What is the appropriate gas flow rate for general factory gas?

The appropriate gas flow rate for plant gas needs to be determined based on a combination of specific equipment requirements, process requirements and future scalability, the core principle is that the total gas consumption should cover the gas demand of all equipment in use and reserve 20% allowance.. The following is a specific analysis:

core basis for 1. gas flow demand

1. total gas consumption of equipment
   count the rated gas flow of all gas-using equipment (unit: m & sup3;/min), for example:
   • pneumatic tools: 0.3-0.8m & sup3;/min;
   • spraying equipment: 0.5-1.5m & sup3;/min;
   • laser cutting machine: 2-5m & sup3;/min (adjusted according to power and cutting material thickness).
     Total gas consumption = sum of rated gas flow of all equipment × 1.2 (reserve 20% margin).
     Example: If the factory has 3 pneumatic tools (each 0.5m & sup3;/min) and 1 spraying equipment (1m & sup3;/min), the total gas consumption = (3 × 0.5+1) × 1.2=3m & sup3;/min.
2. Process parameter requirements
   • pressure matching: The air flow shall be considered in coordination with the pressure required by the equipment. For example, the pneumatic punch press needs 8bar pressure, if the gas flow is insufficient, the pressure will drop, affecting the stability of the action.
   • Dynamic demand if the gas consumption fluctuates greatly (such as high load during the day and low load at night), the variable frequency air compressor should be selected to automatically adjust the air flow according to the actual demand, and the energy saving effect can reach 30%.
3. Future expansion
   • when the factory expands or adds new equipment, the air flow should be reserved for 10%-20% redundancy to avoid frequent replacement of air compressors.
   • Case: a factory initially selected 5m & sup3;/min air compressor, then the gas consumption increased to 7m & sup3 due to the new production line;/min, forced to install a 3m & sup3;/min model, increase cost and energy consumption.

2. air flow and air compressor selection

1. air compressor type and air flow range
   • piston air compressor: Suitable for small factories, air flow ≤ 3m & sup3;/min, low initial cost but high noise and frequent maintenance.
   • Screw air compressor: Suitable for medium and large factories, air flow 3-100m & sup3;/min, high efficiency, low noise, easy maintenance.
   • Centrifugal air compressor: Suitable for large-scale industrial projects, air flow ≥ 100m & sup3;/min, high initial investment but stable operation.
2. Selection formula
   • air flow (m & sup3;/min): Select the model with rated gas flow ≥ calculated value according to the total gas consumption.
   • Pressure (MPa): According to equipment requirements, such as pneumatic tools usually need 0.6-0.8MPa, laser cutting needs 1.2-1.6MPa.
   • Example: total gas consumption is 3m & sup3;/min, the pressure needs to be 0.8MPa, screw air compressor can be selected (rated air flow 3.5m & sup3;/min, pressure 0.8MPa).

Practical Suggestions for 3. Gas Flow Optimization

1. reduce leakage
   • system leaks may result in insufficient gas flow, requiring periodic inspection of piping, valves and joints.
   • Data: A 1/4 inch small hole may leak 2.8m & sup3 under 0.7MPa pressure;/h compressed air, equivalent to the loss of an 18.75kw air compressor.
2. Pipeline Design Optimization
   • the main pipe diameter shall be calculated according to the gas flow and distance to avoid excessive pressure drop.
   • Formula: Pressure drop & Delta;P = (& lambda; ×L× & rho; ×v²) / (2 ×D), where & lambda; is the friction coefficient, L is the pipe length, & rho; is the gas density, v is the flow rate, and D is the pipe diameter.
   • Recommendations: When the air flow is large (such as ≥ 10m & sup3;/min), the diameter of the main pipe is recommended to be ≥ 100mm, and the number of elbows and valves should be reduced.
3. Time-divided gas supply
   • for factories with large fluctuations in gas consumption, a time-by-time gas supply strategy can be adopted, such as starting multiple air compressors during the peak of gas consumption during the day and keeping only one compressor in operation at the trough at night.

4. airflow reference for typical scenarios