One of the biggest challenges is to correctly size your new air compressor. Similarly to everything else, new compressors available on the
market are more efficient and employ better technology, therefore you have to understand the application and usage to size the machine
correctly. Choosing the wrong air compressor for your facility can lead to problems with production and or increased costs due to wasted
What amount of pressure do I need?
Understanding the flow and pressure requirements for your facility is key when choosing an air compressor. Pressure and flow are two very
common terms used when discussing compressed air systems.
Pressure can be measured in pounds per square inch (psi), or bar (metric measure of pressure). To think of this in simpler terms,
pressure refers to the amount of force needed to perform certain amount of work at any given point in time. A simple example
of pressure and how it works, is to imagine moving a wooden block across a table. In the illustration below, it shows that
using 75 psi of compressed air is not enough force to move the block, but 100 psi of pressure has the ability to move the
wooden block the desired distance.
The air compressor has to provide enough pressure to perform a given task (in this case it was to move a wooden block). Per illustration
below, if 100 psi is required to move the block, anything less than that will not accomplish the task. It is important to
understand what pressure is needed in order to size the compressor properly, otherwise you will be faced with problems, similar
to illustration below where lower pressure was not able to move the wooden block, or perform the job.
What is the right air flow for my compressor?
Flow, also referred to as Free Air Delivery (FAD) can be measured in cubic feet per minute (cfm), liters per second (l/s) or cubic meters per hour
(m3/h) depending on your geographical location. In simpler terms, flow is the ability of the compressor to continue performing a task within an acceptable
time frame. The amount of flow required is determined by the length of time needed to complete a given task. Let us consider the wooden block example
to explain this further.
To move a wooden block a certain distance every hour will require less flow and can be achieved with a smaller compressor and a storage
tank. The compressor will cycle on and off and refill the storage tank for the next time the wooden block is required to move. However,
if the wooden block has to be moved constantly within a given time frame, a larger flow of air (or CFM) with continuous flow will be needed,
thus requiring a larger compressor. If the flow is insufficient, the process will require frequent breaks while the compressor builds up
pressure in the reserve tank, therefore indicating that the compressor might be undersized.
Ultimately, when you are looking to supply enough compressed air for a given application, it is important to consider the amount of compressed air flow
(CFM) needed at a specific pressure (PSI) required for the process to work properly.
One of the ways to find out the total flow needed is to contact the manufacturer of the equipment that uses compressed air and request data sheets with
desired information. However, the best way to measure accurate flow, is to perform a “compressed air audit”, which can be done by a compressed air
sales professional. It is important to keep in mind that rotary compressors tend to put out more flow per kW or HP than piston.
To summarize, pressure (PSI) is determined by the job you are performing, while flow (CFM) will require the understanding of how frequently the job has
to be done, or how many jobs you are performing at the same time. It is important to understand that under sizing a compressor will result in pressure
drops and inability to complete a task, while oversizing the unit can lead to future mechanical problems and potential failure of the compressor. If
you are unsure on how to size your new compressor for existing or new application, always contact a compressed air sales professional for an
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
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:
A common questions asked is why do I need an air dryer for my compressor? Typically, air compressors produce water, and although the
water can be drained, there can still be aerosol and vapour droplets that are present. This is because water cannoet be compressed. Water
can damage your compressor by corroding the valves, pipes and machinery controls, which will cost you time and money to resolve. In
the long run, the cost of a new compressor is a small price to pay compared to the loss of production that could potentially arise due
to water damage in your compressor.
That cold, rainy, and in some places icey New Zealand winter is upon us, and with the following air compressor tips, your air system will be
prepared with the preferred temperatures, despite the weather outside. Regardless of whether or not it actually snows or freezes up where
you live, most winterisation service recommendations are also basic, solid maintenance procedures that will help extend the life and
operational efficiencies of air compressors regardless of whether you live in Queenstown or Northland.
Air compressors can fail for an assortment of different reasons: Normal wear and tear, lifespan and age of the unit, poor maintenance, power surge, install issues are just a few the come to mind. Check out this blog to find out our top 7 tips to ensure your compressor is looked