Pressure-sensor based liquid-level measuring device with reduced capillary effect

A device for sensing or monitoring a level of a liquid within a container, the device comprising:

• a pressure sensor body comprising a sensing element;
• and
• a hollow tube of a chemically inert material substantially impervious to air, the hollow tube defining a tube length, the hollow tube comprising:
• a first end having a substantially air-tight connection to the pressure sensor body;
• a second end opposite the first end;
• an essentially cylindrical narrow portion extending from the first end and having a first inside diameter;
• an essentially cylindrical wide portion extending from the second end and having a first length and a second inside diameter, such that the ratio of the second inside diameter to the first inside diameter is from about 4:1 to about 10:1;
• a transition portion connecting the narrow portion and the wide portion and having a second length, such that the ratio of the sum of the second length and the first length to the first length is from about 1.2:1 to about 1.6:1 and the ratio of the sum of the second length and the first length to the tube length is from about 1:5 to about 1:15, the transition portion having a bell shape characterized a smooth upward curve and a smooth inward curve, the curves both having equal angles of curvature of from about 30° to about 60°;
• and
• an inner column defined within the hollow tube, the inner column being in fluid communication with the sensing element and extending from the first end to the second end,
• such that while the second end of the hollow tube is immersed in the liquid, a portion of the liquid extends into the inner column up to a column liquid level, a change in the column liquid level causing a corresponding change in pressure to a substantially constant mass of gas contained within the inner column, the change in pressure being measurable by the sensing element and directly related to the level of the liquid in the container.