Filter Separator Calculator

Service Conditions

Service Type Determines element type and efficiency requirements

Gas Flow Rate

At standard conditions (60°F, 14.7 psia)

Operating Pressure

psig

Operating Temperature

°F

Gas Properties

Gas Specific Gravity

Air=1.0

Natural gas: 0.55-0.80 typical

Gas Viscosity

At operating temperature

Compressibility Factor (Z)

Leave blank to estimate

Inlet Liquid Loading

gal/MMSCF

Typical: 0.5-5 gal/MMSCF

Design Parameters

Element Type Affects capacity and efficiency

Efficiency Target

Max Pressure Drop (Clean)

psi

Typically 1-3 psi when new

Max Pressure Drop (Dirty)

psi

Element changeout threshold: 5-15 psi

Design Margin

Safety factor on element count

📚 Learn the Theory

Understand coalescing filter design, element sizing, two-stage separation, and efficiency calculations

Read Engineering Guide →

Filter Separator Design

Element Capacity:

Q_element = A_face × V_face

Face velocity typically 40-80 ft/min for coalescing elements

Pressure Drop (Clean):

ΔP = K × (ρ × V²) / 2g_c

Typical Element Capacities (ACFM/element):
• 6" × 36" Fiberglass: 80-120 ACFM
• 6" × 48" Fiberglass: 100-150 ACFM
• Pleated cartridge: 150-300 ACFM

Service Requirements:
• Fuel gas: ≤0.1 gal/MMSCF outlet
• Instrument gas: ≤0.01 gal/MMSCF outlet
• Custody transfer: Per contract spec

Sizing Results

Vessel Size

Vessel Diameter: -

Vessel Length: -

Shell Thickness: -

First Stage (Coalescing)

Element Count: -

Element Size: -

Face Velocity: -

Second Stage (Separator)

Separator Type: -

Velocity Check: -

Performance

ΔP Clean: -

ΔP @ Changeout: -

Outlet Quality: -

Efficiency: -

Vessel Schematic

Reference Drawing

Filter Separator General Arrangement Drawing

Nozzle designations correspond to nozzle schedule

Frequently Asked Questions

What does the filter separator calculator size?

It sizes coalescing filter separators for fuel gas conditioning and custody transfer, including two-stage element sizing, pressure drop, and efficiency calculations.

What standards does this calculator follow?

Calculations follow API RP 52 and GPSA standards for coalescing filter separator design.

Is this filter separator calculator free to use?

Yes, the calculator is free to use online with no signup required.