Float switch for water level control: principle of work, advantages, installation
There are a large number of different devices to ensure convenient control of the pumps, among which the float became widespread. Among the features of this device should be noted that, that it can simultaneously perform the function of a water level sensor and at the same time an executive control of the pump. Their location is storage tanks, tanks, tanks, as well as wells, etc..
The space of one such tank is enough to accommodate several floats, and they can solve different problems:
- Monitor the operation of the main pump;
- Ensure efficient operation of the auxiliary pump;
- Act as an emergency level sensor;
- Use as an overflow sensor.
With similar devices to control the water level, which are used in these systems, it is possible to protect the pumping device from transition to the "dry running" mode. Also in case of filling of various tanks this element allows to protect them from overflow.
There are several types of floats for pumps:
- easy;
- heavy.
The first became widespread in water supply and sewerage systems. The latter are mostly used in drainage, fecal and rainwater runoff. In stores, these devices are offered with a cable length 2, 3, 5 and 10 meters.
Device and design
Such an element, as a float switch to control the water level has a floating plastic housing. It has an electric switch and a lever, which allows you to transfer the contacts of the switch. Also in the composition is a steel ball, which in case of change of position of a float corrects a position and the lever. A cable is connected to the switch, consisting of three wires: the first is common, and the others are connected to the normally closed and normally open contact of the switch.
The circuit closure is provided by the black and blue wires at that moment, when the swimsuit is in the lower position. In case of its transfer to the top position black and brown wires will already act as closing contacts.. Insulation of that wire is a must, which does not connect the device. It is important to take care of that, that the supply cable has moisture-proof properties, at the same time the design of a plastic box should differ in tightness. A mechanical seal is used to seal the cable outlet, it also has a special device, which allows to remove mechanical stresses in a cable.
Inside the insulated cavity of the cable entry is a polymer resin, which protects against water ingress. It is with the chemical properties and heat resistance of the housing and cable sheath, which are made using thermoplastic rubber, the ability of the float switch to tolerate the interaction with alcohols is related, uric acid, fecal waters, gasoline and other aggressive substances.
Due to the absence of pores on the surface of the plastic housing, it does not appear contaminated. At the same time, this feature ensures the sliding of sand, paper and other solids, against which the float switch retains its floating properties.
Characteristics of the sensor for control of water level:
- Mains voltage, V - 220 ± 10%;
- Maximum switched current, A:
- 8And - for reactive loading (pumps, fans, compressors, etc.. P.);
- 10And - for active loading (starters, switches, shadows, lamps, etc.. P.);
- Operating temperature range: 0-60 ° C;
- Protection: IP 68.
advantages
Among all the benefits, which has a float switch to control the water level, first of all it is necessary to allocate that, that it is able to perform the function of a conventional sensor to determine the water level in the tanks. And he successfully performs this task, even though, what the capacity is used for and for what purpose it is. However, this water level monitor is able to help make the operation of pumping equipment more convenient. This device simplifies the control of industrial functions, household water supply systems.
In some cases, it can be used to successfully drain fluid. Also the float switch for control of level of water can be a part of the equipment at construction of sewer communications. Ease of operation and high efficiency of its application and have provided the float switch widespread in the most various systems, where there is a problem of water control.
It is worth noting, that the ability to provide reliable protection for pumping systems in dry mode is not the only positive qualities of such devices. However, with their help you can avoid the situation, when there is an overflow of water in the tanks.
installation
One of several methods can be used to install float switches. Before installing this device, make sure, that is the nominal current, used to operate the pump, less than the maximum allowable current value, which is given in the specifications for this type of float. Among the known methods of mounting a float switch to control the water level, the easiest to implement is its placement in the tank, which involves the use of a float with a cable and a special sinker, which is included with this device.
With this installation option, the sinker must be secured to the cable, and then experimentally calculate the free length of the float. Using a latch, the sinker must be attached to the cable. After that, the cable must be firmly fixed on the outside of the tank. Then proceed to the connection of the float switch to the pump. After that, the device can be used for its intended purpose.
Option to install a float for pumps, which involves the use of cable, that fails, can be applied only in a situation, when there is no risk of the main device catching or hanging in the tank itself and when only one float is placed in it.
In some situations, it may be decided to install several floats to control the water level. In this case, their installation is carried out on a special rod. As the last fragments of a plastic pipe are most often used, which must be firmly fixed in the tank. After that, floats are installed on the pipe, and they must be set correctly, adjust and spread along the length of the rod with that calculation, so that they do not create difficulties for each other to work properly.
Cable routing, coming from float switches, to the bar is carried out using clamps. When choosing the number of float switches should pay attention to the number of pumps or the type and number of protective devices and control panels used. In some situations, the problem of ensuring the reliable operation of float switches can be solved by using several rods.
When determining the installation scheme of float switches, their number and location must always take into account the specifics of the place of their installation or focus on the project.
The principle of operation of the float for pumps
Such devices, as float switches can provide different schemes of their use, and this affects their principle of operation.
Water supply system, filling and emptying the tank of the tank
At such scheme of work at the moment of ascent the float de-energizes the pump, which supplies water to the tank. The signal to turn on will come only when it reaches the bottom. This situation occurs only when the tank is empty.
The float gives a signal to turn on the automatic water supply station at the time of its presence on the surface. Disconnection of the station can occur only when the float is immersed in the bottom with an empty tank.
From the float received a signal to close the valve or latch with a servo at the time of its rise to the surface. Opening of the valve or latch will happen only the moment of its immersion to a bottom at empty capacity.
The operation of the float can only be to notify the control room or operator at the time of its rise to the surface, which will correspond to the filling of the tank. Information about the lack of water will come at that time, when the float reaches the bottom.
sewer system
The float pumping equipment will be switched on only when the main control unit is raised.. The pump set is switched on when the control unit is immersed in the bottom.
One float can simultaneously serve two pumping units: the first apparatus can supply water to the tank provided, that the float is in the lower position. At this point, the other pump is not running. When the float is in the upper position, the second pump is switched on, whose task is to pump water out of the tank. At this time the pump, which supplies water to the tank, is in an inactive state. Despite its simplicity, the above scheme of application of the float switch is not effective enough, as this does not preclude difficulties with regular water delivery at those times, when the tank is filled.
Operation, maintenance and repair
It is possible to provide long-term operation of floats for pumps only in that case, if the rules of their use are not violated. In the situation, when the float switch is part of the water supply and drainage system, you can not waste time and effort on its maintenance. If this device monitors the operation of fecal or sewage pits, it is recommended, at least, once a month to clean the float and pump from dirt, using a stream of water, supplied under pressure.
This procedure will prevent the float from sticking or sticking to the pump or pressure pipe. Float switch, which due to certain circumstances is unable to perform its primary task, there is an inoperability, therefore in such situations its replacement is carried out. This work should be performed by service center specialists.
conclusion
In situations, when there is a need to ensure the supply of drinking water to the house or the removal of contaminated sewage, have to be used in combination with pumping equipment and special devices. Among them, a float switch is quite effective. The benefit of its use is, that it controls the amount of liquid in the tank, and, focusing on this, determines the mode of operation of the pump set.
This device avoids the transition of the pump to "dry run" mode., which has a positive effect on its service life. In addition, it saves a lot of electricity, as the float switch allows to start the pump only when necessary.
