What are flow control devices primarily used for in a collection system?

Flow control devices are primarily used in collection systems to regulate flow and prevent system overloads. This is crucial for maintaining the operational integrity of the wastewater collection system. By controlling the rate of flow, these devices ensure that the system does not exceed its capacity, which could lead to backups, overflows, or other malfunctions. This regulation also helps to manage the fluctuations in inflow that might occur due to varying rainfall or other regional influences, ensuring that the treatment plants operate efficiently and within their designed limits.

The other options, while relevant to different aspects of wastewater management, do not accurately describe the primary function of flow control devices in the context of a collection system. For example, increasing flow velocity is not the main goal of these devices, nor are they specifically designed for measuring wastewater volume or mixing chemicals, which are handled by different systems and components within the wastewater treatment process.