A main drain shall be provided on the standpipe ________ side of the system control valve.

A main drain shall be provided on the standpipe ________ side of the system control valve.

• A. standpipe
• B. system
• C. pump
• D. valve

Answer: (B)

Main idea: the main drain needs to be placed on the side of the system control valve that leads to the standpipe so the standpipe can be drained for testing and maintenance without affecting the water supply side. By locating the drain on the standpipe side of the valve, you can isolate the system with the control valve and still discharge the water from the standpipe through the drain. This makes hydrostatic testing and routine maintenance practical, because the water in the standpipe can be drained out safely while the supply side remains protected from backflow or unintended discharge. If the drain were on the opposite side, closing the system control valve could prevent proper draining of the standpipe or complicate the test setup, since the standpipe wouldn’t have a clear path to the drain independent of the supply.

Main idea: the main drain needs to be placed on the side of the system control valve that leads to the standpipe so the standpipe can be drained for testing and maintenance without affecting the water supply side. By locating the drain on the standpipe side of the valve, you can isolate the system with the control valve and still discharge the water from the standpipe through the drain. This makes hydrostatic testing and routine maintenance practical, because the water in the standpipe can be drained out safely while the supply side remains protected from backflow or unintended discharge. If the drain were on the opposite side, closing the system control valve could prevent proper draining of the standpipe or complicate the test setup, since the standpipe wouldn’t have a clear path to the drain independent of the supply.