Gas Compressor Sizing
Calculate compressor horsepower and staging requirements
Input Parameters
Enter gas flow and pressure conditions
Compressor Selection Guide
- Reciprocating: 0.1-100 MMSCFD, high ratio (up to 10:1/stage)
- Centrifugal: 10-500+ MMSCFD, high efficiency at design point
- Rotary Screw: 0.5-50 MMSCFD, low maintenance
Compressor Results
Enter parameters and click Calculate
Formula Reference
Compression Ratio
Overall Ratio:
R = P2 / P1 (absolute pressures)
Stage Ratio (optimal):
r = R^(1/n) where n = number of stages
Max single stage ratio:
Reciprocating: 3-4 (up to 6 for special designs)
Centrifugal: 2-3 per wheel
Screw: 4-6
Adiabatic Head
Adiabatic Head (ft-lbf/lbm):
Had = (Z_avg * R_gas * T1 * k) / (MW * (k-1)) * [(r^((k-1)/k)) - 1]
Where:
Z_avg = Average compressibility
R_gas = 1545.35 ft-lbf/(lbmol-R)
T1 = Suction temperature (R)
k = Specific heat ratio (Cp/Cv)
MW = Molecular weight
r = Compression ratio
Horsepower Calculation
Gas Horsepower:
GHP = (m_dot * Had) / 33000
Where:
m_dot = Mass flow rate (lb/min)
Had = Adiabatic head (ft-lbf/lbm)
33000 = ft-lbf/min per HP
Brake Horsepower:
BHP = GHP / (eta_p * eta_m)
Where:
eta_p = Polytropic efficiency (0.75-0.85)
eta_m = Mechanical efficiency (0.95-0.98)
Discharge Temperature
Adiabatic Discharge Temperature:
T2 = T1 * r^((k-1)/k)
Actual Discharge Temperature:
T2_actual = T1 * r^((k-1)/(k*eta_p))
Temperature Rise:
dT = T2_actual - T1