What is the best way to properly close a service valve on a propane tank?

Tightening a service valve on a propane tank with your hand ensures that it is securely closed without applying excessive force that could damage the valve or create a leak. This method allows for a gentle yet effective closure, maintaining the integrity of the valve and the seal. By using your hand, you can also judge the resistance and avoid overtightening, which could cause harm to the valve mechanism itself.

Other methods, like using a hammer, can lead to physical damage to the valve, while forcing it closed can risk damaging the threads or affecting its operation. Allowing it to close naturally isn't advisable, as it may not guarantee a complete seal, which is crucial for safety when dealing with pressurized propane. Therefore, the most effective and safe approach is to tighten the valve with your hand.