ToolnozaUnderstand the method
Distinguish the airflow inferred from a measurement from an airflow requirement. Area × mean velocity estimates the flow through that section. For area 12 m² and mean velocity 2 m/s, Q is 24 m³/s. A single reading need not represent the cross-sectional mean; use a documented measurement method and representative section data.
Worked calculation
Compare separate personnel and operating diesel-power criteria using factors approved for the site and equipment. The displayed example factors are not legal minima. The maximum mode retains the larger criterion; additive mode sums them. Choose the convention required by the engineering basis rather than assuming either mode always establishes safe ventilation.
Practical checks
If the delivered requirement is 20 m³/s and leakage is 10% of upstream flow, divide by 0.90: upstream flow is 22.22 m³/s, not 22. Multiply m³/s by 60 for m³/min and by approximately 2,118.88 for CFM. Fan selection also needs pressure and a network assessment; this calculator does not size a fan or model contaminant dilution.
Use the free tool
Enter area and mean air velocity. Enter concurrent people, operating diesel kW and site-approved coefficients. Select maximum or additive criteria and leakage allowance.
Formula reference
Measured Q = area × mean velocity. Personnel Q = people × factor. Diesel Q = operating kW × factor. Upstream Q = selected requirement / (1 − leakage fraction).
Limits
Preliminary comparison, not a ventilation design or compliance check. Illustrative coefficients are not legal minima. Gas, dust, DPM, heat, blasting fumes, network losses and fan pressure are excluded. Validate with measurements, equipment approvals and a qualified ventilation engineer.