Air compressor air delivery calculation formula

What is the air displacement of an air compressor?

In a compressed air system, the air compressor’s air delivery rate is generally understood as the amount of air the system needs to store or buffer, and it can also be used to verify whether the volume of the air receiver tank, the air compressor’s supply capacity, and the demand of the air‑using equipment are properly matched. Before performing the calculation, it is necessary to distinguish between…Free air volume,Work stress,Permissible pressure dropandGas usage time.

Basic Calculation Formula

The commonly used estimation formula is as follows:

• Gas Storage Capacity Estimation:V ≈ Q × t ÷ ΔP
• Total gas consumption estimation:Q_total = Σ(Q_i × K_i) × K_leak × K_sim
• Displacement Verification:Q_comp ≥ Q_total × K_margin

In the formula, V Here, V denotes the gas storage tank or buffer volume, Q represents the free air flow rate, t indicates the allowable pressure fluctuation or buffering time, and ΔP signifies the permissible pressure drop. If absolute pressure is used, it can be expressed as: V ≈ Q × t × P_atm ÷ (P1_abs – P2_abs); when pressure is expressed as gauge pressure bar Indicates and atmospheric pressure is approximately 1 bar When approximating, it can be simplified to V ≈ Q × t ÷ ΔP.

Main Parameter Description

• Q: For equipment air consumption, it is recommended to standardize the conversion to free-air volume.
• t: The buffer time required for the air compressor to load, unload, or provide emergency air supply.
• ΔP: The allowable pressure fluctuation range of the system.
• K_i: Operating condition utilization factor for a single piece of equipment.
• K_leak: Pipe leakage and loss coefficient.
• K_sim: Coefficient for simultaneous use of multiple devices.
• K_margin: Selection or capacity margin factor.

Calculation steps

• Calculate the rated gas consumption of all gas‑using equipment.
• Determine the simultaneous utilization factor and the leakage coefficient based on actual operating conditions.
• Calculate the total gas consumption of the system.
• Calculate the gas storage volume based on the allowable pressure drop and buffer time.
• Verify the air supply capacity by considering the compressor’s discharge characteristics and site-specific conditions.

Precautions for Use

When performing calculations, ensure unit consistency, and clearly specify whether pressure parameters are gauge or absolute. If the system involves intermittent high flow rates, long pipeline runs, frequent start–stop cycles, or stringent steady‑state pressure requirements, appropriately increase the design margin and verify the results using field operating data.