Water columns are most commonly used to measure?

Water columns are commonly used to measure low pressure because they provide a simple and effective way to quantify the pressure exerted by a liquid. The height of the water column can be directly correlated to the pressure; as the pressure decreases, the height of the water column also decreases. This method utilizes the principles of hydrostatics where a column of water (or any liquid) can balance the pressure applied at its base.

In practical applications, water columns are particularly advantageous for measuring low pressures because they can easily indicate relatively small changes in pressure through noticeable changes in height. The use of liquids, like water, allows for a clear visual representation of pressure without the need for complex electronics or calibration that might be necessary with other devices for measuring high pressures or vacuums.

This measurement technique is less effective for high pressures, where specialized instruments like manometers or gauges designed for that specific range are more appropriate, as well as for vacuum conditions which require different measurement strategies. Temperature is measured using thermometers and other temperature-sensitive devices, making the use of a water column unsuitable for this purpose.