Simple Engineering Calculators

Frick Screw Compressor — Natural Gas Throughput

Positive-displacement screw-compressor performance estimator. Geometry from the Frick service manual 070.250-IOM1 (Table 2). Gas density via the Sutton + Dranchuk-Abou-Kassem real-gas method. Everything updates live as you change inputs.

Throughput

Standard flow
9.12MMSCFD

Million std ft³/day @ 14.696 psia, 60 °F

Mass flow
18,903lb/hr
Actual inlet flow
1,455ACFM

Real gas volume drawn in at suction

Pressure ratio
3.32: 1

Power & discharge

Estimated brake HP
603BHP
Adiabatic gas HP
561HP

Thermodynamic minimum at perfect Vᵢ match

HP per MMSCFD
66.1
Dry discharge temp
224°F

Dry adiabatic reference — oil flooding keeps the real discharge ~170–185 °F

Capacity curve

Standard flow (MMSCFD)

0.03.26.39.5136001,5752,5503,5254,500Drive speed (RPM)MMSCFD

Estimated brake HP

0.02094186278366001,5752,5503,5254,500Drive speed (RPM)Brake HP
Show the full calculation & assumptions

Machine — TDSH 233XL, swept volume 0.45580 ft³/rev

  • Displacement = swept × RPM × load = 0.45580 × 3550 × 100% = 1,618 ACFM (theoretical)
  • × volumetric efficiency 0.899 = 1,455 ACFM actually drawn in

Gas at suction (64.7 psia, 70 °F)

  • Specific gravity 0.65 → molar mass 18.83 lb/lbmol, k = 1.270
  • Compressibility Z = 0.9894 → density 0.2166 lb/ft³

Throughput

  • Mass flow = 1,455 ACFM × 0.2166 lb/ft³ × 60 min/hr = 18,903 lb/hr
  • ÷ standard density 0.04974 lb/ft³ = 6,334 SCFM = 9.12 MMSCFD

Power (built-in Vᵢ = 2.57, mech. eff 0.93)

  • Adiabatic (min) 561 HP · indicated 561 HP · brake 603 HP

Rough estimate. Volumetric efficiency is the dominant uncertainty (±5% → ±5% on flow). For a guaranteed selection, confirm against Frick CoolWare.

Read before you rely on these numbers

  • This is a rough estimate, not a guaranteed compressor selection.
  • Volumetric efficiency is the dominant assumption (±5% → ±5% on flow). Override it with a manufacturer value when you have one.
  • The discharge temperature shown is the dry adiabatic reference; oil flooding keeps the real gas discharge much lower (~170–185 °F target).
  • Geometry source: Johnson Controls–Frick service manual Form 070.250-IOM1, Table 2.