# Level measurement interview questions **URL:** \ **Category:** Instrumentation\ **Tags:** level-measurement, interviewquestions\ **Created:** [January 25, 2018, 12:35pm UTC](https://forumautomation.com/t/level-measurement-interview-questions/3029 "2018-01-25T12:35:50Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![areejsidhik](https://forumautomation.com/letter_avatar_proxy/v4/letter/a/ee59a6/32.png) [@areejsidhik](https://forumautomation.com/u/areejsidhik)\ **Post date:** [January 25, 2018, 12:35pm UTC](https://forumautomation.com/t/level-measurement-interview-questions/3029/1 "2018-01-25T12:35:50Z")
> **What is level?** The total quantity of substance stored in a tank or vessel. > **Different types of level measurement instruments used in industries are** Gauge glass, pressure gauge -scale graduated in %of level, rope and weight, dipsticks, hydrostatic methods, purged methods, displacer methods, load cells, nuclear methods, capacitance, ultrasonic methods etc. > **Explain how a leveltrol works?, Name the parts of leveltrol?** As the name indicates it is used for measuring level.The leveltrol works on the buoyancy principle .leveltrol has a float chamber which contains float submerses proportionately with a liquid level rise.The amount of submersion of displacer depends on the liquid density, which produces a torque. The amount of torque produced is measured in terms of %level. **Parts of leveltrol:** Float, float chamber, torque lever, knife edge, feedback bellows, air relay, restriction, flapper, nozzle > **What type of level measuring instrument is suitable for a closed tank?** If the level measurement is required for a fixed and small height, a leveltrol is more suitable. If it is for a total height, then either static head or a differential pressure transmitter with its HP side connected to the bottom of the tank and LP side connected to the top of the tank to a gas phase. > **What are zero suppression and zero elevation in level measurement?** _ **Zero suppression:** _ when a static head transmitter is installed below the zero liquid level the transmitter gets a positive error in level measurement. This error is corrected by a zero suppression kit. _ **Zero elevation:** _ when a static head transmitter is connected above zero liquid level the transmitter gets a negative error in level measurement. This error is corrected by zero elevation kit. > **What is the interface in liquid level measurement?** An interface is the separation point between the two dismissible liquids levels in a vessel, the condition arises when the liquid does not mix due to its chemical composition and difference in density. > **How to calibrate a leveltrol for an interface level measurement?** Fill the leveltrol chamber 100% with the lower density liquid and adjust its zero for 4 ma output. Drain the liquid and fill the leveltrol chamber 100% with the higher density liquid and adjust its span for 20 ma output. > **Why is static head level transmitter more suitable than a leveltrol in surge tank?** A leveltrol has a limitation in measuring the maximum height of liquid. Considering huge surge tank static head transmitter is more suitable. > **State the difference between float and displacer?** Float is used in level switch (6 inches) The displacer is used in the level transmitter. (14inch, 48inch, 60inch, 72inch) > **Write the formula for calculating a static head in Kpa?** **_Static head = qgh_** q=density of the liquid g =gravity h= height of the liquid column > **What happens if the displacer has a hole in it, what will be the output of that leveltrol mechanism?** The output will be minimum ie 4MA. > **What will be the output if the displacer fell down in online?** The output will be maximum ie 20MA.