What is one drawback of a piston positive displacement pump?

• A. The pump is less efficient
• B. The fire stream tends to pulsate
• C. It requires more maintenance
• D. The pump cannot handle viscous liquids

Answer: (B)

A piston positive displacement pump operates by using a piston to move fluid through a chamber, which creates a specific volume of fluid displacement. One notable characteristic of this type of pump is that the fluid is moved in a series of discrete volumes, rather than in a continuous flow. This mechanism inherently leads to variations in the flow, resulting in a fire stream that can pulsate.

This pulsation can be significant during operation, causing challenges in applications where a steady and smooth flow of fluid is critical—like in firefighting situations where consistent pressure is necessary to effectively deliver water. Therefore, this characteristic of the piston pump is pertinent and represents a considerable drawback in scenarios where the steadiness of the stream is paramount.

While other aspects like efficiency, maintenance needs, and viscosity handling are important, the pulsating nature of the output is a specific operational concern for piston positive displacement pumps that can directly impact their effectiveness in certain applications.