Application of Jiwei Fork Liquid Level Switch in Pump Control for Underground Tanks

The stored material in the underground tank is acidic. Steam exists in the tank. The measured material contains many impurities and the liquid level fluctuates greatly. The special working conditions require high quality and high performance of level meter. The customer made a comparison between common liquid level measuring instruments such as ultrasonic level transmitter, radar level meter, float level indicator, magnetostrictive level meter, and float level switch etc. and found out none of them met the requirements of the application.

1. Ultrasonic level transmitter: The ultrasonic level transmitter sends out mechanical waves. The probe can both transmit and receive signals. If there is steam in the working area of the probe, the transmission and reflection of the ultrasonic waves will be disturbed, thereby accuracy of the measurement will be affected. So it is not recommended for this application.

2. Radar level meter: Radar level meter emits electromagnetic waves. Water vapor is easy to condense on the surface of the probe and generate interference signals. Fluctuations on the surface of the liquid can generate false echo emissions. Even though some manufacturers add echo suppression into the signal receiving process to overcome the false echo signal to some extent, but when the steam is thick and the liquid level fluctuates greatly, radar level meter is not reliable in the level measurement. In addition, it is expensive.

3. Float level indicator: The magnetic float moves up and down along the connecting rod, and triggers certain reed switch inside the connecting rod to close the blades and output different current accordingly. But because the measured fluid contains impurities, the float is prone to be stuck sometimes. It can´t work reliably in this situation. Similar problem also exists with a magnetostrictive level meter.

4. Float level switch: It has a simple structure, mainly for civilian use. It is not recommended to be used in the application where the liquid surface is fluctuating and under acidic working environment. It is especially not recommended for large tanks because it is impossible to be installed and it can´t work reliably.

As shown in the diagram above, on the top of the underground tank, three Ring-11 Fork Liquid Level Switches are installed with flange process fitting. The distance from alarming point of the level switches to flange surface (insertion depth) is 1500mm, 1000mm, and 500mm respectively and they are used to control the operation of three pumps. After the instruments were installed and put into use, the advantages of Ring-11 Fork Liquid Level Switch such as strong corrosion resistance, high measurement accuracy, larger redundancy for material buildup and free of disturbance from material stirring or medium fluctuation were outstanding and solved level measurement problems for the customer. Jiwei Ring-11 Fork Liquid Level Switch meets all requirements for the application under these complicated working conditions. Three units of Ring-11 have been working stable and reliable for about half a year since their installation. They have been well evaluated by the customer.