I have this Craftsman.
 SCFM Delivery At 40 psi 5.6 SCFM
SCFM Delivery At 90 psi 5.1 SCFM Got a great deal on a floor model ($330) This little chart that sears uses to "rate" the compressors usability, so take it for what its worth. This model is a 7, and I haven't used anything it can't run, not yet anyway. Long story short, I am very very happy with this one. 
The following is the ABC's of air compressors according to sears:
ABCs of Air Compressors Advantages of Air "Pneumatic" tools, or tools fueled by air power, offer several advantages over their electric counterparts. For starters, pneumatic tools are often safer (no risk of fire hazard or electric shock) than electric tools - not to mention less expensive. Pneumatic tools are generally lighter (resulting in less fatigue) and smaller in size, yet they are often more powerful than electric power tools. In addition, pneumatic tools usually outlast electric tools since they run cooler and aren't exposed to harmful stalling or overload. Pneumatic tools, however, are not self-reliant. They require the assistance of an air compressor. Air compressors provide pneumatic tools with the air power necessary to get the job done - quickly and efficiently. About Air Compressors You are now aware that air compressors can be used to power pneumatic tools. You may also know that you can use an air compressor to pump up a deflated bicycle or automobile tire. But that's not all! Air compressors actually have a variety of uses that transcend powering pneumatic drills and inflating tired tires. In fact, you can utilize air compressors to: * Power pneumatic tools, such as ratchets, screwdrivers, drills and nail guns
* Inflate tires, rafts, mattresses and balls
* Paint automobiles, bicycles, furniture and fences
* Clean air filters, lawn equipment and work benches
* Nail or staple cabinets, frames and shingles
* Spray fertilizer and fence wash
* Sand autobody and woodwork projects
* Remove rusty bolts and hardware
* Cut sheet metal An air compressor is a "must have" tool for every workshop. Read on to learn how to select the best compressor for your needs. Primary Considerations Before you embark on your search for a new air compressor, please take a moment to review the fundamental criteria that define the capabilities of an air compressor. SCFM - SCFM stands for standard cubic-feet-per-minute. SCFM is, perhaps, the most essential item for selecting an air compressor. SCFM represents the volume of air that a compressor can output, and is usually defined for a specific PSI (see below). For example, a pneumatic impact wrench may require 4 SCFM at 90 PSI. So you need to select a compressor that can meet this requirement. If you intend to run more than one tool at a time - two impact wrenches for example, - than you need a compressor that is capable of 8 SCFM. It's a good idea to select a compressor that can provide 50% greater SCFM than your tools require as a margin for error. You may see CFM rather than SCFM in some literature. SCFM is a more technical and specific description of air volume than CFM. SCFM is used to indicate that the CFM measurement was calculated at 60° Fahrenheit, with 0% relative humidity and an ambient air pressure of 14.7 pounds per square inch. SCFM is used to "standardize" the measuring of CFM so all compressors are evaluated in identical environments. In other words, this assures an "apples to apples" comparison of CFM. PSI - PSI stands for pounds per square inch. Each air compressor has a PSI rating, which reflects the maximum amount of air pressure (power) that the compressor can deliver. Most compressors can achieve a maximum air pressure between 125 and 175 PSI. Most mechanics' air tools require at least 90 PSI to run. The difference between the maximum pressure and 90 PSI is the "usable" air available to run the tool. More usable air means the compressor will run less frequently and the air tool will have more than adequate air pressure for a longer period of time. A compressor with a maximum pressure of 150 PSI has 60 PSI (150 - 90) of usable air. Compressors with higher PSI ratings offer two benefits: (1) greater air storage than those with lower PSI ratings since more air can be squeezed into the storage tank, and (2) more available power since the air is at a higher pressure. So be sure to select an air compressor with enough PSI to match your needs. Horsepower - An air compressor's horsepower (HP) rating reflects how much horsepower its motor produces. Generally, compressor motors range from 2 to 7 HP. Higher horsepower motors tend to yield greater PSI and SCFM and can accommodate heavier workloads. Tank Size - Air compressor tanks are measured in gallons. Larger tanks hold more compressed air, so the compressor motor or engine does not have to run as frequently. Duty Cycle - The duty cycle is a rating representing, on average, how long the motor is designed to run. For example, a compressor with a 50% duty cycle is designed to run 50% of the time or 30 minutes of each hour. If you are running an orbital sander eight hours per day, and the sander requires 4 SCFM at 90 PSI, and your compression puts out 4 SCFM at 90 PSI, it will be running 100% of the time, and may exceed the duty cycle. On the other hand, if you only run the sander for one hour a day, the compressor may run hard for one hour, but not at all for the remainder of the day. In this case, the 50% duty cycle may be more than adequate. Other Considerations Aside from SCFM, PSI and Horsepower ratings, there are several additional factors to consider when determining which type of air compressor best suits your individual needs. How do you plan to use your new air compressor - presently and in the future? Does your air compressor need to be portable, or will a stationary compressor suffice? What power supply will be readily available? Which convenience features appeal to you? Compressor Styles Compressors can be categorized by how they store the compressed air. Below are definitions of the two basic storage styles. * Storage Tank Compressors - utilize tanks to store compressed air. When the pressure inside the unit's storage tank reaches the compressor's maximum PSI, the motor automatically shuts off. As the air in the tank is depleted by using an air tool, the diminished air supply causes the pressure level inside the tank to decline. This drop in pressure, in turn, pushes the motor to restart. The active motor then begins to rebuild the pressure inside the tank. The operator can adjust the pressure settings to meet his or her specifications. * Compact Air Compressors - do not utilize storage tanks. They are the smallest, lightest compressors on the market and must continuously run to an air supply. These compressors are most often used to inflate tires and sports equipment as well as power glue guns, caulk guns and small spray guns. Compressors can also be defined by the method they use to compress air as defined below: * Single-Stage Compressors
- contain a single piston that compresses air and delivers it to the unit's storage tank. To compress air, the piston moves up and down in the cylinder. On the downstroke, air is drawn in through the air intake valves. The exhaust valve remains closed. On the upstroke of the piston, air is compressed. The intake valves close and compressed air is forced out through the exhaust valve, through the outlet tube, through the check valve and into the air tank. Working air is not available until the compressor has raised the air tank pressure above that required at the air outlet. Light-duty compressors (with maximum PSI ratings below 150) usually feature single-stage systems. This type of air compressor is suitable for most at-home users. * Two Stage Compressors - contain two pistons that compress and deliver air to the unit's storage tank. The compression process is two-fold. First, air is first compressed to an intermediate pressure in the large bore cylinder, and after passing through an inter-cooler, the air is further compressed to a higher pressure in the smaller bore cylinder. This process continues until the air tank pressure reaches the factory set cutoff pressure. At that point the pressure switch shuts the electric motor off. a single piston compresses the air and delivers it to the second piston via a check valve. After the air is pushed through the check valve into the second piston, it is compressed even further and, finally, delivered to the compressor's storage tank. Heavy-duty compressors (with maximum PSI ratings above 150) usually feature the two-stage system. Two-stage compressors are best for shop or industrial/professional environments. Maintenance Considerations You will have to perform routine intake air filter and tank maintenance on all compressor types. You can, however, eliminate further maintenance by choosing an oil-free compressor. * Oil-Free Compressors pack plenty of power for a majority of noncommercial uses. They contain sealed bearings and generally require less maintenance than their oil-lubricated counterparts. Since these compressors don't require lubrication, you won't have to hassle with messy oil spills and output air is cleaner. * Oil-Lubricated Compressors require regular oil changes, but are better under heavy use as the oil helps dissipate heat build-up. Specific intervals vary among models, so be sure to check your owner's manual. The majority of industrial compressors are oil-lubricated. Etc. Air compressors can be powered by either gas or electricity. Electric-powered compressors are more common than their gas counterparts and are simple to use in areas with abundant electricity. Electric compressors run on either 120-volt or 240-volt systems. Most portable compressors run on 120 volts while stationary compressors usually require 240 volts. A 240-volt system requires an electrician to assist with the installation. Gas-powered compressors are popular in areas with limited electricity, and should always be used in open, ventilated locations. Air compressors are available in a variety of layouts - horizontal, pancake and vertical, being the most popular. Be sure to choose a compressor with a layout that best suits your individual requirements. For instance, if you plan to store your compressor beneath a workbench, you will probably select a horizontal compressor.
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