Pneumatic System Contaminants

• A contaminant is any unwanted substance that reduces air quality, damages equipment, or affects the performance of pneumatic systems, such as dirt, rust, oil, moisture, or microorganisms.

Main Contaminants

• Dirt consists of dust, pollen, and other airborne particles from the intake air
• Rust (iron oxide) forms when moisture reacts with metal pipes
• Dirt and rust can cause wear and tear on valves, seals, and other components, leading to reduced efficiency and equipment failure.
• Tiny liquid droplets or fine particles of oil come from lubricated compressors
• Oil mist and aerosols clog filters, reduce airflow, contaminate products, and degrade pneumatic components.
• Water vapor is naturally present in intake air and condenses as the air is compressed and cooled.
• Moisture causes corrosion inside pipes, freezes in cold conditions, and promotes bacterial or fungal growth.
• Bacteria, fungi, mold, and other microorganisms thrive in moist environments
• Microorganisms contaminate food, pharmaceuticals, and sensitive products, leading to hygiene and safety concerns.

Moisture in Compressed Air

• Atmospheric air contains water vapor, which gets compressed and concentrated.
• Cooling after compression causes condensation
• Higher relative humidity results in more moisture intake
• Warm air holds more moisture, and cooling causes condensation
• Seasonal humidity and temperature shifts impact moisture levels
• Excess moisture causes corrosion to pipes, valves, and tanks
• Water buildup can freeze, obstructing airflow
• Excess moisture causes pressure drops and shortens equipment lifespan.

Humidity and Dew Point

• Absolute Humidity is the total water content in air, measured in grams per cubic meter (g/m³).
• Saturation Quantity is the maximum amount of moisture air can hold at a given temperature and is higher in warm air.
• Relative Humidity (RH) is the ratio of absolute humidity to saturation quantity, expressed as a percentage (%).
• Higher RH indicates more moisture in the air.
• Relative Humidity (RH) = (Absolute Humidity / Saturation Quantity) x 100

Dew Point

• Dew point indicates when water vapor condenses into liquid, affecting system performance
• A typical range is 50°F to 94°F (10°C to 34°C).
• Lower dew points are needed for dry air applications
• Low dew point means drier air, which reduces corrosion and ice blockages, and improves efficiency
• A dew point curve is a graph that shows the relationship between temperature and moisture content in the air
• The curve indicates the temperature at which air becomes saturated and water vapor begins to condense into liquid.

Moisture Removal Methods

• Removing moisture prevents corrosion, contamination, and efficiency loss in pneumatic systems.
• These methods also ensure consistent performance and longevity of equipment
• Three primary drying methods are: absorption, adsorption, and low-temperature drying

Absorption Drying

• Absorption drying is a chemical process
• A drying agent reacts with moisture in compressed air, removing water vapor by forming a new compound

How Absorption Drying Works

• Air flows through a drying agent, such as lithium chloride or calcium chloride
• The drying agent chemically absorbs moisture, creating a new compound
• Water vapor is removed, but the drying agent gradually dissolves
• The drying agent has to be periodically replaced, typically every 2-4 times per year

Features of the Absorption Process

• It easily integrates into existing compressed air systems
• Reduces mechanical wear, improving reliability
• Operates via chemical reactions thus minimizing energy costs
• Requires only periodic desiccant replacement, reducing upkeep
• Provides consistent drying performance in various industrial applications

Adsorption Drying

• Adsorption is a physical process where moisture adheres to a solid surface without a chemical reaction
• Desiccant Drying or Regenerative Drying is another name for the same process
• Uses drying agents like silica gel or activated alumina that trap water molecules in their porous structure

How Adsorption Drying Works

• Compressed air passes through a bed of adsorbent material
• The drying medium, like silica gel or activated alumina, adsorbs water vapor, preventing condensation
• Once saturated, the drying agent must be dried (regenerated) using warm air or electric heating
• Systems often have two drying towers, with one in operation while the other regenerates

Low-Temperature Drying Process

• Low-temperature drying removes moisture from compressed air by cooling it to a point where water vapor condenses into liquid
• This method reduces the air’s dew point, causing moisture to separate
• This process is commonly used in refrigeration dryers
• A heat exchanger transfers heat efficiently, aiding in the extraction of condensed water

Stages of Low-Temperature Drying

• In the initial (pre-cooling) stage, hot compressed air passes through an air-to-air heat exchanger
• Air is precooled by outgoing dry air, reducing the refrigeration system's energy demand
• In the deep cooling (primary cooling) stage, pre-cooled air enters an evaporator, where it is further cooled to ~1.7°C (35°F)
• Cooling condenses moisture into liquid droplets
• Moisture Separation & Drainage: A moisture separator captures condensed water that is then discharged through an automatic drain trap
• Filtration (Final Purification): A fine filter removes remaining contaminants, such as oil aerosols and particles, ensuring clean air
• Air Reheating (Prevents Condensation in Pipes): The dried air passes back through the air-to-air heat exchanger.
• Air is reheated slightly to prevent pipe sweating and improve efficiency by increasing the effective air volume.

Compressed Air Filter with Pressure Regulator

• A device that removes contaminants, such as dust, oil, water, and particulates
• Ensures that the air used in industrial applications, pneumatic tools, and other systems is clean and free from impurities that could damage equipment or reduce efficiency

Parts and Functions

• Filter Bowl: Collects contaminants, including liquid particles and large dirt particles that are centrifuged out of the air.
• It also holds the condensate before it is drained
• Baffle Plate with Guide Slots: Directs the incoming compressed air into a swirling motion, which helps separate heavier contaminants like water and large dirt particles
• Drain Screw: Manually removes collected condensate from the filter bowl, though an automatic water separator can be used instead
• Sintered Filter (40 μm Mesh): Provides additional filtration by removing smaller dirt particles from the compressed air before it moves to the pressure regulator

How it Works

• Air enters the filter bowl and flows through guide slots in the baffle plate causing the compressed air to rotate
• Liquid and large dirt particles are centrifuged and collected
• Sintered filter removes finer dirt particles, which requires periodic cleaning or replacement
• Clean air flows through the pressure regulator to the lubricator and connected equipment
• Collected condensate is drained via the drain screw
• It is recommended to use an automatic water separator for high moisture levels

Automatic Water Separator

• An automatic water separator component removes liquid water from compressed air.
• It operates using a float chamber mechanism
• Water collects in a reservoir, and when it reaches a certain level, the float automatically triggers a drain to discharge the water
• Without an automatic water separator, a compressed air filter alone may not effectively remove liquid water, allowing moisture to remain in the system

Parts and Functions

• Connection Tube: Condensate from the filter flows into the float chamber
• Float: Moves based on the condensate level, which controls the drain operation
• Float Chamber: Collects condensate before it is drained
• Drain Valve: Opens to discharge the condensate when activated by the diaphragm
• Nozzle for Air Escape: Excess air to escapes when the drain cycle is completed
• Diaphragm: Moves due to compressed air pressure and controls the drain valve opening
• Drain Port: Exit for discharged condensate
• Manual Drain Pin: Manually drain when pressed
• Compressed Air Port: Guides compressed air into the chamber to press the diaphragm
• Nozzle: Opens when the float reaches height, allowing compressed air to activate the diaphragm and open the drain valve

How It Works

• Water removed by the filter enters the float chamber via the connection tube
• As the condensate level rises, the float is lifted
• When the float reaches a specific height, it opens a nozzle via a lever
• Compressed air flows through a port, pressing the diaphragm against the drain valve; then the drain valve opens, allowing condensate to exit
• The float closes the nozzle when the condensate level drops
• Remaining air escapes through another nozzle
• The separator can also be manually drained by pressing drain pin

Compressed Air Microfilter

• A high-efficiency filtration device that removes extremely fine contaminants
• Designed to remove extremely fine contaminants from compressed air
• Ensures clean and dry air for sensitive applications such as:
• Food processing
• Chemical pharmaceutical industries
• Process Technology
• Low pressure systems
• Removes 99.999% of water and oil particles
• Filters particles as small as 0.01 micron, ensuring high air purity

Parts and Functions

• Inlet Port is the entry point with compressed air
• Filter Cartridge (Borosilicate Glass Fiber) is the core filtration element that removes dirt particles as small as 0.01 microns
• Air flows from the inside to the outside of this cartridge
• Filter Bowl is the lower section that collects drained contaminants
• Drain Screw removes accumulated contaminants
• Outlet Port is the clean exit point

How it Works

• Compressed air enters through the inlet
• Air flows inside to outside with the borosilicate glass fiber filter cartridge
• The fine mesh traps dirt, water, and oil particles as small as 0.01 microns
• The filtered, clean compressed air exits through outlet and moves to connected equipment
• The trapped contaminants collect in the filter bowl
• Drain via the drain screw to prevent clogging
• Monitoring flow rate is essential

Pressure Regulator

• Adjusts system's air pressure to limit downstream pressure and protect downstream components

Main Components

• Inlet (High-Pressure Side): Where the fluid enters from a high-pressure source
• Valve & Diaphragm Mechanism: Adjusts the flow rate to maintain the desired pressure
• Spring & Adjusting Screw: Sets the required pressure level
• Outlet (Low-Pressure Side): Regulated lower-pressure fluid exits

Types

• Relieving Pressure Regulator
• Non-Relieving Pressure Regulator

Relieving Pressure Regulator

• Designed to maintain a consistent downstream pressure by adjusting the flow of gas from a high-pressure source.
• It has a vent hole, which allows the regulator to "breathe"
• Also includes an adjusting knob, regulating spring, flexible diaphragm, valve pin, valve, and valve spring

Non-Relieving Pressure Regulator

• Restricts airflow once it exceeds the set point
• It has no vent path, which traps the gas in the system
• Includes a set screw, spring, diaphragm, and valve plug

Applications of Pressure Regulators

• Pneumatic Systems, such as air compressors in workshops and gas stations
• Gas Distribution Systems such as LPG tanks and household gas meters
• Breathing Apparatus, such as scuba diving gear and hospital oxygen tanks
• Fuel Systems, such as car engines and motorcycles
• Hydraulic Systems, such as car brakes and elevators
• Refrigeration Systems, such as air conditioners and refrigerators
• Hazardous Gas Environments such as firefighting equipment and industrial plants

Compressed Air Lubricator

• A device that introduces a controlled amount of oil into a compressed air system to lubricate pneumatic tools and equipment
• Lubrication reduces friction, minimizes wear, and extends the lifespan of the equipment

Venturi Principle

• Pressure difference between the pressure in front of the air nozzle and the pressure at the smallest section of it suctions liquid from the container and is mixed with the air

Air Service Unit

• A critical component in pneumatic systems that is designed to condition compressed air
• Used in industrial machines and processes
• Composed of an FRL (Filter, Regulator, Lubricator) unit
• Air Filter removes solid particles, water, and oil from compressed air
• Pressure Regulator maintains a constant output level in a pneumatic system
• The Lubricator adds a controlled amount of oil mist in a pneumatic system

Importance of Air Service Units

• Improved equipment lifespan
• Energy efficiency
• Enhanced system performance
• Reduced downtime

Applications of Air Service Units

• Manufacturing and Automation such as controlling actuators, conveyors, and machinery
• Automative