How to choose an air compressor for the industry?
To properly select your air compressor, you must first determine how often it will be used, depending on the compressed air requirement of your application.
You also have to determine whether it should be mobile or permanently installed. In this case, you need to make sure that the compressor is well ventilated to ensure optimal cooling.
Another important element to keep in mind is the continuous operating time of your compressor. Manufacturers usually specify a duty cycle for their products. It determines how long the compressor can be operated within an hour. A compressor with a duty cycle of 30% can only be operated for 18 minutes and then has to cool for 42 minutes.
Compressed air compressors enable the use of various portable compressed air tools: hammers, nailing devices, pneumatic screwdrivers, pneumatic hammers, compressed air guns, paint atomizers, sandblasting devices, etc. Look more articles: Air Compressors For Impact Wrenches, best 80 gallon air compressor, best 60 Gallon Air Compressor, best 30 gallon air compressor. Best Portable 110v Air Compressor For Tires and Best 120v Air Compressor For Car Tires.
Stationary or mobile air compressors can e.g. can also be used in industry or agriculture:
- For air tools in production lines
- For blow molding bottles or gas containers
- For the air supply in pneumatic cylinders
- For sandblasting metal parts
- For spraying cultures
- For ventilation of greenhouses etc.
What is the recommended size for your compressor?
To determine the size of your compressor, you first need to know the maximum pressure you need. It is defined via the properties of the devices or the compressed air circuit (industry or agriculture) from which the compressor is supplied. It can be expressed in pounds per square inch (psi), bar, or pascal (Pa). Depending on the pressure, you need a single-stage (maximum 135 psi or 9 bar) or a multi-stage compressor, the latter increasing the pressure significantly (maximum 5,800 psi or 400 bar).
You should still know the maximum throughput that you need. The volume flow represents the amount of air available to supply the various devices that must be connected to each other on the compressor. It can be specified in cubic feet per minute (cfm), liters per second (l / s) or cubic meters per hour (m3 / h). Therefore, without oversizing the compressor, it is better to plan a safety margin of approx. 30% of the estimated need in order to avoid unpleasant surprises. Look more: How To Use Air Compressor.
The performance of the compressor depends on the desired air volume and the outlet pressure. If a compressor with high nominal output but a low flow rate is designed, it is intended for occasional use and its cooling requires long pauses.
Compressors usually have a compressed air tank, which makes it possible to start the engine according to the compressed air requirement. You must calibrate this tank correctly so that the engine is not constantly loaded. Some compressors are available with a vertical tank, which reduces their space requirement when installed in confined spaces.
How To Use Air Compressor?
Read more tips: Using an air compressor
Choosing a compressor
Most compressors are positive displacement compressors: a mechanism reduces the volume of air to compress it. These compressors are usually driven by electric motors.
Piston compressors. These compressors can be single-cylinder. The pressure of this type of compressor can rise to 10 bar. The same type of compressor can also be multi-stage: the pressure is increased in stages and can reach up to 400 bar. You can choose this type of compressor if you are looking for an intermittent function: the duty cycle is a maximum of 60%, i.e. he can only work 35 minutes an hour. The compressed air reserve must be sufficient in relation to the estimated volume flow so that the compressor does not have to be operated more often. Another potential problem with this type of compressor is that it also emits oil with the compressed air. If the required air needs to be clean, you need to provide a filter system or choose an oil-free compressor (this is the case, for example, in the electronics, pharmaceutical, food or clean room industries). In addition, piston compressors are relatively loud, which is a nuisance for people working nearby.
Screw compressors. It is the most commonly used model in the industry. It uses augers instead of the piston. The pressure obtained can vary from 5 bar for a single cylinder model to 13 bar for a multi-stage model, this type of compressor generally offers a high flow rate and a high compression ratio with a single stage, which enables manufacturers to offer compressors with reduced dimensions, in contrast too with a similar piston model (which should be multi-stage to offer the same pressure).
The screw compressor can have a duty cycle of 100% and can therefore be operated continuously. Some screw compressors are speed controlled. You can adjust their speed to the respective compressed air requirement and thus optimize their energy requirements.
Rotary compressors Here, pallets (plates) slide in an eccentric rotor and compress the air. The energy efficiency of these compressors is generally attractive. At the same pressure and the same flow rates, these compressors have a lower speed than screw compressors, which reduces the wear of the parts and the maintenance effort and thus increases the service life. They are used in various fields of activity such as the printing, wood and packaging industries. In industries that need clean air, such as in the field of energy or medicine, many models are available without oil.
Centrifugal compressor. In these compressors, the air is drawn through the machine using a paddle wheel; the principle is the same as that of the turbocharger in the automotive industry. They are generally used when a continuously high flow at high pressure is required, which is particularly the case in energy production and in the chemical industry. These compressors are usually equipped with an integrated reducer to regulate flow and pressure at optimal speed. These compressors are generally equipped with a reduction gear so that the engine can operate at optimal speed. You can achieve a throughput of up to 500,000 m3 / h, and this at a pressure of 200 bars.
Compressors are divided into three main groups:
Stationary compressors These are fixed machines. They are generally very powerful and offer both high flow and pressure.
Mobile or semi-stationary compressors. They generally have properties similar to stationary monoblock compressors, but can be relocated to different areas (e.g. construction sites). Their base is generally designed for the passage of the forks of a forklift. These compressors are generally equipped with an internal combustion engine.
Portable compressors. Generally, they are not intended for intensive use, but they have the advantage that they are very easy to move.
In which cases is an oil-free compressor suitable?
Some compressors are available without oil, so the exhaust air is clean. They are therefore environmentally friendly and less harmful. They are primarily used in the electronics industry, including semiconductor manufacturing, pharmaceuticals, chemistry, medicine, automotive assembly or refinement, and food processing.
If you need to choose an oil-free compressor, make sure that it complies with ISO Class 8573-1, as this is the only class that ensures complete oil-free operation. The upper classes determine the maximum amount of oil in the compressed air, which usually requires the use of an air dryer. These compressors, which do not offer very high pressure values, are usually not designed for intensive use.
In the case of a piston compressor, the lubrication can be replaced by a Teflon or silicone coating that protects moving parts. This can also be replaced by water that is injected or circulated in a closed circuit. The noise generated by these compressors is often stronger, but they require less maintenance.
What motors are used for compressors?
The most economical compressors are equipped with electric motors, but they are also the least powerful, especially if they are supplied with single-phase energy. The market also offers compressors that are powered by internal combustion engines (diesel or petrol). Compressors equipped with an internal combustion engine are generally intended for outdoor use because of their exhaust gases.