Air Force

Ensuring a Smooth Finish

Specifying Air Compressors for Sandblasting Applications

By Angela Kelly

Sandblasting just sounds like a gnarly process. It’s the act of smoothing, shaping and cleaning a hard surface by forcing solid particles across an object at high speeds, like super sandpapering a façade to a flat finish. Using an air compressor and a sandblaster, professionals can do everything from refurbishing buildings to creating works of art.

But sandblasting is a serious application, so specifying air compressors for sandblasting applications requires some attention to the quality and condition of the compressed air. Atmospheric air entering a compressor always contains water vapor or humidity. The higher the humidity the more moisture is hanging in the air. At 75 degrees F and 75 percent relative humidity, for example, 20 gal of water will enter a typical 25-hp compressor during one day of operation.

When the air is compressed, this water content is concentrated, but because compression also heats the air, much water remains vaporized. As the compressed air exits the discharge and enters the sandblasting pot or hopper, the water vapor condenses into liquid droplets. This water will not only contaminate the blast medium, it will lead to build up and clogging in the tube and spray nozzle. Using an aftercooler will cool the air to about 15 degrees F above ambient and allows the water to be condensed and removed before it can cause “clumping” in the blast media.

Air compressors with built-in aftercoolers provide the most effective and convenient performance for blasting pros. Because there is no need to worry about sizing or external power sources, these all-in-one packages are completely mobile and much easier to transport. Other specification criteria for portable compressors used in sandblasting applications include:

1. Fully-enclosed and insulated canopy for reduced noise levels.

2. Solid steel flooring to prevent dust from reaching internal components and intake air.

3. Cold-start battery and anti-frost protection for better reliability in a variety of climates.

4. Large fuel tank for fewer fill-ups.

5. Towable units: Torsion bar suspension, tow bar with safety chain and instrument and lighting package for safe, easy towing between sites.

6. Truck-mounted: Forklift slots and single-point lifting bail for easy mounting on a truck bed with curb-side visible instrument panel.

In today’s economy, fuel efficiency is also especially important. Consider your air-per-gallon ratio. Some compressors are designed with larger airends turning at higher speeds, which allows them to offer more cubic feet per minute (cfm) in output per gallon of fuel expended in operation.

Angela Kelly is the communications director for Kaeser Compressors, based in Fredericksburg, Va.

Grade School

Learn the Difference Between Rental
Market and Contractor-Grade Compressors

By Russell Warner

All air compressors are not designed equally and they shouldn’t be. Air compressors are probably the most versatile piece of utility equipment on the market; however, it is important to match the right air compressor to the application. Basic construction-site applications require the use of many tools, and an air compressor is needed to operate them.

Generally, air compressors fall into two categories: compressors designed for the rental market and contractor-grade compressors.

Rental-grade compressors are designed to be cost-effective, compact and easy to operate. These units have fewer options and are focused on the most common applications. They are typically used in landscaping for tasks such as maintaining sprinkler systems or by general contractors for pavement breaking, pressure testing or operating general-purpose pneumatic tools.

Pressure and volume are the key identifiers in choosing the right air compressor for the job. Pressure is measured in pounds per square inch (psi) and volume in cubic feet per minute (cfm). You will generally find rental units fall within a range of 160 to 185 cfm at 100 to 125 psi. For general tool operation, the air compressor will need to be at least 100 psi, but the operator should consult the tool’s operator’s manual for required volume and pressure settings. Use of multiple tools at one time will require a higher-volume unit. For instance, a 160-cfm at 100-psi air compressor can operate up to two pavement breakers at one time, but more than two will require more volume.

Construction contractors usually look for more versatility in an air compressor. They often require increased internal storage, hose reels and custom gage packages on their machines. The most common needs for contractor-grade air compressors are for cleaning, blasting, painting, renovation, installation and demolition. For these varying applications, an air compressor will need to be more customizable and include more options than a rental unit.

The most commonly used air compressor in the construction industry is a 185-cfm at 100-psi unit. Depending on the application and number of tools running at a time, the volume and pressure may need to increase to 375 cfm at 125 psi. These units also tend to be much more durable for the rugged environment they are used in with heavy-duty enclosures and towbars.

A current trend in air compressor design for both categories of rental and industrial is the use of composite materials on unit enclosures and end-caps. Manufacturers are moving away from steel to eliminate corrosion and lessen the weight of the compressor. Another important trend is more streamlined and wind-resistant body designs for better gas mileage when towing.

Whether you obtain a cost-effective air compressor, or a larger unit for blasting, it is important to maintain the air compressor with a routine maintenance schedule. Your dealer should provide you with checklists to follow for daily, weekly and monthly maintenance.

Russell Warner is a product marketing manager for small air compressors at Doosan Infracore Portable Power, based in Statesville, N.C.

Air Care

Daily Preventive Maintenance Will Extend the Life of an Air Compressor

By Dan Leiss

He is the loyal companion who is always there by his owner’s side. The one who spends his whole life obeying every command. The companion is selfless, always supporting his owner’s needs. It’s a familiar story — that of a man and his trusty air compressor.

Okay, maybe this isn’t exactly what you were thinking, but in many ways an air compressor is just like a pet. When properly cared for, a compressor will provide years of quality, reliable service to its owner. And just like a pet, a compressor needs attention every day.

Even if you feel you lack the time or know-how to maintain an air compressor, rest assured that it is actually a relatively simple and quick process. All it takes is a couple of minutes before each use to perform a few easy checks and procedures and your compressor will work in top condition for years to come.

Before Each Use

While your pet may need a bath once in a while, it is always a good idea to keep an air compressor clean. It will be easier to detect leaks and broken or loose components on a clean machine.

Before turning on the machine, do a visual inspection. Check the hoses for kinks and the electrical wiring, tubing and piping for any damage. Also check the controls, gauges, accessories and instruments to make sure there are no loose mountings or visible damage. Check all connections and tighten any loose nuts and bolts.

The next step is to check the pump oil level. To do so, first disconnect the power source and place the compressor on a flat surface. Remove the oil fill plug and check the level, then insert a screwdriver into the crankcase. Inspect the oil on the screwdriver. If there are signs of contaminants, such as water or dirt, change the oil. Otherwise, change the oil annually. If a gas engine powers the compressor, check the engine oil level, as well, which also should be changed annually.

Fuel filters may be changed to accommodate an air compressor’s daily task. There are two types of filters: standard and coalescing. A standard filter will trap dust particles based upon micron size, while a coalescing filter will remove water and oil from the air. Provided the correct filter is used for each application, it should only need to be replaced monthly or every few months.

During and After

Now that the compressor is ready to start, listen for any unusual noises or vibrations that may signal a problem. Knocking or vibrating could indicate a worn connecting rod or piston pin, dirt on the piston or a loose flywheel or pulley. Chatter at the pressure switch or magnetic starter may indicate the switch needs to be adjusted or replaced. Listening and recognizing unusual noises are the best ways to identify potential concerns.

The final task that needs to be performed on the compressor every day is to drain water out of the tank. Depending on the humidity level, this may need to be done more than once a day. Humidity may cause moisture to form in the pump and produce sludge in the lubricant, which will cause premature wear on the parts. Remember to collect and dispose of the condensate properly, as it may contain oil.

While daily maintenance prolongs the life of a compressor, it does not end here. Basic weekly and monthly checks are important. Checking the safety relief valve, inspecting the drive belt tension and checking air connections and compressor joints for leaks are all critical to the longevity of the machine. Information on all maintenance procedures can be found in the owner’s manual.

Costly downtime, expensive repairs and the need to purchase a new machine can typically be avoided if proper attention is given to the air compressor. In fact, a compressor can last 10 to 15 years if cared for properly. Treat a compressor well and it will respond with years of loyal and reliable service. Best of all, it doesn’t need to be taken for long walks.

Dan Leiss is president of Jenny Compressors, based in Somerset, Pa.

Air Force

Five Brands of Compressors Offer the Ultimate in Air Power

By Keith Gribbins

Atlas Copco HardHat

Atlas Copco’s HardHat 185-cfm compressor has a polyethylene canopy. The canopy resists rusting, scratching, denting and extreme temperatures, thus eliminating external repair costs and downtime due to damage. The canopy protects the compressor from damage at the worksite, which helps reduce the cost of ownership and boost resale value. Plus, the controls, lights and couplers are all tucked away and recessed to minimize the chance of damage. A four-cylinder, 49-hp John Deere diesel engine and Atlas Copco’s patented rotary screw airend generates a guaranteed 185 cfm. RS#69

DeWALT Gas Compressors

DeWALT, a leading manufacturer of industrial power tools, announced the launch of its new heavy-duty, gas-wheeled portable compressors (D55672, D55684, D55690 and D55695) for residential construction applications. The innovative designs of these units provide professional contractors with increased durability, performance and versatility on residential jobsites. The new compressors are ideal for multiple applications, including framing, roofing, remodeling, deck building and trim carpentry. This launch highlights DeWALT’s commitment to the residential end-user by providing heavy-duty power tools to meet jobsite demands. RS#70

IMT Compressor /Welder /Generator

Iowa Mold Tooling Co. Inc. (IMT) continues to improve the way mechanics perform their jobs in the field with the introduction of the new IMT CAS35WG (compressed air system 35 cfm welder/generator). The CAS35WG is a compact, hydraulic compressor/welder/generator designed to increase productivity and decrease vehicle weight, and the unit is a perfect complement to the IMT Dominator mechanics truck. Combining the compressor, welder and generator into one unit provides a savings on service costs and reduces vehicle weight. The hydraulic unit is composed of a 35-cfm reciprocating air compressor, a 250-amp welder and a 5,000-watt generator. RS#71

Ingersoll Rand AirSource

Ingersoll Rand AirSource and AirSource Plus portable rotary-screw compressors combine the most valued features of the previous generation of compressors with the latest technologies. The corrosion-resistant compressors offer rental customers Ingersoll Rand quality and reliability, with enhanced performance and value. The Ingersoll Rand AirSource compressor, 160 cu ft per minute at 100 psi, runs off a high-performance 49-hp Ingersoll Rand diesel engine with an eight-hour runtime. The AirSource weighs only 1,850 lbs and allows for two-tool use, creating the best value in a 160-cu ft per minute compressor size. RS#72

Kaeser’s M57 Utility Mount Compressor

Kaeser’s versatile and user-friendly M57 Mobilair Utility Mount portable compressor delivers 210 cfm at 100 psi. Its intuitive design includes an easy-to-read curbside instrument panel protected by an aluminum hinged lockable door, as well as forklift slots and a single-point lifting bail to make cross mounting on service vehicles an easy task. Its large 28-gal fuel tank provides 10 hours of uninterrupted operation and its high-capacity, cold-start battery ensures reliable operation in severe working conditions. The heavy-duty, four-cylinder diesel engine combined with energy-saving Sigma Profile airend produces more air with less horsepower and complies with Tier 3 EPA emissions standards. RS#73