What are the different classes of level measurement? Explain any two level measurements with a neat sketch.
Answers
Answer:
Types of Level Measurement
Two methods used to measure level;
Direct or Mechanical method, and
Indirect or Inferential methods.
1. Mechanical or Direct Method
Direct level measurement is simple, almost straightforward and economical; it uses a direct measurement of the distance (usually height) from the datum line, and used primarily for local indication. It is not easily adopted to signal transmission techniques for remote indication or control.
c. Chain or Float Gauge
The visual means of level measurement previously discussed are rivaled in simplicity and dependability by float type measurement devices. Many forms of float type instruments are available, but each uses the principle of a buoyant element that floats on the surface of the liquid and changes position as the liquid level varies.
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LEVEL MEASUREMENT
Types of Level Measurement
S Bharadwaj ReddyFeb 17, 20171
Float Level Measurement
Types of Level Measurement
Two methods used to measure level;
Direct or Mechanical method, and
Indirect or Inferential methods.
1. Mechanical or Direct Method
Direct level measurement is simple, almost straightforward and economical; it uses a direct measurement of the distance (usually height) from the datum line, and used primarily for local indication. It is not easily adopted to signal transmission techniques for remote indication or control.
a. Dip Sticks and Lead Lines
Flexible lines fitted with end weights called chains or lead lines have been used for centuries by seafaring men to gauge the depth of water under their ships. Steel tape having plump bob – like weights, and stored conveniently in a reel are still used extensively for measuring level in fuel oil bunkers and petroleum storage tanks. (see figures below)
b. Sight Glass
Another simple method is called sight glass (or level glass). It is quite straightforward in use; the level in the glass seeks the same position as the level in the tanks. It provides a continuous visual indication of liquid level in a process vessel or a small tank and are more convenient than dip stick, dip rod and manual gauging tapes.
c. Chain or Float Gauge
The visual means of level measurement previously discussed are rivaled in simplicity and dependability by float type measurement devices. Many forms of float type instruments are available, but each uses the principle of a buoyant element that floats on the surface of the liquid and changes position as the liquid level varies.
B. Inferential or Indirect Methods
Indirect or inferred methods of 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.
Included in these methods are;
A. Buoyancy :-
the force produced by a submerged body which is equal to the weight of the fluid it displaces.
B. Hydrostatic head :-
the force or weight produced by the height of the liquid.
C. Sonar or ultrasonic :-
materials to be measured reflect or affect in a detectable manner high frequency sound signals generated at appropriate locations near the measured material.
D. Microwave :-
similar to ultrasonic but uses microwave instead of ultrasonic beam.
Explanation:
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