Modern industrial processes depend heavily upon automated fluid control. The routing and flow rates for fluids within a plant environment are under the direction of computerized controllers, and this has proven to be a precise, reliable system. However, the physical laws behind fluids in motion aren't altered by any amount of electronic sophistication; that means changes in fluid dynamics are predictably going to affect systems.
One such effect is known as water hammer, and it can be destructive to equipment and processes. Below is more information about water hammer and what you can do to prevent it from occurring:
What is water hammer and why is it bad?
Water hammer occurs when a fluid within a system transitions from either:
Flowing to non-flowing
Non-flowing to flowing
In addition, this transition creates a shock to pipes, valves and other fluid control components for it to be considered water hammer. The name of this phenomenon is in reference to the loud sound made by the acoustic impact of the shock.
Water hammer is not a harmless reaction to flow transition; instead, it is capable of causing real damage to the fluid infrastructure. Water hammer can blow-out valves, burst pipes, and push-out seals. Even if the damage isn't acute, the cumulative effects from water hammer will lead to premature failure of components.
What are the causes of water hammer?
Water hammer can be caused by numerable things; some of the most common include:
Quick opening or closing of valves
Check valve backflow
Equipment and power failures
Rapid pump startup or stopping
The good news is that most of the above items can be prevented by astute managers of fluid process control. However, water hammer isn't going to self-correct, and, in fact, it must be addressed ahead of time to avoid its damaging effects.
How can water hammer be prevented?
Engineers and other technical designers and managers have several methods at their disposal in the battle against water hammer. Below are several of these that can successfully prevent it from happening:
Install surge tanks – these devices consist of a tank that is mounted inline to a pipe. The principles governing a surge tank's use and operation are simple, as it serves to absorb the "blow" of water hammer by filling with an oncoming rush of fluids. The tanks contain a flexible inner bladder that expands and contracts depending upon system inputs.
Use slow opening and slow closing valves – these valves are capable of being opened and closed at low speeds; this prevents water from developing the momentum necessary to cause water hammer. Keep in mind that special valves also may require additional programmable controllers that are able to handle them.
Reduce or eliminate back flow of fluids into check valves – check valves serve a valuable purpose by preventing harmful reverse flowing of fluids. These valves are particularly suspect to water hammer if the back flowing fluids are permitted to freely run into the valve. Reducing back flow of fluids may require restructuring of pipes, such as eliminating uphill runs on the exit side of the valve.
Reduce the length of straight pipe – as pipes lengthen, the buildup of energy from the water hammer's precipitating event also increases. Reducing straight line lengths of pipe prevents this buildup from occurring. This can be accomplished by adding elbow fittings to interrupt the straight-line flow of fluids.
Adjusting or replacing programmable controllers – closely related to changing valves, it may be that making adjustments to the speeds of valve opening and closing are sufficient to thwart water hammer. Utilizing the skills of computer programmers can help make necessary coding revisions a simpler task. However, some controllers may be incapable of being fine-tuned to the degree needed, and that will require new investments in equipment.
Check out companies like DEWCO Pumps & Equipment, Inc for more information.