Level Measurement

What is a hook type level sensor? Why do we need a hook type indicator?

The hook type level sensor is a direct level measurement, this type of level indicator has a wire which could be corrosion resistance alloy and this would be bent into U-shaped with one arm longer than the other. In this device it has a hook that is connected to a micrometer cylinder and this device has arms that are situated in a still well and the still well would keep away the ripples from the device and these ripples would be from the process that is being measured and also it equalizes the water level.

If the level of the liquid in an open tank needs to be measured in a scale, this scale could be in the liquid or outside it. So it will be very difficult to check the level because of the errors. So we can use a hook type level indicator for this case.

How hook type level indicator is constructed?

This device has a wire of corrosion resistance alloy, and this is bent into U shape and one arm is longer than the other. The shorter arm is pointed at 60 degrees and the longer arm is attached to a slider in the vernier scale, which moves over the main scale and shows the reading. This type of sensor has a hook that is pushed below the surface of the liquid to measure the level of the liquid and then the hook will be raised gradually. This principle is also used in measuring point manometer.

How to select a hook type level indicator?

  • We must consider the density and viscosity
  • The process temperature and pressure must be considered
  • We must also consider the ambient temperature and the process of agitation
  • Chemical composition
  • Interfaces and gradients must be considered
  • We must also consider the process conductivity and dielectric constant
  • Vibration and material build-up must be considered too

How does a hook type level indicator operates?

In the hook type level indicator, the hook will be placed or pushed below the surface of the process fluid that is to be measured. This hook will be raised until the point is just about to break through the surface. After that, it would be clamped and the level could be checked on the scale. This device can measure the water level very accurately by measuring the small changes in the water level and it can do the measurement in an open or closed tank.


post-graduate in Electronics & communication.

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