Ontario Operator-in-Training (OIT) Practice Exam

Which meter can be used in a closed pipe system?

1. Orifice meters

2. Velocity meters only

3. Surface water meters only

4. Gravity flow meters only

The correct answer is: Orifice meters

Orifice meters are designed to measure flow rates in closed pipe systems. They operate by creating a pressure drop across an orifice plate inserted into the flow stream. This pressure drop is proportional to the flow rate, allowing for the calculation of the velocity of the fluid passing through the orifice. Since orifice meters are specifically built to function in environments where the flow is confined within a pipe, they are particularly well-suited for closed systems. In contrast, velocity meters may not be used exclusively in closed systems, as they can also measure flow in open channels under certain conditions. Surface water meters are typically used in open water sources, making them unsuitable for closed pipe systems. Gravity flow meters are associated more with open systems where the flow is driven by gravitational forces rather than pressurized systems. Overall, orifice meters' unique design and function make them ideal for accurately measuring flow in closed pipe systems, showcasing their essential role in various industrial and municipal applications.