Which manometer is typically used for measuring very low pressures or vacuums?

The inclined manometer is specifically designed for measuring very low pressures or vacuums due to its enhanced sensitivity. By tilting the liquid column, the inclined manometer increases the length of the liquid column for a given pressure change, allowing for more precise readings at low pressure levels. This increased length allows even small pressure changes to be detected more accurately, making it ideal for applications where precision is critical.

In contrast, other options serve different functions or are designed for different pressure ranges. The Bourdon tube, while effective for measuring higher pressures, does not have the same sensitivity for very low pressures. Concentric orifices are more suited for flow measurement rather than direct pressure readings, and closed-loop systems refer to a type of control system rather than a specific method for measuring pressure. Therefore, the inclined manometer is the optimal choice for low pressure applications.