In this article we will explain the different terminology used in compressors and how they relate to each other. We will also relate and refer to the Rayzist and ABRA Range of sandblasting machines. Let’s start with explaining the terminology.
PSI and BAR – Blasting Pressure
Amount of pressure being output by the controlled blast.
These are effectively the same thing. PSI is a micro measure of BAR like millimeters are to centimeters. They relate to the amount of force coming out of your blasting nozzle which effects the speed at which you can get depth in conjunction with the speed of the moment across the item.
PSI: Pounds per square inch (PSI) is a measurement of pressure in the Imperial system of measurement. The higher the Pressure the more bite the abrasive blasting will have. So 40psi will blast faster than 20psi at the same rate of movement.
BAR: Bar is a unit of pressure in the metric system. So, keeping this nice and simple, BAR and PSI are measuring the force of pressure of the blast from your sandblasting machine.
BAR is a bigger scale of measurement than PSI. Think of it as PSI is the millimeters of a BAR. The conversion is 1 BAR = 14.5038 PSI
The monumental industry commonly use BAR because they are basting at higher pressure such as 3-4 BAR (43.5 and 58.01 PSI)
Trophy engravers normally use PSI because they are blasting between 20 and 30 PSI (1.38 and 2.06 Bar). Because they are using low pressure they can define pressure better with PSI. Just like you do with a Vehicles air pressure of 32 or 34 psi.
CFM and FAD L/M – Air Delivery to Sandblasting System
The maximum amount of air a compressor can output per minute
CFM “Cubic Feet per minute” and FAD L/M “Free Air Deliver Litres per minute” are again the same thing just imperial and metric.
It relates to the maximum capacity of your compressor to deliver air if the blast pressure was not regulated by the sandblasting machines blasting pressure regulator.
The PB2304VXA sandblasting system compressor air delivery suggested requirement is 14cfm which equals 481 Litres per minute
The AUTOB CNC AutoBlaster compressor air delivery suggested requirement is 56cfm which equals around 1600 Litres per minute.
Here is a handy online convertor - https://www.convertunits.com/from/cfm/to/litre/min
The wider the nozzle the more Litres per minute you will need to deliver air at the pressure you have set for blasting.
This chart shows the amount of air delivery is required depending on the size of the nozzle. Let’s use a 5mm nozzle as an example.
A 5mm nozzle with a blasting pressure of 4 bars needs 1200 Litres per minute for optimal performance. When the 5mm orifice wears to 5.5mm-6mm it will need more like 1700 Litres per minute to keep the performance the same.
Tanks come in different sizes and are storage containers for the air that the compressor has generated. The bigger the tank the less times the compressor generator will switch on. If you have a small tank the compressor kicks in more as you are blasting. A larger tank and it kicks in less.
For the PB2034VXA sandblasting system a 50ltr air tank is fine. For the SM-Pro, which drives the CNC system, 300ltr to 500ltr tank is recommended.
Air compressors are rated in horsepower based on the size of the engine. The higher horsepower, the more power it will have to run larger or multiple tools simultaneously.
Hope this article helps to clarify Compressor language.