1. Pneumatic System Conditioning
Chapter 12
Pneumatic System Conditioning
Pneumatic System Contaminants • Pneumatic Filters • Pneumatic Conditioning Devices • Compressed Air Preparation Procedure

2. Common forms of pneumatic contaminants include dust particles, moisture (water droplets), and lubricating oil from the air compressor.
Contaminants in a pneumatic system are similar to those present in a hydraulic system. A contaminant is any foreign object in the air of a pneumatic system. Solid contaminants, such as dirt, dust, and pipe scale, can be introduced through pipes or other pneumatic components. Liquid contaminants, such as moisture and crankcase oil from the air compressor, can also be entrained into the air. See Figure 12-1.

3. The total amount of moisture that air is capable of holding varies based on the temperature of the air.
Water vapor condenses once the air sufficiently cools. Dew point (saturation temperature) is the temperature at which the moisture in the air begins to condense. See Figure Typically, the atmospheric air that is used by an air compressor is not saturated because it does not contain visible moisture. However, since humidity changes from day to day, atmospheric air should still be tested before a conditioning plan is specified. Any form of water that is trapped in a pneumatic system can destroy equipment, contamin- ate product, or lower equipment performance.

4. When air is compressed in an old and worn air compressor, oil can be discharged into the system.
Oil contamination in a pneumatic system may occur from overlubricating the air compressor. An air compressor must be lubricated with crankcase oil in order to reduce the friction between internal moving parts. When air is compressed, it collects some of the crankcase oil and can carry it in the form of oil vapor into the system. See Figure 12-3.

5. An intake filter removes contaminants from the air before it is pulled into the air compressor.
An intake filter is a pneumatic filter that is used to remove contaminants from air (typically atmospheric air) before it travels into the inlet of the air compressor. See Figure There are two locations for intake filters that are typically used. One location for the intake filter is to directly attached it to the air compressor intake. The advantage to this location for the intake filter is that little or no piping is required. The disadvantage is that the environment where the air compressor is located can contain solid and chemical contaminants, and the air is typically much warmer than the outside air.

6. Inline filters are used to filter contaminants that have collected in a pneumatic system.
Contaminants can be collected in the compressed air as it travels throughout a pneumatic system. An inline filter or separator is used to filter out the collected contaminants. An inline filter is a pneumatic filter that removes contaminants from within a pneumatic system. Inline filters include an inlet port, an outlet port, filter housing, a baffle, a filter element, and a filter screen. See Figure An inline filter operates through the following procedure:
1. Air enters the inline filter and is forced downward by the baffle. This forces the air to rotate within the filter housing.
…Complete procedural list on pages 382–383.

7. A surface-type filter element allows compressed air to flow in a straight line through the filter and collects contaminants on its edge.
A surface-type element is a pneumatic filter element that allows compressed air to flow through the filter in a straight line to collect contaminants on its surface. See Figure The surface that collects the conta- minants must always face the airflow. Surface-type elements are usually constructed of treated paper.

8. Coalescing filters remove submicron solids, water vapor, and oil vapor by combining small droplets into larger droplets.
A coalescing filter is a device that removes submicron solids, water vapor, and oil vapor by combining small droplets into larger droplets. Coalescing filters are sometimes referred to as inline liquid filters. Coalescing filters should be installed as close as possible to the point of work. See Figure 12-7.

9. Intercoolers are used to remove a portion of the heat of compression as the air is piped from one stage of compression to another.
Heat generated in a cylinder of an air compressor is removed by conduction through the cylinder walls and intercooling. Intercooling is a process that removes a portion of the heat of compression while air is piped from one stage of compression to another. An intercooler is a pipe in a multistage air compressor that connects the outlet port of a large cylinder with the inlet port of a small cylinder. See Figure A tube-and-shell heat exchanger is a type of intercooler that commonly use water to cool compressed air in industrial compressors.

10. A moisture separator separates moisture from compressed air by forcing it to flow against baffles.
A moisture separator installed at the discharge port of an aftercooler can remove the largest amount of moisture from the compressed air. A moisture separator is a pneumatic device that separates moisture from compressed air by forcing it to flow against baffles. See Figure 12-9.

11. Compressed air in a pneumatic system is dried by either refrigeration or desiccants.
An air dryer is a pneumatic device that dries compressed air through cooling, condensing, or absorbing. Air dryers use either refrigerated air or a desiccant material. See Figure Dry air is air free of water and oil vapor. Water and oil vapor is not always visible, most water vapor droplets are 0.5 μm to 2 μm in size, and the smallest droplets are visible at about 15 μm. Air dryers are used to dry air for sensitive equipment in instrumentation, medical applications, or food processing.

12. FRLs must be installed as close as possible to the point of work to maximize pressure control and provide proper lubrication for components.
A filter-regulator-lubricator (FRL) is a pneumatic device that is used to filter, regulate, and lubricate compressed air before it reaches the point of work. See Figure The filters used with most FRLs are similar to inline filters. While the regulator lowers the pressure going to the pneumatic system, the lubricator injects lubricant into the airflow. FRLs must be installed as close as possible to the point of work to maximize pressure control and provide proper lubrication for components.

13. A regulator is a pressure-reducing valve used to control downstream pressure.
A regulator is a normally open pressure valve that is used to control downstream pressure. A regulator includes an inlet port, an outlet port, a main biasing spring, a small biasing spring, a poppet, a diaphragm or piston, a pilot port, and an adjustment screw or knob. Regulators can have a diaphragm or piston design. See Figure A regulator operates in the following manner:
1. Compressed air from the piping enters the inlet of the regulator. Compressed air then flows through the outlet and pilot ports.
…Complete procedural list on page 389.

14. A lubricator is used to provide lubrication to component parts that move in a pneumatic system.
A lubricator is a device that injects a lubricant into the airflow. A lubricator is used to provide lubrication to component parts that move in a pneumatic system. The injected lubricant prevents the premature deterioration of seals and decreases friction between moving parts. A lubricator consists of an inlet port, an oil adjustment screw, a drip tube (on certain designs), a fill port, an outlet port, a mist generator, an oil filter, an oil reservoir, a manual drain, a metal bowl guard, a feeder tube, and an orifice. Lubricator designs can be mist or drip-feed. See Figure

15. An air filter-regulator filters and regulates airflow through prelu- bricated components.
Certain pneumatic components are available prelubricated. The advantages of prelubricated pneumatic components are that they reduce the use of oil and eliminate the hazard of it entering the breathable air in the facility. Breathable air contaminated with oil can cause health hazards. When a lubricator is not required, an air filter-regulator is used. An air filter-regulator is a pneumatic device that filters and regulates airflow through prelubricated components. With the exception that it does not use a lubricator, an air filter-regulator is designed and operated similar to a FRL. See Figure

16. When preparing compressed air for use in a pneumatic system, the correct type and sequence of filtering components must be used.
After compression, air must be properly prepared to efficiently accomplish work without damaging the pneumatic system or contaminating the environment where the system is installed. To prepare compressed air and remove contaminants, components must be installed in the proper sequence. See Figure Compressed air is prepared through the following procedure:
1. Atmospheric air is pushed into the air compressor. Before it reaches the air compressor, the air flows through an intake filter to remove the greatest amount of atmospheric contaminants as possible. In some systems, the air is run through a separator before it gets to the air compressor.
…Complete procedural list on page 392.