What instrument is typically used to measure vacuums?

The instrument commonly used to measure vacuums is a manometer. A manometer is designed to measure pressure differences and can accurately indicate vacuum levels, which are essentially pressures below atmospheric pressure. Operating on the principle of liquid columns, a manometer can give precise readings of how much below atmospheric pressure the vacuum situation is, by measuring the height difference of a liquid column typically contained within a U-shaped tube.

In contrast, while a vacuum transducer may provide electronic measurements and conversions of vacuum levels, it is not as direct for simple readings as a manometer. A Venturi is a device used to measure flow rates and isn't designed for vacuum measurement. A vacuum cup is an accessory used in pneumatic systems for holding or lifting objects in a vacuum state, but it does not measure vacuum levels. Therefore, the manometer stands out as the most applicable instrument for directly measuring vacuums.