What Do I Need to Know When Buying an Air Compressor?

Why is Compressed Air Useful?

The compressed air energy contained within a balloon is equal to the energy required to inflate it. The energy is stored as pressure.

When the balloon bursts, the pressure equalizes and the energy is released. This energy can be used to complete work.

Two Types of Air Compressors:

1. Piston Compressors

Piston Compressors:


Single Phase 

How do they work?

 Just like an engine of a car, as the pistons rise, they press the air into a tighter space which creates pressure. Compressors can have 1 stage or 2 stages of compression.

Single-Stage Piston air

is compressed once and then discharged. Max Pressure = 130 PSI. Two-Stage Piston air is discharged once in a low pressure side and again in a higher pressure side before discharge. Max pressure = 175 PSI.

Advantages of Piston Compressors:

- Low Price
- Easy to Understand
- Simple to Maintain

Duty Cycle: Piston compressors generate a lot of heat during the compression process, they are restricted to the amount of time they can operate. This is what we can the "duty cycle". Single-stage pistons normally have a 50% duty cycle and two-stage pistons have a 75% duty cycle.

2. Rotary Screw Compressors

Rotary Screw Compressors:

 Variable Speed Compressors Quiet Rotary Screw Compressors

Rotary screw compressors act like superchargers in a sports car. Two helical rotors match each other and rotate together. As they do, air is squeezed into a smaller and smaller cavity, creating increasing pressure. A thin film of oil lubricates the rotors and keeps them from overheating.

Advantages of Rotary Screw Compressors OVER Piston: 

- Runs cooler so it can operate continuously - More stable pressure - Air always available when you need it - Low sound level- 7 times quieter than a Piston - Better work environment for your team - Lower Oil Carryover - Reduces product contamination - BEST choice for painting - Better for the environment

Sizing the Compressor

To size the compressor, we need some basic information.

1. Maximum Operating Pressure: - Look at the pressure ratings on the equipment - Are there any known pressure issues?

2. Total Air Requirements (Total cfm) - Add up all the cfm ratings on the equipment (they are listed on all tools) - Do you want to wait on the compressor for air? - How many tools are you using at once? - Have existing compressors and storage tanks?

Calculate the Correct Air Requirements 1. Determine the total air requirements (in cfm) for all equipment 2. Make adjustments: - Add 10% for leaks and growth in business - Use consumption x 1.5 for piston compressor - Use consumption x 1.0 for rotary screw 3. Determine final air requirement in cfm for the equipment 4. Check your air requirements with the "benchmarks" below on the number of workers

2.5HP 50L Oil-Free Dental Air Compressor Clean Air Class Zero Certified

2.5HP 50L Oil-Free Dental Air Compressor Clean Air Class Zero Certified

$3,700.00 NZD exc.
$4,255.00 NZD inc.


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1.5HP 25L Oil-Free Dental Air Compressor Clean Air Class Zero Certified

1.5HP 25L Oil-Free Dental Air Compressor Clean Air Class Zero Certified

$2,450.00 NZD exc.
$2,817.50 NZD inc.


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6.5HP 50L Cast Iron Petrol Air Compressor SF302 KOHLER

6.5HP 50L Cast Iron Petrol Air Compressor SF302 KOHLER

$1,950.00 NZD exc.
$2,242.50 NZD inc.


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Who we are and how Ash Air can help your business!

Ash Air has been around in New Zealand since 1979, and we’ve grown into a nationwide company with international support and a reputation for quality and reliability.We look after all things compressed air for your business!

  • Reciprocating, Screw, air compressors
  • Vacuum pumps
  • Nitrogen
  • An extensive line of air treatment components

Ash Air's range of Chicago Pneumatic, Alup, Pneumatech, and Quincy compressors are used extensively around the world in industries ranging from oil and gas to food, automotive and farming, and we bring you these world class compressors here in the land of the long white cloud.Our technicians are compressed air equipment experts and are dedicated to addressing customer needs. Supported by a 13 locations nationwide, Ash Air offers one of the widest selections of compressed air equipment and parts available today in New Zealand.

Reliability and Efficiency

With Ash Air compressors, you can count on reliability and high performance for even the most demanding applications. We focus our efforts on the following:

  • Increasing uptime
  • Reducing unexpected repairs
  • Reducing energy consumption
  • Improving the cleanliness of compressed air

Talk to the team today:  CONTACT US CONTACT US

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