Calculation of air consumption in assembly workshop

The calculation of air consumption in the assembly workshop needs to comprehensively consider multiple factors such as pneumatic tools, conveying systems, leakage volume and spare volume. The following are the detailed calculation methods and steps:

1. Basic framework for gas consumption calculation

Total air consumption = air consumption of pneumatic tools + air consumption of conveying system + leakage + spare volume

2. Calculation of air consumption of pneumatic tools

1. Cylinder air consumption formula：

Q=0.046D2v(p+0.1)

• Q: Cylinder air consumption under standard conditions (L/min)
• D: Cylinder diameter (cm)
• v: Cylinder speed (mm/s)
• p: Operating pressure (MPa)

2. Pneumatic valve air consumption：
   • Regulating valve: approximately 1Nm3/h
   • Switch valve: approx. 2Nm3/h
3. other pneumatic tools：
   • According to the air consumption statistics provided on the equipment nameplate or technical manual.

3. Calculation of air consumption of the transportation system

1. calculation formula：

Qv​=ρa​⋅Qa​⋅k

• Qv​: Volume flow (m³/min)
• ρa​: Air density (usually taken 1.2kg/m3）
• Qa​: Air mass required per minute (kg/min)
• k: Air leakage coefficient (usually 1.1~1.2)

2. key parameters：
   • Grey-gas ratio (μ): The ratio of material mass to air mass is usually 7 – 20 kg/kg.
   • Air leakage coefficient (k): Select 1.1~1.2 based on system tightness.

4. Considerations on leakage volume and reserve volume

1. leakage：
   • Leakage from the compressed air system may reach 20% to 40% of the air supply.
   • recommendations: Regularly inspect and repair leakage points to control the leakage rate within a reasonable range.
2. reserve capacity：
   • Generally, an abundance factor of 10% to 20% is increased when calculating the total air consumption.

5. Calculation examples

Suppose an assembly shop has the following equipment:

• cylinder: Cylinder bore D=5cm, speed v=200mm/s, pressure p=0.5MPa
• regulating valve: 2 units, each unit 1Nm3/h
• switch valve: 1 unit, each unit 2Nm3/h
• delivery system: Delivery volume per hour G=10t/h, grey-to-gas ratio μ=15kg/kg

calculation step：

1. cylinder air consumption：

Q=0.046×52×200×(0.5+0.1)=165.6L/min

2. valve air consumption：

   • Regulating valve:2×1Nm3/h=2Nm3/h
   • Switch valve:1×2Nm3/h=2Nm3/h
   • Total valve air consumption：4Nm3/h≈0.067m3/min

3. Air consumption of conveying system：

   • Qa​=ash-gas ratioG×60×μ​=110×60×15​=9000kg/min
   • Qv​=1.2×9000÷1.2=9000m3/min (Consider air leakage coefficient)

4. total air consumption：

165.6+0.067+9000=9165.73m3/min

5. Consider reserve：

9165.73×1.2=11000m3/min

6. Summary

• key step: Count the air consumption of all equipment → calculate the transportation system demand → consider leaks and spare volume → determine the air compressor selection.
• recommendations: Regularly inspect and optimize systems to reduce leaks and improve energy efficiency.