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Filter Separator Calculator

Per API RP 52 & GPSA

Coalescing Filter Separator Sizing
Size two-stage filter separators for fuel gas conditioning, custody transfer, and high-efficiency liquid/solid removal. Calculates element count, vessel dimensions, pressure drop, and separation efficiency per API RP 52 and GPSA Section 7.

Service Conditions

Determines element type and efficiency requirements
At standard conditions (60°F, 14.7 psia)
psig
°F

Gas Properties

Air=1.0
Natural gas: 0.55-0.80 typical
cP
At operating temperature
-
Leave blank to estimate
gal/MMSCF
Typical: 0.5-5 gal/MMSCF

Design Parameters

Affects capacity and efficiency
psi
Typically 1-3 psi when new
psi
Element changeout threshold: 5-15 psi
%
Safety factor on element count

Filter Separator Design

Element Capacity:

Qelement = Aface × Vface

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

Pressure Drop (Clean):

ΔP = K × (ρ × V²) / 2gc

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