Threaded joints shall be allowed on the source equipment on which side of the source valve?

Threaded joints are essential components in ensuring the integrity and safety of medical gas systems. The correct choice indicates that threaded joints are permissible on the source equipment on the side of the source valve. This is significant because the source valve is crucial for controlling the flow of medical gases and ensuring that the system is safely isolated when maintenance or repairs are necessary.

Having threaded joints on the source side of the valve allows for secure connections that can handle the pressures associated with medical gases. This placement avoids potential leaks that can arise from joint failure, ensuring both safety and reliability within the medical gas supply system.

In contrast, having threaded joints in other positions, such as downstream from the source valve or on alarm pressure switches, could present risks, such as leaks that may lead to a loss of gas or compromised system integrity. Thus, the fabrication practices that allow threaded joints only at the source ensures a higher level of safety and operational efficiency.