How much is the air compressor used and how to calculate the air consumption

The selection of air compressors and calculation of air consumption require comprehensive technical requirements, economy and energy efficiency optimization. The following are the specific methods:

1. Key steps in air compressor selection

1. Matching flow and pressure

• flow calculation: Count the maximum flow rate of all gas equipment (unit: m³/min) and increase the margin by 20% to meet peak demand.
• pressure selection: The working pressure needs to be 1-2 bar higher than the maximum pressure of the pneumatic system (considering pipeline pressure loss). For example, when the equipment requires 7 bar, it is recommended to choose an 8-9 bar air compressor.

2. Compression ratio and energy efficiency

• compression ratio formula：

compression ratio=P1​P2​​

（P2​For exhaust pressure,P1​is the intake pressure, usually atmospheric pressure 1 bar)

• selection principle: The larger the compression ratio, the higher the energy consumption. The economic range needs to be selected based on the equipment usage frequency and power cost.

3. System comprehensive evaluation

• pipe layout: Reduce right-angle elbows and give priority to large diameter pipes (reduce pressure losses).

• leak test: Calculate the leakage amount through the air storage tank pumping test, formula:

leakage=90×Pa​V×(P2​−P1​)×60​

（Vis the volume of the gas storage tank,P2​−P1​For pressure difference,Pa​atmospheric pressure)

2. Gas consumption calculation formula

1. underlying formula

gas consumption=(working pressure+pipeline loss+amount of redundancy)×flow

• example: If the equipment requires a pressure of 7 bar, a pipe loss of 1 bar, a redundancy of 1 bar, and a flow of 10 m³/min, then:

gas consumption=(7+1+1)×10=90m³/min

2. Compression ratio correction formula

gas consumption=gas density×compression ratioworking pressure×flow​

• parameter description: The gas density is 1.2 kg/m³ (air), and the compression ratio is queried through the air compressor performance curve.

3. Calculation considerations

1. device characteristics

• simultaneity coefficient: When multiple devices are connected in parallel, the overlap ratio of gas consumption time needs to be considered (usually 0.6-0.8).
• load rate: Calculate the proportion of average equipment running time (such as 20%-60%) to avoid excessive selection.

2. Redundancy and expansion

• leakage redundancy: Increase the margin by 5%-10%(annual loss of 1/4 inch leak point is about 60,000 yuan).
• future expansion: Reserve 10%-15% of capacity to cope with production capacity growth.

3. environmental adaptability

• temperature correction: High temperature environments need to increase the flow rate (1℃ per liter of temperature, the gas volume decreases by 0.5%).
• altitude correction: Pressure needs to be increased in high-altitude areas (per liter at altitude of 1000 meters, the pressure drops by about 1%).

4. Practical suggestions

1. Evaluation of existing systems

• pumping test: Close the air storage tank valve, record the time required for the pressure to rise from 0.48 MPa to 0.69 MPa, and calculate the actual air consumption.

2. long-term planning

• demand forecast: Combine historical data and production expansion plans to reserve a modular expansion interface.

3. energy efficiency optimization

• waste heat recovery: Use air compressor waste heat (accounting for 80% of energy consumption) to drive the lithium bromide refrigerator to reduce energy consumption costs.

Through scientific selection and gas consumption calculation, the phenomenon of “big horses and small cars” can be avoided, equipment life can be extended, and energy consumption costs can be reduced.