Application of Jiwei Fork Liquid Level Switches in Pump Control for Underground Tanks
One of our customers proposed a technical renovation project involving level measurement for their underground tanks and pump control. They aimed to use a liquid level sensor to output three alarm switching signals to control the operation (ON/OFF) of three centrifugal pumps and avoid safety incidents due to medium overflow or pump damage caused by dry running.
The stored material in the underground tank is acidic, and steam is present in the tank. The measured material contains many impurities, and the liquid level fluctuates greatly. These special working conditions require high-quality and high-performance level meters. The customer compared various common liquid level measuring instruments such as ultrasonic level transmitters, radar level meters, float level indicators, magnetostrictive level meters, and float level switches. However, none of these met the requirements of the application.
Ultrasonic level transmitter: The ultrasonic level transmitter sends out mechanical waves, with the probe both transmitting and receiving signals. If there is steam in the working area of the probe, the transmission and reflection of the ultrasonic waves will be disturbed, affecting the accuracy of the measurement. Therefore, it is not recommended for this application.
Radar level meter: The radar level meter emits electromagnetic waves. Water vapor can condense on the surface of the probe and generate interference signals. Fluctuations on the liquid’s surface can generate false echo emissions. Although some manufacturers include echo suppression in the signal receiving process to mitigate false echo signals to some extent, when the steam is thick and the liquid level fluctuates greatly, the radar level meter is not reliable for level measurement. Additionally, it is expensive.
Float level indicator: The magnetic float moves up and down along a connecting rod and triggers certain reed switches inside the rod to close the blades and output different currents accordingly. However, because the measured fluid contains impurities, the float is prone to getting stuck. Therefore, it cannot work reliably in this situation. A similar problem also exists with a magnetostrictive level meter.
Float level switch: This switch has a simple structure, primarily for civilian use. It is not recommended for applications with fluctuating liquid surfaces and acidic working environments. It is especially not suitable for large tanks due to installation challenges and unreliable performance.
Jiwei Ring-11 Fork Liquid Level Switch outputs a switching signal by detecting changes in the vibration frequency of the probe. It is completely unaffected by steam. The detection delay can be set to avoid disturbances from liquid surface fluctuations. Wetted parts such as fork bodies and fitting flanges can be made of 316L stainless steel with ECTFE or PFA coatings, making them suitable for level measurement of strong acidic and alkaline liquids. The fork body of Ring-11 is precisely tuned to have greater redundancy for material buildup. Based on the onsite working conditions, Jiwei’s sales engineers proposed an onsite installation solution for the customer.
As shown in the diagram above, three Ring-11 Fork Liquid Level Switches are installed with flange process fittings at the top of the underground tank. The distances from the alarming points of the level switches to the flange surface (insertion depths) are 1500mm, 1000mm, and 500mm, respectively. They control the operation of three pumps. Since the installation and use of these instruments, the advantages of the Ring-11 Fork Liquid Level Switch, such as strong corrosion resistance, high measurement accuracy, greater redundancy for material buildup, and freedom from disturbances caused by material stirring or medium fluctuations, have been outstanding, effectively solving level measurement problems for the customer. Jiwei Ring-11 Fork Liquid Level Switch meets all requirements for this application under these complex working conditions. Three units of the Ring-11 have been working stably and reliably for about half a year since their installation and have received positive feedback from the customer.
Jiwei Ring-11 Fork Liquid Level Switch has an ingress protection rating of up to IP66/IP67. It has dual explosion protection certificates for both Intrinsic Safety and Flameproof Enclosure. It is widely used in the petrochemical, food processing, pharmaceutical, metallurgical, and water treatment industries, among others.