Wastewater New York State Practice Exam

Which characteristic is true of a diaphragm pump?

1. Utilizes a motor coupled directly to the pump

2. Relies on rollers to push the fluid

3. Uses a membrane to fill a chamber

4. Requires external compressed air to operate

The correct answer is: Uses a membrane to fill a chamber

A diaphragm pump operates based on a mechanism that involves a flexible membrane or diaphragm which moves back and forth to create a vacuum that draws fluid into a chamber. When the diaphragm moves in one direction, it increases the volume of the chamber, allowing for fluid to be pulled in. When it moves in the opposite direction, it decreases the volume of the chamber, thereby pushing the fluid out of the pump. This design allows diaphragm pumps to handle a variety of fluids, including those that may be sensitive to shear stress, making them suitable for applications where maintaining fluid integrity is crucial. In contrast, the other options lack the fundamental characteristics of diaphragm pumps. For instance, some pumps utilize direct motor coupling or rollers, which describe totally different types of pumping mechanisms, such as gear pumps or peristaltic pumps. Additionally, while some pumps may operate using external compressed air, this is characteristic of pneumatic diaphragm pumps instead of the traditional diaphragm design that inherently uses its membrane mechanism for operation.