When measuring level with a float, what is used if installation within a vessel is impractical?

In situations where a float cannot be installed directly within a vessel due to space constraints or other practical reasons, a float cage is employed. A float cage allows for the float to be positioned outside the vessel while still being able to accurately measure the liquid level inside. This is particularly useful in large or complex installations where direct access to the fluid being measured is limited.

The design of a float cage typically involves a framework that holds the float securely while maintaining its ability to rise and fall with the liquid level, allowing for consistent and reliable measurements. It minimizes potential risks that might arise from having equipment directly within the vessel, such as mechanical obstructions or contamination.

In contrast, the other options listed, while useful in various contexts of level measurement, do not specifically address the need for an external solution when the float cannot be installed directly inside the vessel.