⚡ Check Valve Slam & Air Chamber

Calculate reverse velocity slam pressure spikes during pump trip and size pneumatic air cushion surge vessel dampening.

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

Fluid Mechanics

📊 Solver Telemetry ● ACTIVE

👁️ Views 37

⚡ Solves 31

💾 Downloads 488 📦 Fortran Code 4.4 KB

📅 Released Jun 2026

⏱️ Latency < 1 ms

💡 Hardware & Sizing Partner: Need to size a control valve or check ASME flange bolt torque for this line?

FLOWKS IEC 60534 Sizer ↗ • API 6D Valve Catalog →

⚡ Check Valve Dynamic Closure & Air Vessel Surge Dampening

Real-time visual simulation of reverse flow slam and pneumatic buffer compression

📝 Configuration & Presets

💧 Water Station (400 mm) 🪨 Slurry Line (250 mm) 🏢 High-Rise Booster (100 mm) 🛢️ Reflux Pump (150 mm)

📐 Pipeline & Acoustic Parameters

Pipe Diameter D [mm]:

Pipeline Length L [m]:

Initial Flow Velocity v₀ [m/s]:

Acoustic Wave Speed a [m/s]: Water in steel: 1000–1200 m/s, Plastic: 300–500 m/s

⚡ Pump Trip Deceleration & Valve Type

Flow Deceleration Rate dv/dt [m/s²]: Typical pump trip: 2 to 15 m/s²

Check Valve Design Type:

🛡️ Pressure Limits & Air Vessel Protection

Static Pipeline Pressure [bar gauge]:

Allowable Surge Rise ΔP_allow [bar]:

Key Dynamic Formulations:
• Reverse Velocity: v_R = (dv/dt) · t_close
• Joukowsky Slam: ΔP_slam = ρ · a · v_R
• Peak Pressure: P_peak = P_static + ΔP_slam
• Air Vessel: V_air = [2 A L v₀² ρ] / [2 · 10⁵ · ΔP_allow (1 + P_stat/ΔP_allow)]

📊 Slam & Vessel Sizing Results

📊 Output Summary
💾 Fortran Source

Valve Slam Risk Assessment

🚨 HIGH SLAM & BURST HAZARD

Selected Valve: Standard Swing Check (Slow Response) (t_close ≈ 0.350 s)

Slam Surge Pressure Spike +17.29 bar Peak = 25.29 bar

Recommended Air Chamber 662 Liters 0.66 m³ cushion

Max Reverse Velocity (v_R) 1.575 m/s dv/dt = 4.5 m/s²

Acoustic Wave Speed (a) 1100 m/s Pipe Length = 1200 m

📈 Slam Pressure Spike vs Deceleration dv/dt

📉 Required Air Cushion Volume vs Allowable ΔP

=================================================================
 THERMOFLUIDCALC — CHECK VALVE SLAM & AIR CHAMBER SIZING REPORT
=================================================================
Case Title                 : Municipal Water Transmission Pumping Station Trip
Pipe Diameter (D)          : 400.0 mm (0.4000 m)
Pipeline Length (L)        : 1200.0 m
Initial Flow Velocity (v0) : 2.20 m/s
Fluid Deceleration (dv/dt) : 4.50 m/s2
Check Valve Type           : Standard Swing Check (Slow Response)
Valve Dynamic Action Time  : 0.350 s
-----------------------------------------------------------------
Maximum Reverse Velocity   : 1.5750 m/s
Joukowsky Slam Surge Spike : 17.29 bar (1729.04 kPa)
Total Peak Pipe Pressure   : 25.29 bar (2529.03 kPa)
Allowable Surge Limit      : 3.00 bar
Recommended Air Cushion    : 662.2 Liters (0.662 m3)
=================================================================

📘 Calculation Methodology & Engineering Theory

Dynamic Reverse Flow & Valve Slam

When a pump trips, fluid decelerates at rate $dv/dt$. Check valves take finite time $\Delta t_c$ to seat, allowing reverse flow to develop:

                    vR = (dv/dt) · tclose,    ΔPslam = ρ · a · vR
                

Fast-acting nozzle non-slam check valves close before significant reverse velocity builds up.

Air Cushion Vessel Sizing

Pneumatic air chambers absorb kinetic energy of the reversing fluid column through polytropic air compression, limiting peak head to $\Delta P_{allow}$.

Key Engineering Assumptions

Rigid or elastic pipe acoustic wave speed calculated via Korteweg equation.
Uniform fluid column deceleration after pump power trip.
Isothermal / polytropic gas compression ($n = 1.2$) inside the air vessel.

ThermoFluidCalc Engineering Report