Red Seal Instrumentation and Control Technician Practice Exam

How does a flow switch operate?

1. It measures the temperature of flowing fluids

2. It controls the speed of a pump

3. It detects fluid flow and activates alarms or controls

4. It regulates the pressure in pipelines

The correct answer is: It detects fluid flow and activates alarms or controls

A flow switch operates by detecting the movement of fluid within a pipe or conduit and subsequently activating alarms or control mechanisms based on that detection. When the flow of fluid reaches a certain threshold, the flow switch's internal mechanism, often utilizing a float, paddle, or turbine, signals that an acceptable flow condition has been met. This enables the system to respond appropriately, such as by sounding alarms if flow falls below critical levels or engaging control actions to maintain process stability. The other options describe functions that do not align with the primary purpose of a flow switch. Measuring the temperature of flowing fluids pertains to temperature sensors, while controlling the speed of a pump is typically managed by variable frequency drives or controllers rather than a flow switch. Lastly, regulating pressure in pipelines is generally the role of pressure regulators or control valves. Hence, the function of a flow switch is uniquely focused on monitoring and reacting to the flow of fluid.