How to calculate the hourly compressed air consumption of the equipment

The calculation of the hourly compressed air consumption of the equipment shall comprehensively consider the factors such as equipment parameters, operation mode, system efficiency and actual working conditions. The following are the specific calculation methods and steps:

1. Foundation Formula

compressed air consumption (Nm & sup3;/h) = theoretical air consumption of equipment × operating coefficient × leakage coefficient
or
compressed air consumption (Nm & sup3;/h) = air consumption per unit time (e. g. per cycle/minute) × number of cycles per unit time × 60

2. detailed calculation steps

1. Determine the theoretical air consumption of the equipment

• pneumatic tools/actuators:
  consult the equipment manual to obtain air consumption per unit time(e. g. air consumption per minute/cycle in Nm & sup3;/min or Nm & sup3;/cycle).
  Example: pneumatic wrench consumes 0.05 Nm & sup3 per minute;, the air consumption per hour is 0.05 × 60 = 3Nm & sup3;/h.

• Cylinder/pneumatic valve:
  according to the cylinder volume, frequency and pressure calculation:

single air consumption = 4 & pi;D2 ×S× 10.1325P +1

• d: Cylinder diameter (m)

• s: stroke (m)

• p: working pressure (bar, absolute pressure need to add 1 atmosphere)

• the result is expressed in Nm & sup3;/cycle and multiplied by the number of cycles per hour to obtain the total gas consumption.

• Spray gun/purging equipment:
  based on nozzle flow and opening time:

air consumption = nozzle flow (Nm & sup3;/min)× opening time (min/h)× 60

2. Consider the operating coefficient

• continuous operation equipment: The operating coefficient is 1 (such as a pneumatic pump that works continuously for 24 hours).
• Intermittent operation equipment: Adjust according to the proportion of actual running time (for example, the equipment runs for 30 minutes per hour with a coefficient of 0.5).

3. Correcting leakage and system efficiency

• leakage coefficient: Usually 1.1~1.3 is used to compensate for leakage losses of pipelines, valves, etc.
• system efficiency: If the compressed air needs to be dried, filtered, etc., an additional 5% to 10% air consumption may be required.

3. practical cases

case 1: Pneumatic Punch

• air consumption per ram: 0.02 Nm & sup3;/cycle

• stamping times per hour: 1200 times

• operating coefficient: 0.9 (due to equipment shutdown occasionally)

• leakage coefficient: 1.2

• calculation:

0.02×1200×0.9×1.2=25.92Nm³/h

case 2: Pneumatic spray gun

• nozzle flow rate: 0.5 Nm & sup3;/min

• spraying time per hour: 20 minutes

• leakage coefficient: 1.1

• calculation:

0.5×20×1.1=11Nm³/h

4. considerations

1. unification of units: Ensure that all parameter units are consistent (e. g. pressure is converted to bar or MPa, length is converted to meters).
2. Working condition difference: High temperature, high pressure or low temperature environment may affect gas consumption, which shall be adjusted according to actual working conditions.
3. dynamic change: Equipment aging or load changes may cause fluctuations in air consumption, and regular monitoring is recommended.
4. Standby quantity: When designing the compressed air system, a margin of 10% ~ 20% should be reserved to meet the peak demand.

5. simplification method

if the equipment manual is provided directly air consumption per hour(If a pneumatic drilling rig is marked as 8 Nm & sup3;/h), no complicated calculation is required, but it needs to be multiplied by the operating coefficient and leakage coefficient correction.

Through the above steps, the hourly compressed air consumption of the equipment can be accurately estimated, which provides the basis for compressor selection and system design.