Tank level alarms are devices that are used to monitor the liquid level in a tank. They function by detecting the level of liquid in a tank and activating an alarm or sending a signal to a control panel when the liquid reaches a certain point.

There are several different types of tank level alarms, each with its own unique method of operation.

1. Float switch alarms use a float switch that is attached to a buoyant object that rises and falls with the liquid level in the tank. When the liquid level reaches a certain point, the float switch activates an alarm or sends a signal to a control panel.
2. Ultrasonic level alarms use ultrasonic technology to measure the distance between the sensor and the liquid surface. The sensor emits a high-frequency sound wave that travels through the air and reflects off the liquid surface. The sensor then measures the time it takes for the sound wave to return to the sensor, which is used to calculate the distance to the liquid surface.
3. Radar level alarms use radar technology to measure the level of the liquid in a tank. The radar sensor emits a radio frequency signal that bounces off the liquid surface and returns to the sensor. The sensor then uses the time it takes for the signal to return to calculate the distance to the liquid surface.
4. Hydrostatic level alarms use a pressure sensor to measure the weight of the liquid in the tank. The pressure sensor is located at the bottom of the tank and measures the pressure caused by the weight of the liquid.
5. Magnetic level indicator use a magnetic float that is held in place by a magnetic field. The magnetic float moves along with the liquid level, which causes the movement of an indicator that can be read to know the level of the liquid in the tank.
6. Sight Glass Level Alarm use a transparent window that allows the operator to see the liquid level in the tank. They are used in conjunction with a level switch that activates an alarm when the liquid reaches a certain level.

In conclusion, Tank level alarms function by detecting the level of liquid in a tank and activating an alarm or sending a signal to a control panel when the liquid reaches a certain point. There are several different types of tank level alarms, each with its own unique method of operation such as float switch, ultrasonic, radar, hydrostatic, magnetic level indicator and sight glass level alarms. Each of these alarms have their own advantages and disadvantages, you have to select the one that best fits your needs.