To facilitate travel, many cities have subways. In subway stations, there are many water collection wells, domestic sewage tanks and other places. The water levels in these wells or pools need to be monitored in real time to avoid overflow, especially in seasons when rain is concentrated. A liquid level controller is required to drain this water in a timely manner. Several liquid level gauges that are commonly used now include: 1. Float level controller; 2. Submersible level gauge; 3. Ultrasonic level gauge.

In the early days, float level controllers were mostly used because they were relatively simple and easy to install. It is widely used in pump valve control. But it also has disadvantages, and its lifespan is relatively short. Generally, it needs to be replaced every 5-6 months.

Submersible level gauges are now the most widely used liquid level controllers. Analog output can monitor the current liquid level in real time. High precision, easy installation and relatively reasonable price. From the cable-type submersible liquid level gauge at the beginning, it has transitioned to the current collector-type submersible liquid level gauge. Improved the problem that the submersible liquid level gauge is easily blocked by sludge. Long service life.

As a new liquid level controller, ultrasonic liquid level gauge was initially introduced from abroad. High price, accurate measurement, non-contact measurement. It has been welcomed by many users and is used as the first choice for design by many design institutes. However, many on-site situations are relatively complex, and it would be awkward to choose an ultrasonic liquid level meter. The water collection well is too small and too shallow. The blind spot shortcomings of ultrasonic liquid level gauges are more troublesome. If the installation is not chosen well, it is easy for the liquid level to enter the blind zone and then flood the ultrasonic liquid level meter. Through the efforts of the Chinese people, the performance of domestic ultrasonic level meters is also very good and can completely replace imported products. And the after-sales service is relatively good, and it has received support from many users.

Nowadays, in liquid level control, float level control, input level gauge, and ultrasonic level gauge are all commonly used, and users will use them differently according to the actual situation on site.