Where quick closing valves are used on water lines what must also be installed to protect them?

Quick closing valves can create significant water hammer effects due to the sudden disruption in water flow. When these valves close rapidly, the momentum of the water can generate pressure surges that lead to vibrations and potential damage in the piping system. To mitigate this impact, a hammer arrestor must be installed.

A hammer arrestor acts as a cushion that absorbs the shock waves generated by the sudden change in water flow. It typically contains a sealed air chamber that compresses and expands in response to the water pressure surges, thereby reducing the harmful effects associated with water hammer. This device is crucial for maintaining the integrity of the plumbing system and ensuring the longevity of the piping and fixtures.

While the other options may relate to aspects of plumbing systems—for example, an air chamber also provides some level of dampening, but it is less effective than a properly designed hammer arrestor in this context. A check valve prevents backflow, and a pressure regulator controls the pressure in the system, neither of which address the specific issue of water hammer effectively. Thus, the requirement for a hammer arrestor when quick closing valves are present is essential for safeguarding the plumbing system against damaging pressure surges.