Which type of flowmeter is NOT commonly used in fire apparatus engineering?

The type of flowmeter that is not commonly used in fire apparatus engineering is a laser flowmeter. Fire apparatus engineering typically requires flowmeters that are rugged, reliable, and designed to operate in the high-pressure and variable flow conditions often encountered during firefighting operations.

Differential, turbine, and paddlewheel flowmeters are all commonly used in this field because they can accurately measure the flow of water and other liquids under the conditions present in firefighting scenarios. These types of flowmeters have been proven over time to provide reliable measurements, which is critical for ensuring that fire systems operate effectively and safely.

In contrast, while laser flowmeters can be very accurate in specific applications, they are generally used in more specialized industrial contexts where precise measurements of low flow rates or very specific fluid characteristics are needed. Their complexity, cost, and the requirement for specific conditions for operation make them less practical for general firefighting instrumentation compared to the three other options listed.