Flare Disposal System Calculator
Sizes flare headers and knockout drums for safe disposal of relief loads. Accounts for two-phase flow, pressure drop, and elevation changes per API RP 521 disposal system guidelines.
Calculation Mode:
Header Parameters
in
psi
ft
Knockout Drum
min
Flow & Gas Properties
lb/hr
lb/ft³
Pressure Drop Results
Total Drop
- psi
Velocity- ft/s
Mach Number-
Header Sizing Results
Required Diameter
- in
Standard Diameter- in
KO Drum Sizing Results
Drum Diameter
- ft
Drum Height- ft
Vapor Velocity- ft/s
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Formula (Flare Header Pressure Drop)
ΔP = f × (L/D) × (ρ × V²) / (2 × gc)
ΔP = Pressure Drop
f = Friction Factor
L/D = Length to Diameter Ratio
ρ = Density
V = Velocity
gc = Gravitational Constant
Standards & References
API RP 521 Pressure-Relieving and Depressuring Systems
ASME B31.3 Process Piping
GPSA Engineering Data Book Gas Processors Suppliers Association
Important Notes
Flare header design must ensure acceptable pressure drop and Mach number.
Knockout drums are critical for separating liquids from vapor streams.
Vapor velocity in knockout drums should be below the flooding velocity.
Liquid holdup time in knockout drums is important for proper separation.