Limitations and Selection of Rotary Paddle Switch
Rotary paddle switch has been used in various locations where powder and bulk goods must be detected. Rotary paddle type level switch is based on electromagnetic principle. It works when an electric motor drives the shaft connected to the rotating paddle. The rotating paddle is continuously rotates by a motor. When this paddle contacts with the material, the force more than the rotating torque will be applied to the paddle and the rotation will stop. As the level moves down, the paddle rotates freely when uncovered.
Rotary paddle switch is developed with a simple and reliable measurement standard and is free to maintain. It has been widely used in chemical, plastic, cement, pharmaceutical, fodder, food and other industries.
Due to the variety of working conditions, there are different requirements for the selection of level switches, as well as rotary paddle switch.
The smooth operation of rotary paddle switch is inseparable from the precise coordination between the motor, shaft, bearing and the oil seal technique. Its mechanical structure can measure the level of granular and powdery media reliably. But wet powders can be easily hung on the shaft and paddle, and it is easy to scar, or, caking (as shown in the figure below). The “scar” hinders the rotation of paddle. With the accumulation of “scar blocks”, the motor cannot drive the rotation normally, which is mistakenly considered as the state of material covered and output a false alarm signal.
Furthermore, moist materials are high in volume and weight, which cause serious deformation of the paddle and shaft, resulting in abnormal operation.
Generally, rotary paddle switch is used to measure the level of dry materials rather than materials with strong hygroscopicity or high moisture. If there are no alternatives, to ensure smooth operation, the paddle and shaft must be cleaned regularly to avoid hanging and caking.
Spin -11 Rotary Paddle Switch series operate reliably and maintenance-free and offers a compatible solution for plants for safe level detection in bulk solids; with gas and dust explosion proof certificates (Ex d IIC T6 Gb；Ex tD A21 IP65 T80℃), as well as dual bearing design, stable operation and long life time in service; can be applicable in a wide range and passed by IP65 Ingress Protection rating.
