When using a liquid level gauge, apart from understanding its normal use and maintenance, one must also master certain basic maintenance methods. Commonly used maintenance methods include the panel compression method, direct perception method, tracing method, and comparison and substitution method. These methods are explained below.

1. Direct perception method: The direct perception method is a method of making judgments using the direct senses of the eyes, ears, nose, and hands. It is an indispensable auxiliary means in maintenance. It can be combined and applied throughout the entire maintenance process, from the department level to the specific point level. It is sometimes particularly important when identifying faults and locating points.

2. Testing and identification method: The testing and identification method is a method of quantitatively identifying circuit data using instruments. It is a basic method commonly used for compressing fault paths and points. The testing and identification method is divided into two types: power-on testing and power-off testing. Power-on testing includes testing of voltage and current related to the liquid level meter, testing of circuit component parameters, and testing of main technical indicators of the liquid level meter. Voltage and current testing are commonly used. Power-off testing refers to testing of relevant circuits, devices, components, and insulation resistance of the liquid level meter. By comparing the test data with normal data, it is possible to identify whether the liquid level meter has a fault and the scope of the fault.

3. Panel Compression Method: The panel compression method utilizes the switches, knobs, jacks, buttons, and indicator devices on the float level gauge panel to perform fault compression. It is a commonly used external compression fault method for determining fault symptoms and identifying faulty components. However, since the level gauge panel may not be fully equipped or may not control all the components that determine faults, it is sometimes necessary to cooperate with other methods to fully confirm the scope of the fault. Therefore, in general, the panel compression method is an effective auxiliary method.