NOTES ON WATER HAMMER
What is WATER HAMMER?
Water hammer is a pressure wave or surge, as well as a temporary rise in pressure or
hydraulic shock, created by the kinetic energy of a non viscous fluid in motion when it is
abruptly stopped or changed direction.
When a moving mass of liquid comes to a halt or changes direction abruptly, its kinetic
energy is converted into pressure energy.
Pump system start-up or shut down that is slow or abrupt, pipe breakage, turbine
failure, or electric power interruption to a pump's motor are all instances. Surge is a
slow-moving water mass oscillation generated by system internal pressure changes.
Water hammer occurs when a steam system is turned on or energized. Water hammer
can occur if the steam line is powered too soon without adequate warm-up time and
the condensate formed during startup is not properly removed.
Pressure energy is delivered to the valve and pipe wall when a swiftly closed valve
abruptly stops water flowing in a pipeline. Within the system, shock waves are created.
Pressure waves travel backwards until they hit the next solid obstruction, then ahead,
backwards, and forward again. The pressure wave's velocity is equal to the speed of
sound. It causes harmful noise as it goes back and forth until frictional losses dissipate it.
Consecutive pressure wave reflections between the pipe inlet and the closed valve,
resulting in alternating pressure increases and drops, frequently cause severe
mechanical damage.
Depending on valve size and system conditions, a valve closing in 1.5 seconds or less
creates an abrupt stopping of flow.
When a valve closes quickly, the pressure spike (acoustic wave) can be as high as five
times the system working pressure.
Pressure waves can be caused by incorrect flow direction through valves, especially as
the valve functions.
For steel tubes, the pressure wave or spike can travel at speeds reaching 1400 m/s.
Damaged pressure variations are caused by rapid changes in flow, the operation of
positive displacement pumps, entrained or separated gases, and high temperatures.
When a vapor bubble breaks, as in cavitations, water rushes into the space from all
sides, resulting in hammer.
What is WATER HAMMER?
Water hammer is a pressure wave or surge, as well as a temporary rise in pressure or
hydraulic shock, created by the kinetic energy of a non viscous fluid in motion when it is
abruptly stopped or changed direction.
When a moving mass of liquid comes to a halt or changes direction abruptly, its kinetic
energy is converted into pressure energy.
Pump system start-up or shut down that is slow or abrupt, pipe breakage, turbine
failure, or electric power interruption to a pump's motor are all instances. Surge is a
slow-moving water mass oscillation generated by system internal pressure changes.
Water hammer occurs when a steam system is turned on or energized. Water hammer
can occur if the steam line is powered too soon without adequate warm-up time and
the condensate formed during startup is not properly removed.
Pressure energy is delivered to the valve and pipe wall when a swiftly closed valve
abruptly stops water flowing in a pipeline. Within the system, shock waves are created.
Pressure waves travel backwards until they hit the next solid obstruction, then ahead,
backwards, and forward again. The pressure wave's velocity is equal to the speed of
sound. It causes harmful noise as it goes back and forth until frictional losses dissipate it.
Consecutive pressure wave reflections between the pipe inlet and the closed valve,
resulting in alternating pressure increases and drops, frequently cause severe
mechanical damage.
Depending on valve size and system conditions, a valve closing in 1.5 seconds or less
creates an abrupt stopping of flow.
When a valve closes quickly, the pressure spike (acoustic wave) can be as high as five
times the system working pressure.
Pressure waves can be caused by incorrect flow direction through valves, especially as
the valve functions.
For steel tubes, the pressure wave or spike can travel at speeds reaching 1400 m/s.
Damaged pressure variations are caused by rapid changes in flow, the operation of
positive displacement pumps, entrained or separated gases, and high temperatures.
When a vapor bubble breaks, as in cavitations, water rushes into the space from all
sides, resulting in hammer.
