1. Water Hammer

2. Where Water Hammer Occurs
In any water supply line, hot or cold
Will be more pronounced in biphase* systems
Examples of biphase applications are heat exchangers, tracer lines, steam mains, condensate return lines, and pump discharge lines
*Systems that carry water in two states, as a liquid and as a gas

3. Damaging Effects of Water Hammer
Thermostatic Elements
Overstress Gauges
Crack Trap Bodies
Rupture Fittings
Collapse Floats
Over time repeated stress on the pipe will weaken to the point of rupture

4. Conditions causing water hammer
Hydraulic Shock
Thermal Shock
Differential Shock

5. Visualize what happens at home when a faucet is open
Hydraulic Shock
Visualize what happens at home when a faucet is open
100 Pounds of Water
Moving 10 feet per second
Equaling 7 miles per hour
Shut Suddenly…. Equaling
100 Pound Hammer Stopping
“Bang” “Bang” “Bang”
600 psi Shock Wave
Reflecting Back to Forth until energy is dissipated

6. Thermal Shock This Kind of Shock is Temperature Related
Flash Steam Bubbles become Trapped in Pools of Condensate
Flooded Main, Tracer Line, Heat Exchanger Tubing or Pumped Condensate Return
Condensate will be below saturation causing immediately collapse
1 pound of steam equals 1,600 times volume of water
Causing a vacuum in all directions

7. Differential Shock Steam flowing over condensate can create waves
Velocity of Steam is times greater than the velocity of liquid
Steam moving over the condensate will start manufacturing waves
Waves will grow until they block the pipe completely forming a “Slug”
Steam cannot flow through the sealed condensate wall, thus causing positive to negative pressure zone from the back to front of the “Slug”
Stopping only when suddenly impacted by equipment, tee, elbow, valve, or any bend in the piping