How to calculate the gas consumption of a workshop

Technical specifications for calculation of air consumption in the compressed air system in the workshop

As the core power source of industrial production, the compressed air system directly affects equipment selection, pipe network design and energy management. Based on the practical experience of the industry, the calculation method and key elements of the workshop gas consumption are explained as follows:

1. Basic calculation method

1. Superimposition method for rated flow of equipment

• Collect the nameplate parameters of all gas equipment and arithmetically add the rated flow rate (m ³/min)
• Example: The SMT workshop includes 6 SM482 mounters (0.26m ³/min/set) and 12 SM471 high-speed machines (0.3m ³/min/set). The basic flow rate is: 6 × 0.26 + 12 × 0.3 = 5.16m ³/min

2. safety factor correction

• New equipment: total flow × 1.2 (considering capacity expansion in the next 12 – 18 months)
• Existing system: total flow × 1.1 (compensation for pipe network leakage and pressure loss)
• Special process: When high-load conditions such as vacuum adsorption and sandblasting are involved, an additional 20 – 30% flow reserve is needed

II. Verification method of actual measurement

1. Gas Tank Test Method

• Record parameters: Tank volume V (m³), Pipeline volume Vp (m³), Atmospheric pressure Pa (0.1MPa)
• Operation steps:
  ① Close the air supply valve and reduce the system pressure to 0.48MPa
  ② Start the full load operation of the air compressor and record the time T (seconds) required for the pressure to rise to 0.69MPa
  ③ Calculate the actual flow rate: C = (V+Vp)×(P2-P1)×60/(T×Pa)
  Where: P2=0.69+0.1=0.79MPa(A), P1=0.48+0.1=0.58MPa(A)

2. Leakage detection

• Night pressure maintenance test: Record the system pressure drop rate after production shutdown
• Calculation formula: Leakage = (V+Vp)×(ΔP/Δt)×60
  When the pressure drops from 0.69MPa to 0.62MPa takes more than 900 seconds (15 minutes), the leakage is less than 5% of the rated flow

3. Key correction parameters

1. altitude correction factor

• Below 1000 meters above sea level: flow does not need to be corrected
• Altitude 1,000 – 2,000 meters: flow needs to increase by 5-8%(to compensate for the decrease in air density)

2. temperature correction coefficient

• When the ambient temperature is>40℃, the flow demand increases by 0.5% for every 1℃ increase
• Low temperature environment (<5℃) needs to consider air compressor preheating energy consumption and pipeline anti-freezing measures

3. load fluctuation coefficient

• Three-shift production: Set 20-30% traffic redundancy
• Intermittent gas equipment (such as laser cutting): A special air tank needs to be equipped to balance the load

4. System configuration recommendations

1. Gas storage tank volume design

• Basic configuration: 30-50% of total traffic
• Pulse load condition: configured at 1.5 times the maximum single equipment flow
• Case: When there is a 3m³/min pulse gas equipment in the system, it is recommended to configure a 4.5 m ³ air storage tank

2. Pipe diameter selection principles

• Main pipeline flow rate control: 15-20m/s (economic flow rate range)
• Pressure drop control: pressure drop of single branch pipe ≤0.02MPa
• Quick conversion: DN80 piping (3-inch) can safely transport 4.5m³/min compressed air

5. Energy efficiency optimization measures

1. staged gas supply system

• High-pressure equipment (>0.7MPa): equipped with special air compressor unit
• Low-pressure equipment (<0.5MPa): Air supply is provided through pressure reducing valve to avoid pressure increase in the entire system

2. intelligent control system

• Configure pressure and flow joint control device to realize coordinated operation of multiple air compressors
• Typical energy-saving effects: It can reduce no-load energy consumption by 30-50%

Enterprises should establish a dynamic monitoring system for gas consumption, and carry out quarterly system energy efficiency assessments in conjunction with the GB/T 16665 “Energy Saving Monitoring Methods for Air Compressor Units and Gas Supply Systems” standard. It is recommended to use ultrasonic flowmeters to conduct annual pipe network surveys, focusing on checking core indicators such as flow deviation (≤±3%), pressure stability (≤±0.02MPa), and leakage rate (≤5%), and continuously optimizing the quality of system operation. Reduce comprehensive energy costs.