Gauge Glass

A very easy means through that liquid level is measured in a vessel is through the gauge glass method that was display in the figure.  Within the gauge glass method and a transparent tube is attached to the bottom and top (top connection not required in a tank open to atmosphere) of the tank which is monitored.  A height of the liquid in the tube will be equal to the height of water inside the tank.

Figure: Transparent Tube

Above figure describes a gauge glass that is used for vessels where the liquid is at pressure conditions and ambient temperature.  Below figure describes a gauge glass that is used for vessels where the liquid is at an elevated pressure or a partial vacuum.  Remember that the gauge glasses in Figure efficiently form a "U" tube manometer where the liquid seeks its own level due to the pressure of the liquid within the vessel.

Gauge glasses established from tubular glass or plastic are used for service up to 450 psig and 400°F. A different type of gauge glass is used if it is desired to measure the level of a vessel at higher temperatures and pressures.  The category of gauge glass utilized in this object has a body made of metal along with a heavy glass or quartz section for visual observation of the liquid level.  The glass section is commonly flat to give strength and safety.  Below Figure describes a classical transparent gauge glass.

Figure: Gauge Glass