Ontario Operator-in-Training (OIT) Practice Exam

What distinguishes static pressure from dynamic pressure?

1. Static pressure is higher in flowing conditions

2. Dynamic pressure occurs in non-moving water

3. Static pressure involves water that isn't moving

4. Dynamic pressure exists in stagnant water

The correct answer is: Static pressure involves water that isn't moving

Static pressure is defined as the pressure exerted by a fluid at rest. It represents the energy per unit volume available from the fluid at a given point and is independent of the fluid's motion. This is why the third choice is the correct answer—static pressure pertains to water or any fluid that is not in motion, allowing for an accurate measurement of pressure at a specific point in a system. Dynamic pressure, on the other hand, is associated with the movement of fluids. It arises from the fluid’s velocity and can be calculated as the kinetic energy per volume of the fluid flow. In systems where water is flowing, dynamic pressure is significant and is responsible for the kinetic energy of the moving fluid. In contrast, the other statements are not accurate in their definitions. Saying that static pressure is higher in flowing conditions does not capture the essence of static pressure as it is independent of flow. Also, dynamic pressure is not exclusive to stagnant water; rather, it is absent when there is no movement. Understanding these distinctions is essential for operators in water treatment and distribution systems.