a wide range of dry chemical production processes. Examples include:

Nuisance Dust Control

• Woodworking sawdust and sanding dust
• Welding fumes and smoke
• Metal grinding dust
• Plasma arc cutting
• Foundry sand dust
• Gas turbine inlet air

Process Powder Recovery

• Pharmaceutical dusts
• Food dusts
• Dry chemical dusts

Dust collectors are available in three (3) basic configurations:

• Cyclones
• Bag Houses
• Cartridge Collectors

Cyclones are conical shaped vessels that utilize centrifugal force to separate heavier dust particles from the air stream. Cyclones typically operate in an efficiency range of 60% to 95%.

Bag houses are large filter housings fitted with multiple filter bags or pleated elements. Dust laden air is pulled through the bags. A dust cake forms on the outside of the bag and clean air flows out of the center of the bag. Bag house filtration efficiency will range from 90% to 99.95%. Cleaning of the bags is accomplished with reverse air pulsing, reverse airflow or bag shaking.

Cartridge collectors utilize pleated cartridges to filter dust from the air stream. Cartridge collectors offer very high efficiencies in the 99.9% to 99.999+% range. Cartridge media is typically cellulose, polyester or cellulose/polyester blends. Membrane laminated cartridges are frequently used in very fine dust and/or medium temperature (below 400ºF)(204ºC) applications. The cartridges are cleaned with a reverse pulse of compressed air.

Cyclones are frequently used in series with either a bag house or cartridge collector. The cyclone will efficiently remove the heavier particles and reduce the load on the bag house/cartridge collector. This will help prevent blinding of the bags or cartridges and reduce the cleaning cycle frequency.

Fuels
The service category "Fuels" includes hydrocarbon liquids used as fuel for engines or industrial burners. Typical examples of fuels would be diesel fuel, gasoline, jet fuel and kerosene.

Filtration of fuels is important, because no matter how carefully they are handled, contaminants are introduced into the fuel during transfer, storage and normal operation. Water, one of the greatest enemies of fuel, is readily introduced into the fuel storage containers as condensation from the air during normal daily heating and cooling cycles. The presence of water in fuel causes iron components to rust, thereby forming even more contamination. At the interface of water and diesel fuel, for example, microbiological growth occurs rapidly and presents yet another contaminant that can clog a fuel delivery system.

The presence of water in fuel, particularly at cold temperatures, makes the fuel more viscous. At freezing temperatures, ice crystals can form in the fuel that could block a fuel line. Aircraft are very susceptible to fuel line freeze-up and must use fuel that is virtually water-free.

Aircraft ground support vehicles are equipped with coalescers that remove water to API 1581 standards. Diesel operated trucks and tractors usually use separators that remove free water from fuel prior to particulate filtration.

For efficient operation of engines and burners, fuels need to be filtered to remove damaging water and particulate contaminants.

HVAC
HVAC filter systems are used to control a broad spectrum of environmental contaminants. These systems use a wide variety of filter configurations, sizes, and media. HVAC systems are designed for all buildings that are heated, ventilated, and/or cooled, but special consideration is required for microelectronic facilities, pharmaceutical facilities, hospitals, special government facilities, power generation plants, and paint booths.

Hydraulic/Lubrication
The Hydraulic/Lubricants service category includes industrial oils, hydraulic oils, greases and hydraulic and lubrication equipment. For example, typical industrial hydraulic oil would include MIL-H-5606 red hydraulic oil.

Hydraulic fluid basically performs four functions:

• Transferring force to motion in a hydraulic circuit
• The hydraulic fluid fills the spaces between the metal surfaces thereby providing a pressure barrier that helps prevent contamination ingression
• The hydraulic fluid provides a lubricating film between the metal surfaces
• The hydraulic fluid cools the system components

Hydraulic fluid performs best when it is free of air, water, and particulate contamination. Proper filtration can remove particulate contamination and limited amounts of entrained water. Large volume water contamination can be removed by centrifuging, coalescing and vacuum distillation. The latter is the only process that can remove water to the 10-ppm range.

Lubricating oils and greases provide a thin lubricant film to prevent metal-to-metal contact between moving components. Filtration of lubricating oil is required to remove particulate contamination that could compromise the lubrication film effectiveness. Even new, drummed lubricating oil should be filtered to remove "built-in" contamination. Water contamination is often overlooked when determining a system's filtration requirements. Water can cause as much damage as particulate contamination. This is particularly true for bearing lube applications.

Clean, water-free oils and lubricants perform best and last longer than contaminated oils. Maintenance costs are reduced considerably when fluid cleanliness control programs are instituted and maintained.

Intake Air
Intake air filters prevent atmospheric dust and other contaminants from entering the air system. This protects the equipment from internal damage and excessive maintenance and increases the efficiency of the equipment. Proper intake air filter selection depends on airflow and airborne dirt or dust loading. Intake air filters are used on a variety of equipment types, such as air compressors, aircraft, and locomotives.

Liquid/Water
The "Liquid/Water" service category filter applications include:

• Process water used in manufacturing plants
• Liquid chemicals
• Potable water
• Beverages
• Petrochemicals

The exception is hydraulic fluid, hydrocarbon fuels and lubrication fluid such as grease, which are categorized under Hydraulic/Lubricant.

Process Gases
Process gases include industrial gases, such as:

• Natural gas
• Propane
• Nitrogen
• Carbon dioxide
• Steam
• Specialty gases like helium and argon

A process gas is filtered to remove contamination from piping, water, oil or other contaminant that could impede the operation of downstream instruments or equipment.

Some gas applications require that moisture and oil vapor be removed. In these cases, a pre-filter would be used to remove particulate contamination prior to a coalescer that removes water and water vapor. If the process gas needs to be very dry a desiccant dryer can be used to obtain a dryness of up to -100º F. Removal of oil vapor and odors is accomplished by the use of an activated carbon filter.

Depending on the application, steam is filtered to remove particulate contaminants, pipe scale, and microorganisms.

Smoke/Oil Mist
Smoke/Oil Mist is the removal of small particles of oil and water in aerosol form from manufacturing processes and lubricated compressed air systems. These filters eliminate sub-micron particles, ideally with a very low pressure drop, low fluid velocity, and long dwell times. If the mist is not removed, the particles may cause increased operating costs, equipment corrosion and fouling, product contamination, and damage to instrumentation.

The mist can be formed through cooling and the accompanying condensation of a gas stream, a chemical reaction within a process, or when mechanical forces atomize an entrained liquid. The particles formed through chemical reactions and cooling and condensation are typically submicron size. The particles formed via mechanical forces are typically larger particles.