Banner Sensors – The difference between a level sensor and a level switch, a level controller, a level transmitter, and a level gauge

Liquid level sensors

A liquid level sensor is a common sensor that measures the position of a liquid level, and it is an output that converts the height of the level into an electrical signal. The liquid level sensor is a module circuit, which has the advantages of acid resistance, moisture resistance, shock resistance, corrosion resistance, etc., and contains a constant current feedback circuit and an internal protection circuit inside the circuit, which can make the maximum output current not exceed 28mA, so that the power supply can be reliably protected and the secondary instrument is not damaged. Therefore, liquid level sensors are widely used in medical, chemical, automobile, home appliances and other industries, such as water pumps, toilets, bathtubs, water heaters, washing machines, coffee machines, milk brewers, electric steamers, aromatherapy machines, face sprayers, power batteries, medical equipment, etc. In general, it is used in electrical appliances and equipment that require water level control.

The common types of liquid level sensors are: radar liquid level sensors; Liquid float type level sensor; Hydrostatic level sensor; capacitive level sensors; Photoelectric liquid level sensor; Ultrasonic level sensor.

Level switches

A level switch is a switch used to control the position of liquid. When the measured liquid medium is up to a certain indication position, the liquid level switch will output an alarm signal according to its working principle, so as to stop continuing to convey the liquid medium; When the measured liquid medium is lower than a certain set position, the liquid level switch will also output an alarm signal to remind the headquarters to open the gate and start to convey the liquid.

For example, if the water level of the water tank is full, the float or float touches the switch to turn on the switch and send out an audio signal or control signal, which is a switching signal. If the sensor is used, the sensor can send out an electrical signal amount that cannot be passed according to the change of water level, such as the output is a standard signal 4mA · - 20mA, when the water level is the lowest output 4mA current, when the water is full output 20mA current.

Difference: The principle of the level switch and the level sensor is the same. However, the liquid level switch is a switching control circuit, and the liquid level sensor is a circuit element equivalent to the voltage conversion and current transformation. In other words, if you want to measure when the liquid has reached the level, use the level switch, and if you want to accurately measure the height of the liquid level, use the level sensor. However, the two can sometimes be used together.

Level controller

The liquid level controller, also known as the water level switch, is mainly used to control the liquid level switch, which is mainly divided into contact and non-contact liquid level switch. Its working principle is to control the high and low liquid level through mechanical or electronic methods, and can control solenoid valves, water pumps, etc., so as to achieve semi-automatic or full automation.

It is worth noting that the float of the level controller is susceptible to external debris affecting its stability, especially the fibrous debris winding and there are mistakes, and more than one should not be used in the same small tank, otherwise it will be entangled. The service life is relatively short, and most of them are directly connected to 220V, which has certain potential safety hazards. Therefore, the power cord of the float switch is a complete part of this device, once the wire is found to be damaged, the device should be replaced, and the wire is not allowed to be repaired.

Difference: There is a difference between the liquid level sensor and the liquid level controller, the liquid level sensor is only a single product, a product to achieve the effect, and the liquid level controller needs to borrow the signal sent by the sensor to control the start and stop of other equipment, the two should be connected together, the sensor provides a signal to the controller, and then controls the work of the equipment. It's a tandem working relationship.

Level transmitters

The liquid level transmitter is the extension and development of pressure transmitter technology, according to the principle that the pressure generated by the liquid with different specific gravity at different heights has a linear relationship, such as when the two pressures of the measured medium are passed into the high and low pressure chambers, acting on the isolation diaphragm on both sides of the δ element (i.e., the sensitive element), and the filling liquid in the isolation sheet and the element is transmitted to both sides of the measuring diaphragm, so as to realize the accurate measurement and transmission of the volume, liquid height and weight of water, oil and paste.

Difference: Liquid level sensor, emphasizing the detection of liquid level signals. For example, the float in the float level transmitter is the so-called "level sensor", which is used to float with the liquid level and use the up and down distance of the float to indicate the liquid level.

The liquid level transmitter emphasizes "change" and "send". For example, when the float moves up and down with the liquid level, an electrical signal of position is generated in a metal pipe, and this process is called "change". And this electrical signal is often not standardized in size, and it cannot even be used for later circuits. For this reason, a circuit is installed near the tube, the purpose of which is to convert this non-standard electrical signal into a standardized electrical signal (such as 4-20MA, 0-10V, etc.), which can be output to other instruments or devices for display or control. This device is called a "level transmitter".

Level gauge

The level of the liquid medium in the container is called the liquid level, and the instrument that measures the liquid level is called the liquid level gauge. The liquid level gauge is a kind of instrument specially used to measure the high and low positions of the liquid level. The position of the measured liquid medium in the container (including tanks, storage tanks, and spherical tanks) is called the liquid level, and the instrument that measures the liquid level is called the "level gauge". Compared to the level switch, the working principle of the level gauge is relatively simple. The level gauge includes a tuning fork level gauge, a float level gauge, a magnetic flap level gauge, an ultrasonic level gauge, a radar level gauge and so on.

Banner Sensors – The difference between a level sensor and a level switch, a level controller, a level transmitter, and a level gauge

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