Overview

HM-90(30) Series is a Displacer Type Level Switch installing on the top of tank, operated with the usage of buoyancy to the displacer and spring tension. It is generally used to control liquid level for high temperature and pressure process with On/Off contact signal.

Characteristics

- Strong structure and long life cycle

- Easy installation

- Applicable to explosion area (Ex-Proof version)

- Widely used to detect various liquid levels

- Available to use for high temperature and pressure process

Operation Principle

Displacer Type Level Switch is operated based on Archimedes principle that the weight of objects in liquid becomes lighter as much as the weight of liquid flowing over. That object is called by displacer instead of float because it is impossible to float for itself. When a displacer is immersed in a liquid, displacer becomes lighter due to a buoyancy force and this force is transferred to spring. While the loosened spring is constructed due to the gained buoyancy force, rising core moves a magnet by magnetism and finally switch is operated. As described in below [Fig 1] and [Fig 2], the buoyancy force F can be expressed by the following equation.

F = r X s X I

[r=Specific gravity of liquid, s=Cross section area of displacer, l=Buoyancy of submerged displacer]

As the displacer is immersed in a liquid [Fig 2], displacer becomes lighter due to a buoyancy force and this force is transferred to spring. After that, the compressed spring [Fig 1] by the weight of displacer is loosened [Fig 2] due to the gained buoyancy force and then the core rises. The rising core moves the magnet and it activates the switch.

Specification