Pump Check Valve Slam & Reverse Velocity Calculator

Estimate reverse flow velocity (vR) prior to disc seating, fluid deceleration (dv/dt), and sudden Joukowsky slam pressure spike per Thorley & Provoost.

Pump Trip & Check Valve Dynamics

Check Valve Design Type:

Pipeline Deceleration dv/dt (m/s²): Typical: 2 - 10 m/s² following sudden pump trip

Acoustic Wave Speed a (m/s):

Liquid Density ρ (kg/m³):

Initial Forward Velocity v₀ (m/s):

Operating Static Head H₀ (bar):

Check Valve Slam & Shockwave

Max Reverse Velocity v_R:

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Slam Pressure Spike ΔP:

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Total Peak Pressure P_tot:

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Dynamic Closure Lag Δt:

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Check Valve Slam Severity:

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Frequently Asked Questions

What is check valve slam in a pumping station?

When a pump trips, liquid decelerates and reverses direction toward the pump. If the check valve disc cannot close before reverse flow develops, the reversing liquid column slams the disc shut against its seat, generating an intense acoustic pressure spike.

Why do nozzle check valves prevent valve slam?

Nozzle (axial) check valves feature a light disc, strong closing spring, and extremely short travel distance (e.g., 20% of pipe diameter). The disc seats almost instantaneously at the exact moment forward velocity hits zero.

How does pipeline deceleration rate (dv/dt) influence valve slam?

Systems with high static lift and short pipes experience violent deceleration (dv/dt > 5–15 m/s²). The faster the column decelerates, the deeper the reverse flow penetrates before slow check valves can seat.