Six Indispensable Factors for Proper Air Compressor Selection
Air compressors are critical equipment providing power for production. Scientific selection and procurement are of great importance for users.
This article introduces six key considerations for air compressor selection to help you achieve energy-saving operation and deliver stable power for production.
1. Exhaust Pressure and Flow Rate
The flow rate of the selected air compressor shall match the required air consumption, with a minimum reserve margin of 10%. If the distance between air consumption points and the compressor is long, or there is a plan to add a small number of new pneumatic tools in the near future, the margin can be increased to 20%.
Insufficient compressor flow relative to air demand will lead to failure of pneumatic equipment. In contrast, excessive compressor flow against low air demand will increase the loading/unloading cycles or result in long-term low-frequency operation of the compressor, causing energy waste.
The formula for compressor selection:
Air demand = Total air consumption of all tools & equipment + Process air consumption + Air leakage + Wear loss + Future air demand × Utilization factor (1.1 ~ 1.2)
In addition, peak, normal and valley air consumption shall be taken into account when determining flow rate, as well as whether the air consumption of each workshop is stable or fluctuating.
For example: Workshop A maintains stable pressure and air consumption during production, requiring continuous compressor operation; either fixed-speed or permanent-magnet compressors are applicable. Workshop B has relatively volatile air consumption and pressure with some equipment running continuously, so permanent-magnet compressors are a better choice. If multiple workshops have uneven air consumption at different times, several small-flow compressors can be operated in parallel to meet higher total demand. Units can be started sequentially as air demand rises to save energy.
The exhaust pressure of an air compressor refers to the gauge pressure of gas discharged from the compressor, measured in MPa. The industry commonly uses "kgf/cm²" as a pressure unit, where 1 kgf/cm² = 0.1 MPa.
The exhaust pressure marked on the compressor nameplate is the rated exhaust pressure. During selection, do not only focus on the nameplate value. The entire air system must be evaluated with pressure drop and loss considered.
Generally:
Determined working pressure = End-user required pressure + Pressure drop of final filter + Pipeline system pressure loss + Particle filter pressure loss + Dryer pressure loss + Compressor adjustment margin.
List the operating pressure requirements of all equipment during selection. If pressure requirements vary greatly, air compressors with different pressure ratings shall be equipped. Do not operate equipment at reduced pressure, which will raise operating costs.
2. Energy Efficiency and Specific Power
The energy efficiency grade of an air compressor is evaluated by specific power, calculated as compressor power divided by air output.
Level 1 Energy Efficiency: Internationally advanced, optimum energy-saving performance with the lowest energy consumption
Level 2 Energy Efficiency: Relatively energy-saving
Level 3 Energy Efficiency: Average energy efficiency level for domestic market
3. Application Scenarios and Operating Conditions
Air-cooled compressors are preferred for sites with good ventilation and sufficient installation space.
Water-cooled compressors are more suitable for locations with large air demand and good water quality.
4. Compressed Air Quality
The commonly adopted standard for compressed air purity in China is GB/T13277.1-2008. Oil-free compressors generally comply with the international standard ISO 8573-1:2010.
Compressed air generated by oil-injected screw compressors contains tiny oil aerosols, moisture and fine particles. Post-processing equipment including air receivers, refrigerated air dryers and precision filters can purify the compressed air. For applications demanding superior air quality, desiccant air dryers can be equipped for further purification.
Oil-free air compressors can deliver extremely high compressed air quality. The compressed air supplied by Baode oil-free series fully meets Class 0 of ISO 8573 standard.
The required compressed air quality depends on finished products, production machines and pneumatic tools. Substandard compressed air may lead to reduced product quality or even equipment damage. Nevertheless, higher purity is not always better. Excessively high air purity will increase equipment procurement costs and waste electric power.
5. Operational Safety of Air Compressors
Air compressors operate under pressure. Air receivers with a volume above 1 cubic meter belong to special equipment, so operational safety shall be prioritized.
During selection, users must verify the manufacturer’s production qualifications to guarantee product quality.
6. After-sales Service Provided by Manufacturers
Maintenance within the warranty period is undertaken directly by the manufacturer or authorized service providers. However, unpredictable conditions may still emerge during compressor operation.
This article introduces six key considerations for air compressor selection to help you achieve energy-saving operation and deliver stable power for production.
1. Exhaust Pressure and Flow Rate
The flow rate of the selected air compressor shall match the required air consumption, with a minimum reserve margin of 10%. If the distance between air consumption points and the compressor is long, or there is a plan to add a small number of new pneumatic tools in the near future, the margin can be increased to 20%.
Insufficient compressor flow relative to air demand will lead to failure of pneumatic equipment. In contrast, excessive compressor flow against low air demand will increase the loading/unloading cycles or result in long-term low-frequency operation of the compressor, causing energy waste.
The formula for compressor selection:
Air demand = Total air consumption of all tools & equipment + Process air consumption + Air leakage + Wear loss + Future air demand × Utilization factor (1.1 ~ 1.2)
In addition, peak, normal and valley air consumption shall be taken into account when determining flow rate, as well as whether the air consumption of each workshop is stable or fluctuating.
For example: Workshop A maintains stable pressure and air consumption during production, requiring continuous compressor operation; either fixed-speed or permanent-magnet compressors are applicable. Workshop B has relatively volatile air consumption and pressure with some equipment running continuously, so permanent-magnet compressors are a better choice. If multiple workshops have uneven air consumption at different times, several small-flow compressors can be operated in parallel to meet higher total demand. Units can be started sequentially as air demand rises to save energy.
The exhaust pressure of an air compressor refers to the gauge pressure of gas discharged from the compressor, measured in MPa. The industry commonly uses "kgf/cm²" as a pressure unit, where 1 kgf/cm² = 0.1 MPa.
The exhaust pressure marked on the compressor nameplate is the rated exhaust pressure. During selection, do not only focus on the nameplate value. The entire air system must be evaluated with pressure drop and loss considered.
Generally:
Determined working pressure = End-user required pressure + Pressure drop of final filter + Pipeline system pressure loss + Particle filter pressure loss + Dryer pressure loss + Compressor adjustment margin.
List the operating pressure requirements of all equipment during selection. If pressure requirements vary greatly, air compressors with different pressure ratings shall be equipped. Do not operate equipment at reduced pressure, which will raise operating costs.
2. Energy Efficiency and Specific Power
The energy efficiency grade of an air compressor is evaluated by specific power, calculated as compressor power divided by air output.
Level 1 Energy Efficiency: Internationally advanced, optimum energy-saving performance with the lowest energy consumption
Level 2 Energy Efficiency: Relatively energy-saving
Level 3 Energy Efficiency: Average energy efficiency level for domestic market
3. Application Scenarios and Operating Conditions
Air-cooled compressors are preferred for sites with good ventilation and sufficient installation space.
Water-cooled compressors are more suitable for locations with large air demand and good water quality.
4. Compressed Air Quality
The commonly adopted standard for compressed air purity in China is GB/T13277.1-2008. Oil-free compressors generally comply with the international standard ISO 8573-1:2010.
Compressed air generated by oil-injected screw compressors contains tiny oil aerosols, moisture and fine particles. Post-processing equipment including air receivers, refrigerated air dryers and precision filters can purify the compressed air. For applications demanding superior air quality, desiccant air dryers can be equipped for further purification.
Oil-free air compressors can deliver extremely high compressed air quality. The compressed air supplied by Baode oil-free series fully meets Class 0 of ISO 8573 standard.
The required compressed air quality depends on finished products, production machines and pneumatic tools. Substandard compressed air may lead to reduced product quality or even equipment damage. Nevertheless, higher purity is not always better. Excessively high air purity will increase equipment procurement costs and waste electric power.
5. Operational Safety of Air Compressors
Air compressors operate under pressure. Air receivers with a volume above 1 cubic meter belong to special equipment, so operational safety shall be prioritized.
During selection, users must verify the manufacturer’s production qualifications to guarantee product quality.
6. After-sales Service Provided by Manufacturers
Maintenance within the warranty period is undertaken directly by the manufacturer or authorized service providers. However, unpredictable conditions may still emerge during compressor operation.
