Measuring Solutions of Vibrating Rod Level Switch for Adhesive and Electrostatic Adsorbed Materials

In the field of automatic production, material level detection is a key link to avoid the materials in silos running out or overfilling, as well as to improve the efficiency in the production process. A variety of sensors are available for point level detection of solids, based on different output, and can be divided into point level sensors and continuous level sensors. Vibrating point level sensors are the most common, the vibration of the probe tends to eliminate build-up of material on the probe element due to its unique structure and excellent performance. But somehow, there are still some specific details that need to be taken care of.

Every medium has specific physical properties, even in different process links of the same working condition, the properties are sometimes different. For example, the water content of carbon black before wet granulation is different from that after coming out from the drying system. The former has a higher water content, which makes the powdery carbon black prone to build up and jam, while the latter contains less water and is in a dry powder state. In addition, some chemicals, such as soda, have strong hygroscopicity and are prone to caking when in high humidity. Usually, nitrogen sealing technology is used to prevent moist air from entering the tank. However, it is still inevitable to be affected by moisture and caking. Also, some materials (such as polyphenol A) also have the characteristics of light specific gravity and electrostatic adsorption. Focus on various complex working conditions encountered by users on Vibrating Rod Level Switch, we have listed in the following and carried out specific solutions.

Select the correct installed position with the right method

1. Installed position

Please avoid installing the instrument near the inlet point so that the vibrating tube does not protrude directly into the filling stream. It will prevent instruments from filling impact damage or generating false signals.

2. Installed method

For lateral installation, mount sensor approx.20°inclined to the vessel’s bottom to avoid medium buildup. To protect the probe from direct impact damage, a protection baffle should be installed above the vibrating body, and longer than intrusion depth (horizontal). Generally, a protection baffle can be a convex shape (inverted “V” section). If the medium is coarse and abrasive, baffle in concave shape (erected “v” section), so the medium could stack up a bit in the concave area. If available, the sensor should be mounted in a recess portion of the container to protect the probe from impacting or being bent by filling materials.

3. Additional steps

For the material with strong hygroscopicity, it is easy to cause media build-up of the vibrating probe. To properly solve the problem, it is suggested that the probe surface should be cleaned by blow purge regularly. Usually, the effect of short-time high-pressure purge is better than that of continuous low-pressure purge, and continuous purge will wear the probe. So, periodic short-term high-pressure purge is recommended.

Materials that are easy to be adsorbed by static electricity have stronger moisture adsorption, tend to be adsorbed and accumulate around the stainless-steel probe, resulting in the sensor triggering a false alarm signal. Spray anti-static paint or outer lined coating on the probe is an effective anti-static treatment. Besides, a protective sleeve with a length slightly longer than the vibrating probe can be welded around the probe to timely trigger the sensor to send the alarm signal when material is accumulated to the switching point, so as to avoid the accumulation caused by electrostatic adsorption. At the same time, the protective sleeve is more conducive to the formation of strong air flow, an additional blow purge is for a better effect.

Tube-11 Vibrating Rod Level Switch is designed with double vibrating tubes, which prevents bulk material from getting stuck or jammed, and can be stably and reliably used for level measurement under most severe working conditions.