Air compressor what do you need?

Air compressor do you need?

When choosing your air compressor there are four main things to look at:

  1. The amount of air you need. This is measured in cubic feet per minute CFM (or M3/min) and can be worked out by looking at the tools or machinery you are using with your compressor and the amount that they each consume.
  2. The operating pressure you will need in PSI (or KPA) and the quality of air. Again, this will be based on the tools and equipment that you are using with your compressor.
  3. How often do you need air? Is it 24/7 or are you only using it off and on.
  4. Where is the compressor going to be based is it stationary with electricity available or does it need to be portable?

 

Air Consumption – Your want your compressor to be sized right for what you are doing.

Look at the tools and equipment that you will be using and work out the total CFM and their operating pressure (PSI). This should be started in the manual or specifications of the equipment you are using. If you are replacing your compressor, make sure you double check all of this and do not just go with what you had as it might have been wrong the first time.

For this example, we will use a sandblaster with a ½” nozzle. If we want to use his at 100 psi we will need an screw air compressor that can supply at least 340 CFM. In addition, we will be running a mask for breathing air some of the time, so we need to add an extra 2CFM to cover this.

 This is when you look at the Free Air Delivery (FAD) of air compressors. So, for the above example you will need a compressor with FAD of at least 342CFM. You can see our range here

Gardner Denvar offer some very competitively priced air compressors in Australia and you can check out more of their range here.


Compressor Air Pressure & Quality of the Air

Once again look at the specifications of the equipment and tools you are using to determine the pressure of air you need. If you have multiple items that require different air pressure, then you can use a compressed air regulator to adjust and lower the pressure of air supplied to that certain item.

So, it is important to match the air pressure you need to that of the tool or equipment that has the highest air pressure needed as you can regulate the air to a lower pressure, but you cannot increase the pressure.

Compressed Air Quality

Compressors produce air that will have containments in it. This comes in forms of dust, moisture and oil. Depending on what equipment you are operating will decide how clean and dry you need your compressed air to be.

There are certain filters, dryers and aftercoolers you can add to your compressor to ensure you produce the quality of air you need. Contact our experienced team to ensure you get the correct equipment you need.

Back to our sand blaster example we need a compressor that can supply 100psi however at times we may need to work at a higher pressure, so we check the specifications of our equipment and see the max they can handle is 140psi. So, we will get a compressor that can produce up to this pressure as we may need to use higher pressure in the future.

Next, look at the quality of air we need. For sand blasting this can vary depending on the environment and media used. However, in this case we want reasonably dry and oil-free air, so the media does not clog up. Also, we will need breathing air from this same compressor as the user of the unit will be wearing a mask to ensure they do not breath in the media.

Compressed Air breathing setup

For all this we will need a refrigerant dryer that can handle the air flow we need which is 340CFM. Then will also need filters both on the sand blasting compressed airline and the breathing airline. See our range of filtration options 

Usage

This will depend on how often your equipment is running. It may be tools that require large volumes of air but only for a short amount of time or packaging equipment that doesn’t use a large amount of air but is running 24/7.

Most compressor push air into a pressure vessel and this is where it is stored. The compressor keeps forcing air in until the upper pressure limit is reached and then the air compressor shuts off. When the pressure gets down to a certain level as the air is used then the air compressor will turn back on and re-pressurise the air receiver. This is the air compressors cycle.

The ratio between the pressurisation and cool down phases is called the Duty Cycle. Ideally to maximise a compressor’s operational life it’s duty cycle over any given timeframe should be no more than 60% of the time turned on and 40% turned off (cooling down).

If you think you’ll be using high air consumption tools in a continuous manner, consider a compressor with a higher FAD rating and/or larger storage tank to reduce the risk of wearing out or overheating the unit.

Where is your compressor located?

This will determine what type of compressor you will need. For a further break down of the different air compressors please see this article.

These are the questions you need to think about:

Do you need it to be portable or will it be based in a stationary location?

Do you have the power at your site to power your compressor? If you do not, then you will most likely have to go for a diesel air compressor.

What size tank do you need? If you air consumption is going to be below 120CFM then you can most likely go with a complete unit which you can see here. If not or you have a high air usage you will have to go for a larger receiver tank.

You will need to make sure you have adequate room and there is good ventilation, so the compressor does not overheat.

Back to our example we are setting up the sandblasting unit in a workshop so it will be stationary and we have a 3 phase power supply . In this case in is a new workshop setup and we have other air tools around the workshop that we want to run of the compressor so we will go with a stand alone compressor, receiver tank, dryer and filtration. The compressor used will be a 75kW -470CFM.

compressed air system setup 

Hopefully Nessco Pressure Systems have provided a brief overview on what air compressor to choose. For any other questions please get in touch with us as we are the compressed air people to talk to in Perth, Western Australia.

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