Why must the velocity in pipe be controlled?

Controlling the velocity in pipes is crucial primarily to avoid breaking materials like PVC pipes. PVC is a popular choice in landscaping and irrigation due to its lightweight and corrosion-resistant properties; however, it has a lower tolerance for stress compared to other materials. Excessive velocity can lead to significant pressure surges or water hammer effects, which can cause vibrations and ultimately result in cracks or failure of the pipe.

When the velocity of water flow is too high, it can create turbulence, adding to stress on the pipe walls. Therefore, regulating the flow velocity ensures that the integrity of the pipe is maintained, preventing damage and costly repairs.

While other options mention important aspects such as accommodating temperature changes or influencing pipe lifespan, the immediate priority regarding pipe integrity in landscaping applications is to manage the velocity to protect the material used.