For any tank containing fluids, it is necessary to monitor the level of the liquid inside the tank. This is essential for refilling, to prevent overflow etc. Various types of touch and non-touch methods are available for the same. Various types of such tanks are water tanks, bulk storage tanks, petroleum tanks, oil tanks, sewage tanks etc. Many of the latest models of liquid level sensors come as a separate liquid level transmitter, which transmits the data and a receiver for receiving and processing the data.
Floats with contacts for signals
Floats are one the oldest form of liquid level measurement. In this case, there will be an air-filled ball connected to a lever. When the liquid reaches this level, the float rises along with the liquid and an electrical switch will be activated. The material of the float will be plastic or stainless steel based on the application.
Ultrasonic level sensor measurement
Ultrasonic level sensor are also known as ultrasound level gauges. This is one of the most common types available nowadays. This is a measurement by a non-touch method. The ultrasonic sensor transmitter is fitted at the top of the tank. It sends frequent signals to the bottom of the tank. The ultrasound signals bounce back at the top of the liquid. The time taken by the ultrasound signals to reach back at the transmitter is determined by the transmitter. This gives the exact measurement of the level of the liquid. The reading is then displayed on the display. If the unit has a transmitter, the data is transmitted for further processing such as to an automation system. These are also called laser beam liquid level transmitters. However, the laser beam is not used for measurement.
Radio wave liquid level indicators
These are similar to ultrasound level indicators, but use radio waves instead of ultrasound signals. The transmitter is fixed at the top of the tank. The bounced signals give a distance from the top of the tank to the top of the liquid level.
Microwave liquid level transmitters
Microwave level transmitters are also exactly similar in operation. In this method, the level measurement is done using microwave signals.
Hydrostatic liquid level switch
Hydrostatic liquid measurement works by measuring the pressure applied by the liquid column. The pressure on the sensor will be directly proportional to the height of the liquid. Hence by measuring the pressure, the height of the liquid can be measured.
Capacitance liquid level measurement sensor
In this method, the capacitance is measured which is directly linked to the level of liquid. A certain level of capacitance is developed between the probe and wall of the tank. Depending on the level of the liquid, the measured capacitance varies. We can derive the height of the liquid from this capacitance value.
Water level monitors
Water level sensors are the most common type of liquid level transmitters. For water level monitoring, any of the above methods can be used. However, most commonly used methods are ultrasound measurement and float indicators. The float level switch can only provide a signal whether the water has reached the level or not. It cannot give an indication if the water level somewhere in the middle. A float switch is the cheapest form of switch available for tanks. Stainless Steel floats are available for corrosive liquid tanks. In this case, the material and the stem of the float will be stainless steel.
Silo monitoring systems
Silos are tanks generally used to store food grains, food grade oil, flour etc. However, it can be used to store any items such as powder, cement etc. Generally, food grade Silos are made out of stainless steel. We can monitor the level of the content inside a silo by ultrasound level indicators.
Integration of liquid level sensors into Automation systems
The sensors are capable of communicating through protocols such Modbus, BACnet, etc. This way it can be integrated into an automation system, SCADA, PLC Panel etc. Our automation team will be able to develop a suitable solution for the same.
Phone call, SMS alert for liquid level indicators
For critical applications, you can connect an auxiliary phone call alert system. Eg. In a critical tank, you may monitor the level of the liquid at two heights. As the liquid reaches the first level, if the motor is not shut off automatically, the liquid rises to the second level of alert. Once it reaches this level, a phone call system will be activated. This system will make phone calls to 8 operators and simultaneously SMS also will be sent. Once the operator picks up the phone, it will deliver a custom recorded voice message. Eg. “The water level in tank 3 has reached critical levels”.