Application of Tuning Fork Level Switches in Measuring Floating Medium in Water

Recently, Jiwei Fork-11 Tuning Fork Level Switches were successfully operated in PVDF interface level measurement in a chemical factory.

Polyvinylidene fluoride or polyvinylidene difluoride (PVDF)is a semi-crystalline thermoplastic fluoropolymer. Polyvinylidene fluoride (PVDF) resin mainly refers to the homopolymer of vinylidene fluoride or the copolymer of vinylidene fluoride and a small amount of other vinylidene fluoride monomers. It has the characteristics of both fluororesin and general resin. The resin itself has good chemical corrosion resistance, high temperature resistance, oxidation resistance, weather resistance, radiation resistance, as well as piezoelectric, dielectric, thermoelectric and other special properties, so it is widely used in high-end functional films such as piezoelectric film, solar back plate film, lithium battery diaphragm, etc.

Difficulties

The production process of PVDF requires at least 6 washes to obtain a high-purity finished product. After stirring and dispersing, VDF monomers are suspended in the form of droplets in the dispersed medium of deionized water. In previous washing processes, staffs were arranged to monitor the level. When the discharged liquid changed from pure water to white VDF monomer, the control room was notified to close the discharge valve. However, the density of VDF monomer is extremely close to that of water, and it is floating on water, failure to close the valve in a timely way leads to VDF loss. The monitor of floating medium in water has always been a challenge for the industry.

Jiwei Solution

After receiving client inquiries, Jiwei engineer communicated with the client and required 6 buckets of VDF s monomer samples from different production process. For different processes, the VDF monomer in water becomes thinner, so the density of floating VDF monomer in the water becomes closer to that of water, making it more difficult to accurately measure the interface.

We analyzed the different working conditions of different process media and continuously adjusted the frequency and amplitude of the fork in water and in various processes to achieve the optimal balance point in each process, ensuring the fork does not alarm in water. Only if VDF monomer float in the water and come into contact with the fork, an alarm signal will be issued.

Fork-11 Tuning Fork Level Switch probe is based on a tuning fork harmonic resonance. It utilizes piezoelectric devices to drive the fork to vibrate and detect the changes of vibration. The fork vibrates in resonant frequency when it is in air. Once the fork comes into contact with application medium, the vibration amplitude of the fork will decrease substantially. Output from the detecting piezoelectric device will decrease accordingly. An integrated circuit is designed to analyze the amount of decrease and output a switch signal. By reasonably increasing the area of tines and precisely adjusting harmonic resonance, Jiwei Fork-11 Tuning Fork Level Switch offers great reliability and sensitivity:

●　Reasonable design of tines and precisely adjusted of fork resonant frequency. Fork-11 can be used in light powders and flakes with bulk densities as low as 0.008g/cm³.

●　Particularly suits for level measurement of powdery, fine-grained bulk solids, can effectively avoid buildup.

●　With the suspension cable, Fork-11 can be applied in tall and narrow silo.

●　Industry-leading performance for high temperature industrial environments, can tolerate process temperature up to 400℃.

●　Strong self-diagnostic function helps to accurately locate the fault.

●　Easy installation and maintenance free.

●　With CE certificates, gas and dust Flameproof Enclosure and Intrinsic Safety certificates.

●　Made of strong corrosion resistant material 316L.