Air Compressor Buying Guide for power tools and tire inflation

Air Compressor to power impact wrench for big lorries lug nuts and tire inflation.

Performance rating

• Smaller tools require between 0-5 SCFM (Standard cubic feet per minute) -- braid nailers, reversible drills, and impact wrenches required 0 to 5 CFM at 70 to 90 PSI
• Larger tools can require 10 or more SCFM -- larger shear and sanders require at least 10 ore more CFM at 100 to 120 PSI
• Air tank capacity = at least 60 to 120 gallons
• Horse Power = 5.5 or 7.5
• Two stage air compressors provide more reliable air source in commercial, and industrial and automotive applications.
• Multistage units tend to be more efficient, compressing air to a higher pressure than single-stage compressors. This allows more air to be stored for future use while generating less heat, reducing wear and extending compressor life
• Belt driven compressors generally have a longer life with less vibration and heat transferring from the motor/engine to the pump.
• Cast iron cylinder or cast iron pump sleeves - cast iron is typically standard material for cylinders
• Oil Free (Oil-less) - compressors are virtually maintenance free performers for light to general duty applications. No need for periodic oil changes.
• V-design cylinders — V-design cylinders typically run cooler that in-line cylinders. Heat is a compressors worst enemy.
• 100% Continuous Speed operation vs. Auto Start/Stop operation — Auto start/stop operation has preset cut in/cut out pressures. The compressor actually stops and turns back on as air is needed. With constant speed operation, the compressor runs 100% of the time and simply adjusts the air output. Dual control compressors offer both auto start/stop and continuous speed operation.
• Gas-powered air compressors are ideal for job site pneumatic applications where electrical power is not available. Northern offers compressors driven by reliable Honda or Kohler engines.
• Cast iron, belt driven, oil lubricated compressor are far superior in durability. For spraying paint you'll just need to add a drier to the output. Oil filled compressors are the best type to have and use. The oil-free are for occasional tire filling, blowing dust off your work, or maybe spraying some weed killer on yer garden. but, for trouble free use, the type with the cast iron or aluminum block, which has to have the oil changed occasionally, and checked frequently, is better in the long run. Better for impact guns, air sanders, air grinders, anything for which you will need the punch of lots of supplied air. 2 cylinder is best.
• Tools that require constant power such as grinders and sanders will require more CFM than tools which need sporadic power such as nail guns

• FAD = Free Air Delivery (is the actual quantity compressed air converted back to the inlet conditions of the compressor). FAD = Measured in CFM for imperial and L/min in SI (Example 485 L/min = 17.13 CFM)
• Air Tank Capacity = Measure in Liters or Galon (For example 250 Liters = 66 gallons)
• Pressure = Measure in Bar or PSI (For example 12 bar = 174 Psi)
• Motor = Measured in KW/P (For example 5.5 HP or 7.5 HP)
• Rated Pressure = Measured in Mpa/psi (For example 1.25 Mpa/180 Psi equivalent to 12 Bar/180 psi)

Questions:

1. How to determine/set the torque measure using impact wrench to screw back lug nut?
2. Buy by Horse Power or CFM? The answer = CFM -- although more horse power produce more CFM

Reference Conversion Tools

1. Convert kW to HP
2. Convert L/Min to CFM (Cubic feet per minute)
3. Convert Liter to Galon
4. Convert BAR, mPA to PSI