Basic Wastewater Operator Practice Exam

If you have a lime slurry feed line, what is the best valve to use?

1. Plug valve

2. Butterfly valve

3. RPZ dual check valve

4. Gate valve

The correct answer is: Plug valve

In situations involving a lime slurry feed line, the best valve choice is a plug valve. This type of valve is particularly effective for handling slurries due to its design, which allows for a smoother flow of viscous materials and reduces the likelihood of clogging. The straight-through flow path of a plug valve minimizes turbulence, consequently preventing the buildup of solids that could occur with other valve types that may have more complex flow patterns. Additionally, plug valves are easy to operate and maintain, making them a practical choice for lime slurry applications where consistent flow control is necessary. They provide excellent sealing characteristics, which is crucial in preventing leaks, especially when dealing with caustic materials such as lime. In contrast, butterfly valves can sometimes create turbulence and are typically more suited for less viscous fluids. Gate valves, while effective for on/off control, do not perform well with slurries and can cause sediment buildup. Lastly, an RPZ dual check valve is specifically designed for backflow prevention and does not serve the functional needs required for managing slurry flow effectively.