EVAP System Flow Calculator

Calculate evaporative emissions system flow rates, canister capacity, and purge valve requirements for fuel vapor management.

Input Parameters

Results

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Vapor Generation Rate
g/hr
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Canister Capacity
g
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Time to Saturation
hrs
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Required Purge Time
min
Note: EPA requires zero evaporative emissions (Tier 3). EVAP leak detection uses 0.020" and 0.040" orifice tests. Canister must handle diurnal and refueling vapors.

Reference

Vapor Rate = Tank x RVP x 0.002 x (1 + 0.04 x (T - 25)) Canister Capacity = Volume x Carbon_density x Loading_factor Saturation Time = Capacity / Vapor Rate Purge Rate = Purge Flow x Air_density x HC_concentration Purge Time = Stored Vapor / Purge Rate