Which standpipe system requires manual operation of a control valve to access water?

The correct answer is a dry standpipe with a manual control valve. In this system, the valve must be operated manually to allow water to flow through the standpipe. This design is essential in scenarios where the standpipe may need to be charged with water from a fire department connection during an emergency. The operator is required to physically control the valve to open or close it, making it integral for accessing the water supply in non-pressurized conditions typically found in a dry standpipe system.

In contrast, a wet standpipe system is continuously filled with water and does not require manual operation of a valve for immediate access. The dry standpipe with an automatic valve would have an automatic mechanism to control water flow without manual intervention. A yard hydrant system, while also providing a water source, operates under a different setup that is not directly related to building standpipe systems. Understanding the operation mechanisms of these different systems is crucial for effective emergency response and fire safety management.