Which of the following is NOT a method of closing an emergency shutoff valve?

The choice indicating manual shutoff from a satellite orbiting the earth is not a feasible method for closing an emergency shutoff valve. This option illustrates an impractical scenario that lacks any realistic mechanism or technology for controlling local gas systems from such a distance. Emergency shutoff valves are typically designed for immediate and local responses to gas leaks or emergencies, requiring methods that can be deployed rapidly on-site.

In contrast, the other methods presented – manual control, remote control, and automatic closed-loop control – are all legitimate techniques commonly used in various contexts. Manual control involves physically operating the valve by an operator, which is both direct and effective for emergencies. Remote control allows for the shutdown of the valve from a distance, often through electronic systems, enhancing safety in hazardous situations. Automatic closed-loop control systems can trigger the valve closure in response to specific conditions (like detecting a leak), providing a crucial automated response to prevent gas from escaping without human intervention. Each of these options ensures that the gas supply can be effectively managed in critical situations, which ties back to the overall goal of safety in propane gas usage and installation.