At all times, which valve must remain closed?

The container valve must remain closed at all times to ensure the safe handling and storage of non-flammable compressed gases. Keeping the container valve closed prevents the escape of gas, reducing the risk of pressure buildup, accidental release, or leakage, which can pose hazards such as asphyxiation or environmental contamination.

When the container valve is closed, it also minimizes the risk of external contaminants entering the container, which can lead to dangerous chemical reactions or affect the integrity of the gas within. Additionally, by keeping this valve closed, operators maintain better control over the gas supply, leading to safer operational practices.

In contrast, the control valve, safety valve, and pressure relief valve serve different critical functions. The control valve regulates the flow of gas as needed, the safety valve ensures that pressure does not exceed safe limits by releasing excess pressure, and the pressure relief valve serves a similar purpose. Each of these valves operates within specific parameters and may be opened or closed in response to system demands, thus requiring more flexible management compared to the container valve.