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    How to use a DP (differential pressure) transmitter for level measurement?

    Question: How to use a DP (differential pressure) transmitter for level measurement?

    Answer:

    A differential pressure transmitter gives a linear output for the differential pressure measured across its HP and LP chambers.

    Connect the transmitter’s HP leg to the bottom of the tank and its LP leg to the top of the tank. The transmitter [...]

    Why is a gap controller often used in controlling a level in a high pressure vessel?

    Question: Why is a gap controller often used in controlling a level in a high pressure vessel?

    Answer:

    Gap controllers output changes from minimum to maximum and visa versa when the process measurement deviates the setpoint by the set gap. Hence the final control element i.e. control valve acts like an on-off valve. This [...]

    Why is static head level transmitter more suitable than a leveltrol on a surge tank?

    Question: Why is static head level transmitter more suitable than a leveltrol on a surge tank?

    Answer:

    A leveltrol has a limitation in measuring the maximum height of liquid. Considering huge of the surge tank, a static head level transmitter is more suitable.

    Why is a leveltrol more suitable than a static head level transmitter on a separator?

    Question: Why is a leveltrol more suitable than a static head level transmitter on a separator?

    Answer:

    Leveltrol is more accurate in measuring the small height of liquid level. The process pressure change does not affect the leveltrols performance. Leveltrol offers a high gain output verses the change in the liquid level.

    How to calibrate a static head level transmitter for an interface measurement?

    Question: How to calibrate a static head level transmitter for an interface measurement?

    Answer:

    Static head level transmitter is not commonly used for measuring the interface level. But the following procedure may be used for calibrating it to measure the interface level in a tank.

    Fill the vessel 100% with the lower density liquid and [...]

    How to calibrate a leveltrol for an interface level measurement?

    Question: How to calibrate a leveltrol for an interface level measurement?

    Answer:

    Fill the leveltrol chamber 100% with the lower density liquid and adjust its zero for 4.00mA output.

    Drain the liquid and fill the leveltrol chamber 100% with the higher density liquid and adjust its span for 20.00 mA output.

     

    The transmitter [...]

    What is an interface in level measurement?

    Question: What is an interface in level measurement?

    Answer:

    An interface is the separation point between the two de-miscible liquids levels in a vessel. This condition arises when the liquid does not mix due to its chemical composition and difference in their density.

    Zero suppression and Zero elevation in level measurement?

    Question: What is Zero suppression and Zero elevation in level measurement?

    Answer:

    Zero suppression: when a static head transmitter is installed below the zero liquid level, the transmitter gets a +ve error in the level measurement. This error is corrected by a zero suppression kit.

     

    Zero elevation: when a static head transmitter is [...]

    What type of level measuring instrument is suitable for closed tank?

    Question: What type of level measuring instrument is suitable for closed tank?

    Answer:

    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 a static head or a differential pressure transmitter with its HP leg connected to [...]

    Points to consider while selecting a level switch for a particular process

    Question: What are the points to consider while selecting a level switch for a particular process?

    Answer:

    While selecting a level switch, the following points are to be considered:

    - The characteristic of process (corrosive or non – corrosive)

    - The process pressure

    - The liquid density

    - The flange ratings

    - Proof pressure of [...]