Level Measurement

defined as the “determination of the

position of an existing interface between two media.”

is simple, almost

straightforward and economical; it uses a measurement

of the distance (usually height) from the datum line, and used

primarily for local indication. It is now easily adopted to signal

transmission techniques for remote indication or control.

flexible linesfitted with end weights called _ have been used for centuries by seafaring men to gauge the depth of water under their ships.

stored conveniently

in a reel are still used extensively for measuring level in fuel

oil bunkers and petroleum storage tanks.

It is

quite straightforward in use; the

level in the glass seeks the same

position as the level in the tanks.

perhaps the simplest indicating

instrument for liquid level in a vessel. They are often found in

industrial level-measurement applications, even when another

level-measuring instrument is present, to serve as a direct

indicator for an operator to monitor in case there is doubt

about the accuracy of the other instrument.

The visual means of level measurement previously

discussed are rivaled in simplicity and dependability by float

type measurement devices.

level measurement

depend on the material having a physical property which

can be measured and related to level. Many physical and

electrical properties have been used for this purpose and are

well suited to producing proportional output signals for

remote transmission. This method employs even the very

latest technology in its measurement.

Uses the theory of Archimedes Principle which states

that “the force produced when a body is submerged into

liquid with a constant density is equal to the fluid displaced”;

A vertical column of fluid generates a pressure at the bottom

of the column owing to the action of gravity on that fluid. The

greater the vertical height of the fluid, the greater the pressure, all

other factors being equal.