Compressor Size Guide
The first questions to ask yourself are:
- What electricity supply is available at your premises? (single or three phase)
- Do you currently have a compressor?
- If so, what size compressor is it? Does it cope ok with the current demand on it?
- What are the future plans? More staff and tools?
Electrical Supply
Single Phase (Domestic) 230 Volts
Standard 13 Amp plug
Note: Do not use long extension cables when running the compressor! Better to use a long air hose.
Here are all the compressors available that run off a 13 Amp plug:
Workshop range:
/air-compressors/garage-diy-air-compressors.html
Semi Pro range
/air-compressors/workshop-semi-professional-air-compressors.html
The biggest compressor you can get that runs off a 13 Amp plug is the ABAC A29B 150 FM3
/abac-a29b-150-fm3-belt-driven-air-compressor-3-hp-150-litre-11-2-cfm-single-or-three-phase.html
And this is the largest portable one:
/abac-pro-a29b-90-cm3-b312-100-belt-drive-air-compressor-3hp-90-litre-14-cfm.html
Single phase (Professional) 230 Volts
Any single phase compressor bigger than 3hp on a 150 litre air receiver will require a minimum of 20 Amps supply, with type D breakers. This is because of the draw on the starter motor.
These are all the single phase 20 amp compressors available:
/air-compressors/professional-industrial-compressors.html
The biggest compressor you can get is the ABAC A29B 150 FM3
Main Benefit of Single Phase
• Excellent second-hand resale value
Three phase (Professional) 400 Volts
See them all here.
/air-compressors/professional-industrial-compressors.html
Main Benefit of Three Phase
• Approx 2/3 cost saving over single phase
• Stable supply
• Longer motor life
Single vs Three phase
Three-phase compressors are more efficient producers of compressed air than single-phase equivalent units, so where a three-phase supply is available the best option is the three-phase compressor.
110 Volts
For on site / portable use.
There are limited compressors available running off 110 Volts.
See them all here:
/air-compressors/110-volt-air-compressors.html
Air Tools CFM Table
Bodyshop
Using the air tools CFM table, add all the tools CFM together and divide by two. The result figure is the minimum free air you require.
Workshop
Using the air tools CFM table, add all the tools CFM together and divide by three. The result figure is the minimum free air you require.
Quick guide to CFM/FAD output (approx) of existing compressor
Multiply motor hp by 3.3 = output in CFM / FAD
Multiply motor kW by 4.5 = output in CFM / FAD
Multiply motor kW by 2.1 = output in L/sec / FAD
Using the table
If its tools, please tick the tool with the highest continuous use CFM requirement. So if you are planning on use say an 3/8” impact wrench, a ¼” drill and sometimes a belt sander, then pick the sander as your highest CFM tool at 27 CFM
Air Tool CFM Table
Tool Type |
Continuous use CFM used (approx.) |
50% CFM Average Use (30 Seconds) |
25% CFM Average Use (15 Seconds) |
¼” Drill |
15 |
7.5 |
3.75 |
5/16” Drill |
18 |
9 |
4.5 |
3/8” Drill |
18 |
9 |
4.5 |
½” Drill |
20 |
10 |
5 |
¼” Ratchet |
14 |
7 |
3.5 |
3/8” Ratchet |
18 |
9 |
4.5 |
½” Ratchet |
18 |
9 |
4.5 |
3/8” Impact Wrench |
12 |
6 |
3 |
½” Impact Wrench |
21 |
10.5 |
5.25 |
¾” Impact Wrench |
38 |
19 |
9.5 |
1” Impact Wrench |
70 |
35 |
17.5 |
¼” Impact Wrench |
15 |
7.5 |
3.75 |
5/16” Impact Wrench |
16 |
8 |
4 |
Flat Bed Orbital Sander |
20 |
10 |
5 |
5” Random Orbital (DA) Sander |
15 |
7.5 |
3.75 |
6” Random Orbital (DA) Sander |
22 |
11 |
5.5 |
5” High Speed Sander |
23 |
11.5 |
5.75 |
7” Angle Sander |
23 |
11.5 |
5.75 |
Belt Sander |
27 |
13.5 |
6.75 |
3mm (1/8”) Die Grinder |
7 |
3.5 |
1.75 |
6mm (1/4”) Die Grinder |
17 |
8.5 |
4.25 |
4” Angle Grinder |
19 |
9.5 |
4.75 |
5” Angle Grinder |
38 |
19 |
9.5 |
7” Angle Grinder |
42 |
21 |
10.5 |
Straight Ling Polisher |
19 |
9.5 |
4.75 |
8” Angle Polisher |
27 |
13.5 |
6.75 |
Blowgun |
25 |
12.5 |
6.25 |
Fibreglass Saw |
19 |
9.5 |
4.75 |
Reciprocating Saw |
12 |
6 |
3 |
Chisel Gun |
12 |
6 |
3 |
Riverter |
7 |
3.5 |
1.75 |
Upholstery Tacker |
3 |
1.5 |
0.75 |
Coil Nailer |
7 |
3.5 |
1.75 |
Spray Gun Normal |
8 |
4 |
2 |
Spray Gun HVLP |
14 |
7 |
3.5 |
How many people will be using tools at one time?
If its just you using the tools.
Multiply the highest CFM by 1.2. This is to over compensate the CFM required.
If its 2 people, then multiply the CFM required by 1.7.
Note: Small average low use.
This is not continuous use. This is average interminant use.
If the CFM figure is bigger than 50 CFM then you will need a screw compressor. The highest direct drive compressor you can get is 20 CFM and the highest CFM from a belt driven is the twin at 34 CFM delivered.
If you are going to use the compressor for continuous use or any more than 2 people using tools at one time, then you need to be looking at screw compressors. Available with or without receivers, dryers and filters.
Disclaimer
Please note, this is only a guide and should not be treated as anything other than a guide.
Call us if you are not sure.
Definitions
Pressure
Pressure is the force of the compressed air.
Measured in PSI (Pounds per Square Inch) or Bar.
If the pressure is too low then this will cause the tools to not work. If the pressure is too high then this could put unnecessary wear on the tools.
Displacement (Volume)
This is the theoretical volume produced by the compressor
The measured by the swept volume of a cylinder multiplied by the number of compressions in a minute. Expressed in CFM (Cubic Feet per Minute).
The CFM (Displacement) should not be used in calculating the size of compressor you require. Because it is theoretical, it does not represent the actual CFM delivered after heat and friction losses in the compressor system.
Free Air Delivered
Remember displacement is the theory and CFM (Free Air Delivered) is the actual volume delivered.
For calculation purposes always use free air delivered figures.
Single Stage / Two Stage Compressors
Single Stage Compressors
One or more cylinders producing the final pressure in one compression.
Normal maximum pressure 150 psi. g.
Two Stage Compressors
Air is compressed in the first stage, cooled then compressed to final pressure in the second stage. Normal maximum pressure 200 psi. g.
Two stage provides more air for less energy.
2 Stage compressors start here: /abac-pro-5900b-200-ft5-5-b5924-200-belt-driven-air-compressor-5-5-hp-200-litre-23-cfm-three-phase.html
Compressed Air Hose Guide
¼” (6mm)
Upholstery tacking gun, Tyre inflator, Airburshung, Blow gun
5/16” (8mm)
Spray guns, 18 gauge pinner, brad nailer, 3/8” drill, ratchet wrench, small die grinders
3/8”
HVLP/LVLP Spray Guns /
½” impact wrench, sanders, 4” grinders,
1/2”
1” and 3/8” Impact Wrenches