ASME containers with more than 2,000 gallons water capacity must have an opening for what?

The correct answer is that ASME containers with more than 2,000 gallons of water capacity must have an opening for a pressure gauge. This is essential for safe operation as it allows for continuous monitoring of the internal pressure of the container. Maintaining proper pressure within the tank is critical for ensuring the safe storage and handling of propane.

A pressure gauge provides operators with immediate visual feedback on the state of the container, enabling them to detect any changes or anomalies in pressure that could indicate potential problems, such as leaks or over-pressurization. Therefore, having a pressure gauge is a key safety feature that helps prevent accidents and ensures compliance with safety regulations.

While other options like safety valves and thermal sensors are also important components of propane systems, the specific requirement for a pressure gauge in this context is focused on monitoring pressure levels for containers of this size. Liquid level indicators are useful for knowing how much propane is left but do not address pressure management directly.