What liquid is typically used to fill a "U" tube manometer?

A "U" tube manometer is an instrument used to measure pressure differences in fluids. The most common liquids used for filling a U-tube manometer are water and mercury due to their properties.

Water is often used in low-pressure applications because it is non-toxic and readily available. However, if the pressure being measured is high or if the differential pressure needs to be measured over a larger range, heavier liquids may be preferred.

Mercury is another common liquid used due to its high density, which allows for measuring larger pressure differences in a more compact manometer design. Its high density means that even a small pressure difference will cause a significant height difference in the mercury column, making it effective for accurate readings.

Heavy oils and light oils do not typically possess the appropriate physical properties needed for accurate manometer readings. They have varying densities and are often not used due to issues such as viscosity and surface tension that can affect the reliability of the readings.

While heavy and light oils can technically be used in certain niche applications, mercury is usually the best choice for precision and reliability in measuring pressure differences, especially in professional and scientific contexts. Therefore, the choice focusing on mercury aligns with the standards for liquid used in U-tube manometers, particularly