Water Treatment Operator-in-Training (OIT) Practice Test

How is water pressurized in a positive displacement pump?

1. By changing the temperature

2. By the weight of the water

3. By a screw, piston, gear or diaphragm

4. By gravity force

The correct answer is: By a screw, piston, gear or diaphragm

The pressurization of water in a positive displacement pump occurs through the mechanical action of components such as a screw, piston, gear, or diaphragm. These elements work by physically displacing a fixed volume of water within the pump's chamber to create pressure. As the pump operates, the moving parts compress the water, which forces it out of the pump at a higher pressure than it entered. This mechanism is intrinsic to positive displacement pumps and differs from other types of pumps that may rely on kinetic energy or movement patterns like centrifugal force. In positive displacement pumps, the design ensures that water is moved in a controlled manner, providing a consistent flow regardless of the downstream pressure changes. As a result, this approach is highly effective for applications requiring a reliable and steady output of liquid.