How is the capacity of a compressed air system calculated? Key factors include air consumption, storage capacity, pressure drop, and compressor selection.

I. Accurately assess the system’s total gas consumption.

Air consumption is the foundation for sizing a compressed air system. When calculating total air consumption, several factors must be taken into account:

• Rated gas consumption of the equipment: Calculate the total rated air consumption of all pneumatic equipment, cylinders, and pneumatic tools.
• Simultaneous use coefficientNot all equipment will operate at full capacity simultaneously; a reasonable simultaneous-use factor should be applied based on actual operating conditions.
• Pipeline network leakage volume: Older pipeline networks or poorly maintained systems are prone to leaks, which typically require allocating a certain percentage of the total gas consumption as a leakage allowance.
• Future capacity expansion margin: Consider the enterprise’s future capacity planning and reserve an appropriate margin for gas consumption.

II. Reasonably Determine the Volume of the Gas Storage Tank

The gas storage tank serves to buffer pressure, stabilize system pressure, and provide preliminary cooling. The calculation of the required gas storage capacity shall adhere to the following principles:

• Match the air compressor’s displacementIt is generally recommended that the air receiver tank capacity be a specific multiple of the air compressor’s discharge rate to dampen airflow pulsations.
• Peak Gas Demand ManagementIf the system experiences short-term peak gas consumption, the storage tank capacity should be appropriately increased to ensure sufficient buffer gas is available before the air compressor is loaded.
• System stability: Larger air storage tanks help reduce the frequent cycling of the air compressor, thereby lowering energy consumption and extending equipment service life.

III. Precise Calculation of Pipeline Network Pressure Drop

Pressure drop directly affects the normal operation of terminal equipment, and the system’s total pressure drop consists of the following components:

• Frictional resistance along the pipelineIt is related to pipeline length, pipe diameter, internal wall roughness, and gas flow velocity. During design, the pipeline should be kept as short as possible, the number of bends minimized, and an appropriate pipe diameter selected to reduce flow velocity.
• Local resistance: Pressure losses caused by pipe fittings such as valves, elbows, and tees. Local resistance can be reduced by optimizing the piping layout.
• Pressure drop of the aftertreatment device: Aftertreatment equipment such as filters and dryers incurs a certain pressure drop; the total pressure loss should be calculated by summing the values provided in the equipment manufacturer’s technical specifications.

IV. Scientific Host Selection

The selection of the host directly determines the system’s energy efficiency and stability, and the following parameters should be given particular consideration:

• Displacement matchingThe air compressor’s rated displacement must be equal to or greater than the system’s calculated total air consumption, to prevent the equipment from operating continuously at full load or overload.
• Exhaust pressure settingThe rated discharge pressure of the air compressor should equal the maximum demand pressure of the terminal equipment, plus the total pressure drop in the piping network and the pressure drop across the downstream treatment equipment. Setting the pressure too high will result in energy waste.
• Combination of variable frequency and mains frequencyFor systems with significant fluctuations in air consumption, it is recommended to use variable-frequency air compressors as peak‑shaving equipment and line‑frequency air compressors as the base load, thereby achieving optimal energy savings.