🌀 Centrifugal Pump NPSH Available & Cavitation Sizer

Calculate centrifugal pump NPSH available (NPSHa), cavitation safety margin (NPSHa - NPSHr), vapor pressure, suction pipe friction losses, and Thoma cavitation parameter.

⚡ Fortran 90 Engine Double Precision (IEEE 754) ✓ ISO / ASME Validated

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👁️ Consultations 35

⚡ Calculs faits 28

💾 Téléchargements 133 📦 Code Fortran 4.5 KB

📅 Mise en service Jun 2026

⏱️ Latence < 1 ms

🌀 Centrifugal Pump Suction Hydraulics & Impeller Eye Cavitation Zone

Real-time visual simulation: Suction tank liquid level, line losses, and vapor bubble collapse in impeller eye

📝 Configuration & Presets

💧 Flooded Suction Water (Safe) ⚠️ River Suction Lift (-4m) 🔥 Boiler Feed Deaerator (130°C) ⛽ Volatile Gasoline Solvent

🧪 Fluid Selection & Vessel State

Pumping Fluid Medium:

Vessel / Atm Pressure P₀ [bar abs]:

Fluid Temperature [°C]:

📏 Suction Piping & Static Level

Static Suction Head z_s [m]: + Flooded, - Suction Lift

Pumping Flow Rate Q [m³/h]:

Suction Pipe ID D [mm]:

Suction Pipe Length L [m]:

Sum of Minor Loss Coefficients ∑K: Elbows, valves, strainer, inlet

⚙️ Pump Required Performance

Pump Required NPSH_r [m]: From pump manufacturer curve (3% head drop)

Pump Total Head H [m]:

Hydraulic Institute (HI 9.6.1) NPSH Formulation:
• NPSH Available: NPSH_a = (P_vessel − P_v(T)) / (ρ g) + z_s − h_loss [m]
• Cavitation Margin: ΔNPSH = NPSH_a − NPSH_r ≥ 0.6 m (or CMR ≥ 1.2 - 1.5)
• Thoma Cavitation Number: σ = NPSH_a / H_pump
• Velocity Limit: Suction velocity V should remain between 1.0 - 2.5 m/s.

📊 NPSH & Cavitation Results

📊 Output Summary
💾 Fortran Source

Net Positive Suction Head Available (NPSH_a)

4.89 meters

NPSH_r: 4.00 m | Margin: +0.89 m (CMR = 1.22)

ACCEPTABLE (HI MARGIN)

Cavitation Safety Margin +0.89 m HI Target: ≥ +0.60 m

Suction Line Flow Velocity 2.83 m/s Recommended: 1.0 - 2.5 m/s

Fluid Vapor Pressure P_v 271.78 kPa At 130 °C

Suction Piping Head Loss 0.99 m Friction + Minor losses

📈 NPSHa & NPSHr (m) vs Flow Rate Q (m³/h)

📉 NPSHa (m) vs Fluid Temperature T (°C)

=================================================================
 THERMOFLUIDCALC — PUMP NPSHa & CAVITATION ANALYSIS REPORT
=================================================================
Case Title                 : Power Plant Boiler Feed Pump from Deaerator
Fluid Medium               : Hot Boiler Feed Water (Deaerator)
Operating State            : P_vessel = 2.800 bar abs, Temp = 130.0 C (Vapor Press Pv = 271.784 kPa)
Suction Line Geometry      : ID = 150.0 mm, Length = 6.0 m, sum K = 1.8, Static Head zs = +5.00 m
Flow & Velocity            : Q = 180.00 m3/h (50.00 L/s), Suction Velocity V = 2.83 m/s
-----------------------------------------------------------------
NPSH AVAILABLE (NPSHa)     : 4.894 meters (44.888 kPa)
NPSH REQUIRED (NPSHr)      : 4.000 meters (3% Head Drop Curve)
CAVITATION SAFETY MARGIN   : +0.894 meters (NPSHa - NPSHr)
Cavitation Margin Ratio    : 1.223 (NPSHa / NPSHr)
Thoma Cavitation Number    : 0.0576 (NPSHa / H_pump = 85.0 m)
Total Suction Head Losses  : 0.986 meters (Friction + Minor)
CAVITATION RISK STATUS     : ACCEPTABLE (HI MARGIN)
=================================================================

📘 Calculation Methodology & Hydraulic Institute Standards

Hydraulic Institute NPSH Margin (HI 9.6.1)

NPSH margin is the difference between $NPSH_a$ and $NPSH_r$. A margin of at least $0.6 - 1.5\,\text{m}$ (or $CMR \ge 1.3$) prevents vapor cavity collapse, impeller pitting erosion, and high-frequency vibration.

Vapor Pressure & Temperature Impact

As fluid temperature rises, vapor pressure $P_v(T)$ increases exponentially according to the Antoine equation, reducing $NPSH_a$ dramatically and demanding higher suction elevation or pressurization.

Key Engineering Assumptions

Swamee-Jain / Darcy-Weisbach pipe friction model.
Sum of minor losses $\sum K$ includes strainer, foot valve, elbows, and reducer.
Applicable to water supply, chemical transfer, hydrocarbon pumps, and boiler feed deaerators.

ThermoFluidCalc Engineering Report