Garage Articles

Air Preparation

Level 1 – General Shop Air
Level 2 – Oil and Residue Free Air
Level 3 – Dry Air
Filter Installation & Use
Regulator Installation & Use

Every tool requires some type of air preparation. At a minimum, air must be filtered and regulated. Some tools also require regular lubrication while others need completely dry air.

Every air system should include a general purpose filter and a pressure regulator. Depending on which tools you have and what you are working on, several other air preparation items may also be necessary. To determine what system components you need you must first select which level of air you need for your applications.

Level 1 – General Shop Air

Applications: Air tools, metal, and automotive work.

Description: This basic set-up helps protect you and your tools. The general purpose filter removes most solid and liquid contaminants down to 5 microns in size. This may include dirt, dust, pipe scale, rust, liquid water and bulk oil. A lubricator can also be used to automatically lubricate your air tools.

Required Components: General purpose filter and pressure regulator.

Optional Components: Lubricator.

Level 2 – Oil and Residue Free Air

Applications: Woodworking, cleaning, inflation

Description: An oil removal or coalescing filter removes particles down to .01 microns, which includes virtually all oil aerosols. Removing the oil and fine dust from the air protects your work surfaces. Oil residue left on wood can stain and discolor your finish while any oil blown into an object during inflation becomes trapped inside.

Note: An oil removal filter should always be placed after a general purpose filter. Otherwise, the coalescing element could be damaged or need frequent replacement.

Required Components: General purpose filter, oil removal filter and pressure regulator.

Level 3 – Dry Air

Applications: Sandblasting, paint spraying, powder coating, finishing applications.

Description: As compressed air leaves a tool, it cools down rapidly. This causes any water vapor in the air stream to condense back into liquid water. As a result, water vapor that safely passed through the filter and tool can now end up as water droplets on your work piece. This could cause blemishes in a finish or clog a sandblaster. To prevent this, the water vapor must be removed from the air stream by either condensing it into liquid and then filtering it out (refrigerated dryer) or absorbing it with a desiccant (desiccant dryer).

Required Components: General purpose filter, oil removal filter, desiccant dryer, pressure regulator.

Optional Components: Refrigerated dryer. There are two types of preparation equipment installations, conventional in-line installation and modular installation. Conventional installation is achieved by installing the product directly into the air line using threaded connections. The modular system uses a clamp to connect two units together. The modular system allows easy installation of the units without the cumbersome disassembly of the pipe system.

Common Particle Sizes:

Human Hair: 40-300 microns
Fine Sand: 10-50 microns
Dust: 1-150 microns
Liquid Water: 2-150 microns
Oil Vapor: 0.01-0.9 microns

As air enters the compressor, it carries with it dirt, water vapor, and other impurities. The compressor and distribution network can introduce oil, rust, and scale. These contaminants can decrease flow capacity through the build-up of sludge and rust in the main and branch lines and if allowed to enter the tool can cause accelerated tool wear, poor tool performance and application problems.

Selection of the proper type of filter depends on the application and the level of filtration need. In general to remove solid particles and bulk liquids you need a general purpose filter. To remove oil vapors you need a general purpose filter followed by an oil removal filter. To remove water vapor you need a general purpose filter followed by an oil removal filter and then a desiccant dryer or refrigerated dryer.

Once you know which type of filter(s) you need, keep the following in mind when selecting filters that match your application:

Air Flow: The larger the filter, the less it restricts the air flow. Make sure that the filter you select exceeds both the SCFM of the compressor and tool.

Bowl Construction: A clear polycarbonate bowl is generally used since it is very tough and easy to use. However; polycarbonate should not be used if the bowl will be exposed to any of the following: air pressures greater than 150 PSI, direct sunlight, chlorinated hydrocarbons, ketones, esters, and certain alcohols. In these conditions, choose a filter with a metal bowl.

Bowl Capacity: A larger bowl will require draining less frequently. This is especially important in very humid environments or if it is installed in a difficult to access location.

Filter Installation & Use

Installation:

Install as far away from compressor as possible. This allows air to cool and moisture to condense. It is easier to remove condensed moisture than in its vapor state.
Install as close to the tools as possible.
Install before regulators and lubricators.
Install filters vertically with bowl on bottom.
Install with arrows pointing in direct of air flow (towards tool).
Seal threads with PTFE thread sealant.

Use:

Drain frequently. If liquid reaches the element, the filter will not function properly.
Clean or replace filter elements regularly 9 at least once per month if used frequently).
Bowls and general purpose filter elements can be cleaned with soap and water solution.
Coalescing filters cannot be cleaned. Most coalescing filters come with a service indicator. Replace the filter element as needed.
Always depressurize system when removing bowl
Desiccant can be recharged by baking in oven.

Pneumatic devices are designed to work at a certain pressure. The best operation and life is obtained by using the pressure recommended by the tool manufacturer. A regulator is used to reduce and maintain the pressure a level required by the device. Regulator will also help to maintain a near constant outlet pressure despite changes in inlet pressure. This is important for two reasons. First, tools have a maximum pressure limit. If exceed the tool could fail or personal injury can result. Second, higher pressures can increase tool and air compressor wear.