The anti rotation level gauge is a commonly used level switch for measuring the level of solid particles, powders, and other materials. Due to its simple working principle, easy operation, and affordable price, it is widely favored by users. However, the working conditions in the field of level measurement are diverse and complex, and different working conditions have strict requirements for the selection and installation of resistance rotary level switches. Among them, the most typical and complex working conditions are the measurement in heavy water vapor and humid materials. This article discusses the application of anti rotation level switches in measuring materials with water vapor or moisture.

In principle, anti rotation level switches are mostly used to measure the level of dry materials, and are not recommended for materials with strong moisture absorption, as this is mainly determined by their own structure. We know that the smooth operation of the anti rotation level switch relies on the precise coordination between the motor and the transmission shaft, the transmission shaft and the bearing, and the oil seal. Materials with water vapor or moisture are prone to "scar" at the end of the spindle (as shown in Figure 1), and over time, they will accumulate and run inside the probe, causing an increase in resistance to the spindle rotation and affecting the normal rotation of the blades. Ultimately, the motor cannot drive the spindle rotation, resulting in the output of incorrect switch signals. Furthermore, wet solid materials are prone to clumping, resulting in large and heavy blocks or clumps. This type of material can impact the anti rotation blades and transmission shaft, easily causing severe deformation of the blades and transmission shaft, thereby damaging the equipment and causing it to malfunction.

Does the anti rotation level switch mean that it cannot be used for measuring the level of water vapor or damp materials? The answer is certainly not. Different material characteristics can have a significant impact on the service life of instruments, and what we need to do is how to avoid adverse factors. After extensive testing and analysis by Xinmin Automation engineers, it has been found that the following measures are highly beneficial for the application of anti rotation level switches in measuring the level of materials with water vapor or moisture.

1、 The anti rotation level switch is installed at a 20 ° angle to the horizontal plane

Compared to horizontal installation, inclined installation can reduce the accumulation of materials on the sealing end face of the spindle during the feeding process, thereby reducing the entry of moisture, material running, and scarring.

2、 Install V-shaped baffle

The anti rotation level switch belongs to the contact type level switch, and it is a basic requirement to install it away from the direction of the discharge port. It is necessary to install a V-shaped protective baffle above the anti rotation level switch to avoid direct impact of clumped materials on the pages. At the beginning of the design of some silos, due to insufficient consideration, V-shaped baffles were not installed. Unlike shafts protected by protective sleeves, the blades were unable to withstand the impact of wet and clumping materials such as sludge due to poor stiffness, resulting in blade deformation of 90 degrees.

In addition, when installing V-shaped protective barriers, it is necessary to consider whether the space between the protective barrier and the spindle is too small, because wet materials have poor fluidity and are prone to clumping, which can easily accumulate in narrow spaces (dead zones) and form hanging materials.

3、 Change the silo structure design to a niche style design

Because the design of the silo and the matching of the instruments are two independent parts, the structural design of the silo usually does not consider the protection of the instruments, which undoubtedly increases the risk of using the anti rotation level switch. In addition to the installation of baffles, the design of converting the silo into a niche style can also effectively avoid the above risks. New Min will introduce it with practical application cases of users as an example.

Figure 2 Sludge discharge device

Figure 2 shows the sludge discharge device. After the silo is full, the sludge is transported away by the screw conveyor below. Due to the small space of the silo, the impact on the probe of the anti rotation material level switch during material discharge is extremely huge. The ideal design is to adopt a niche style design, so that materials can avoid being fed from the blades of the anti rotation level switch. When the materials piled up from bottom to top slowly move up to the blade position, the blades of the anti rotation level switch will contact the materials and output an alarm signal. Therefore, to avoid the positive impact of materials on the blades and the occurrence of material clamping in the dead zone, it is recommended to retrofit the silo into a niche structure design (as shown in Figure 3),

Figure 3 niche type silo