Skip to content
MaritimeTest
Log in

Fluid Hammer Effect

Mintra 5 questions

Study guide

Download PDF

Fluid hammer is the pressure surge that races through a pipe when the flow of liquid stops or starts too abruptly. It cracks pipework, wrecks fittings and contaminates cargo. This guide covers the causes, the effect and the prevention.

What it is

The fluid hammer effect is the sudden increase in pressure inside a pipe when a moving liquid is forced to stop or change speed too quickly, converting its kinetic energy into a pressure spike.

Common causes

The usual causes are rapid manual valve opening or closing and too high-speed settings on remotely operated valves. In ballast water, cargo and engine cooling systems the resulting phenomenon is a hydraulic shock.

Possible effects

Fluid hammer can cause damage to pumps, valves and filters, chemical and oil cargo contamination, and fractured pipework.

Prevention

The main defence is to change valve positions slowly, so that the liquid's velocity changes gradually. In compressed-air systems, the risk of a "slug" forming is prevented by opening the inlet valve slowly rather than snapping it open.

Key facts to remember

  • Fluid hammer = sudden pressure increase inside a pipe.
  • Causes: rapid manual valve operation; over-fast remote valve settings.
  • In ballast/cargo/cooling systems it appears as hydraulic shock.
  • Effects: damaged pumps/valves/filters, cargo contamination, fractured pipework.
  • Prevent it by opening and closing valves slowly; open a compressed-air inlet valve slowly to avoid a slug.

Compiled from the sources above and cross-checked against the official documents. Published by the MaritimeTest editorial team.

First 4 of 5 questions — with answers

The correct answer is marked. Unlock the rest to study the whole test, online or offline.

  1. Question 1

    What are common causes of fluid hammer?
    • Rapid manual valve opening or closing.
    • Too high-speed settings on remotely operated valves.
    • Overuse of swing valves.
    • Closed discharge valves.

  2. Question 2

    Which type of fluid hammer is typically encountered within ballast water, cargo and engine cooling systems?
    • Hydraulic shock.
    • Differential shock.
    • Thermal shock.
    • Piston shock.

  3. Question 3

    How can you prevent the risk of a slug forming in compressed air systems?
    • Open the inlet valve slowly.
    • Open the inlet valve quickly.

  4. Question 4

    What is the fluid hammer effect?
    • The sudden increase in pressure inside a pipe.
    • The sudden decrease in pressure inside a pipe.
    • The use of high-pressured water to clean inside a pipe.
    • The use of high-pressure steam to clean inside a pipe.

Preview — 4 of 5 questions

You are seeing the first 4 questions with answers. Unlock the remaining 1 to study the whole test — online or offline.

Related Mintra tests