Flare Disposal Calculator | Header & KO Drum

Calculation Mode:

Header Pressure Drop Header Sizing Knockout Drum

Gas Properties & Flow

Mass Flow Rate

lb/hr

Gas Specific Gravity

(air=1)

Operating Temperature

°F

Operating Pressure

psig

Liquid Mass Fraction

Header Parameters

Header Diameter (ID)

Header Length

Pipe Roughness

Maximum Mach Number

📚 Learn the Theory

Comprehensive guide to flare system design, API RP 521 methodology, and knockout drum sizing principles.

Read Engineering Guide →

Formulas

Header Pressure Drop (Darcy-Weisbach)

ΔP = f × (L/D) × (ρ × V²) / (2 × g_c)

KO Drum Velocity (Souders-Brown)

V_max = K × √[(ρ_L - ρ_G) / ρ_G]

Standards & References

API RP 521
Pressure-Relieving and Depressuring Systems (7th Ed.)
GPSA
ASME B31.3
Process Piping

Design Guidelines

Mach ≤ 0.5: Recommended for flare headers per API RP 521 to prevent acoustic fatigue and excessive backpressure.
Mach ≤ 0.7: Maximum allowable for flare headers; avoid sustained operation above this limit.
KO Drum K-values: Range 0.10-0.35 depending on service. Lower K for foaming/dirty service.
Retention time: Typically 10-20 minutes for knockout drums to ensure proper liquid separation.
H/D Ratio: Typical 2-4 for vertical knockout drums; higher ratios improve vapor-liquid separation.

Frequently Asked Questions

What does the Flare Disposal Calculator size?

It sizes flare headers and knockout drums per API RP 521 and GPSA, calculating pressure drop, Mach number, vapor velocity, and liquid holdup.

What is a knockout drum in a flare system?

A knockout drum separates and collects liquid from the gas stream before it reaches the flare tip, preventing liquid carryover.

What standards does this flare disposal tool follow?

The calculator follows API RP 521 and GPSA standards for flare disposal system design.

Flare Disposal System Sizing Calculator

Gas Properties & Flow

Header Parameters

Knockout Drum Parameters

📚 Learn the Theory

Pressure Drop Results

Header Sizing Results

KO Drum Sizing Results

Formulas

Standards & References

Design Guidelines

Frequently Asked Questions

Flare Disposal System Sizing Calculator

Gas Properties & Flow

Header Parameters

Knockout Drum Parameters

📚 Learn the Theory

Pressure Drop Results

Header Sizing Results

KO Drum Sizing Results

Formulas

Standards & References

Design Guidelines

Frequently Asked Questions

Related Calculators

Flare Backpressure

Flare Radiation

PSV Header Sizing

Relief Valve Sizing