Design Of A Liquid Level Control System

To demonstrate your research skills and understanding, the report must draw upon relevant sources like journals, books or reputable trade publications in analysing the project. You must also present the case study in terms of the above two lifecycle phases and evaluate the proposed conceptual design against the identified needs / requirements. 

Importance of a liquid level control system

Water tanks form major source of water in industries, farms, or hotels especially in case where the piped water is not sufficient or reliable. The water tanks provides a backup source of water in these places and the water is normally pumped in these water tanks by these of electric pump. When the tank is almost used, then the electric pump is switched on and the water is pumped to the tank, while when the water in the tank is almost full, then the electric pump is switched off by physically observing the level of water in the tank. This research paper seeks to design a liquid level control system which has the ability to regulate the level of water or any other liquid in the tank through the incorporation of a mechanism of feedback control.

In this system of feedback control, there is the comparison of the results of output before a suitable corrective mechanism is taken. In this feedback control system, there is usually a command issued to the system with an assumption that the mechanism will function properly. Any system of control can be classified as sequential, continuous, or discrete control systems. A liquid level control system is very important since it helps in the prevention of losses that occur due to overfilling of the liquid tank depending on the liquid that is being pumped by the electric pump to the tank. There are cases where the type of liquid being pumped into the tank is of high value and this means that the company will incur high losses in case of overflow (Bakshi, 2010).

This design of a liquid level controller system is a very significant control system that will be used in controlling the pumping of any type of liquid in a tank situated above the ground. Controlling the pumping of liquid by an electric pump will prevent wastage caused by overfilling of the tank during the process of pumping. The most common way of checking if the liquid being pumped into the tank is almost full is through physically and constantly checking the level of liquid in the tank. This normally results in a lot of time wastage since the individual must constantly be visiting the tank to check the level of water in the tank so as to be ready to turn the electric pump off in case the liquid is almost filling the tank (Chau, 2012).

Feedback control in liquid level control systems

There are also cases where the liquid being pumped into the tank may have some health effect when inhaled by an individual. The observer will be required to constantly check the level of liquid that has been the pump in the tank and also not the duration it will take before the tank is filled. Opening the tank for the purpose of observation can be dangerous to the people working around the tank. The liquid level controller system will ensure that no person will get into contact with the liquid being pumped since this control system can automatically regulate the level of liquid being pumped in the tank by an electric pump through the incorporation of a feedback control (Cho, 2010).

The liquid level controller system is an important control system in the prevention of losses that may occur as a result of overfilling of the liquid in the tank depending on the type of liquid that is being pumped into the tank by the electric pump. Overfilling of the tank resulting in the liquid overflowing from the tank can also be dangerous if the liquid is flammable or harmful to human health since their spillage may pose a serious danger to the employees working of the company and also to the company as a whole. The dangers, time wastage, and health effects caused by overfilling of any liquid being pumped to the pump by an electric pump is the major reason why the design of a liquid level controller system is significant for both households and commercial purposes.  This research paper seeks to come up with a conceptual design of a liquid level controller system which can be used for both small-scale and also for commercial purposes (Dorf, 2009).

Any control system can either be an open loop or a closed loop control system. In the control loop system, there is a comparison of the results or output of the system before an appropriate corrective action is taken to rectify the situation. In the open loop control systems, a command is issued to the control system with an assumption that the system will function properly. A control system can be classified into the sequential, continuous, and discrete control system. A sequential control system may cause a machine or system to go through a functionality series like the elimination of milking machine from a can after there is no more milk left in the parlour, and then open the gate to allow the cow walk out (Gopal, 2009).

Hardware components in the design of a liquid level control system

This paper focuses on the design and implementation of a simple and effective proposal of a feedback regulator that can be used in water level sensing and control. The two traditional methods of finding out the level of liquid in a tank enclosed can be though tapping the sides of the tank until sudden changes in the sound produced during tapping are noted or through removing the lead of the tank and then inserting a measuring stick to determine the level of liquid in the tank. There is a need of designing a more advanced method of sensing the liquid level in the tank by the application of electrical circuit established for such applications. Variety of circuits can be established and deployed for water sensing based on integrated circuit technology and the signal output from the sensor of water (Ibrahim, 2013).

Many modern processes in industrial, commercial, and medical applications do not require advance temperature ranges despite the pressure sensor being sensitive to temperature. The design illustrates a cost-effective, low-power, liquid-level control, and delivery system based on the system of data acquisition which utilizes a compensated silicon pressure sensor and high-precision delta-sigma. In the automated control system design, a closed-loop system is used which applies the liquid level in the tank as the input to control the power supply to the electric pump. Therefore, the output is expected to be a discrete variable actuated by the application of an electrical circuitry (Langari, 2012).

The liquid level is expected to be scrutinized by the application of two electronic sensors situated at an appropriate location to detect low and high values of liquid levels. The output signal is expected to be fed into the circuit where it is transduced into an ON or OFF signal which regulates the power supply to the pump. The major advantaged of this proposed design is that it is not restricted to the size and nature of the tank with liquid. Therefore, any tank with liquid can be converted into a control tank by coupling the circuit and including the regulator sensor inside the tank (Mohd, 2011).

This section evaluates the hardware components and the software components required during the design of a liquid level controller system. The software components that can be used in the design of a liquid level controller system include MC Programming language and Arduino compiler. The hardware components that can be used in designing a liquid level controller system include relay, lamp, diodes, ultrasonic module, transformer, crystal display, holder, LED, voltage regulator, transistor, MOSFET, and the microcontroller unit. Arduino compiler is a board with many microprocessors and controllers and also sets of digital and analogue output and input pins that may be coupled with many expansion boards and circuits (Mutambara, 2011).

Software components in the design of a liquid level control system

The PC is used in monitoring and modification of the feedback signal from the sensor of pressure and transmits a control signal for the selection of three diverse modes of operation and allow the input liquid level set point, sample time, and values of Arduino compiler. The ultrasonic module is applied during turning ON or OFF the motor or pump when there is a drop in the level of liquid or water from the desired level. The module is to be incorporated with an ultrasonic transmitter and an ultrasonic receiver. The ultrasonic transmitter transmits the high-frequency sound pulse and this pulse is reflected after the collision of the desired object (Nagrath, 2009). 

A Programmable Logic Controller is also one of the major components used when designing a liquid level controller system which is ruggedized for the control of any type of processes like assembly lines and robotic device. Some of the features of the programmable logic controller are that it is more tolerant to severe conditions of the environment such as dust, moisture, heat, and cold while issuing intensive input/output to connect to sensors and actuators and also they are anticipated for an explicit function. The PLC input includes digital parameters like temperature and pressure (Vasistha, 2014). 

The other major components needed when designing the liquid level controller are the water tank and the electric pump (Patrick, 2012). The tank that will be used in the experimentation of the designed liquid level controller system should be fabricated by the application of a galvanized iron sheet which is folded and welded into the cylindrical shape desired. There should also be a provision for both inlet and outlet pipes on the water tank. The diode type used in the design is the blocking diode which is applied in ensuring that the transformer is safe and also during blocking of the reverse polarity current. The voltage regulator is applied during the regulation of the 12V direct current into 5V direct current supply (Varmah, 2010).

The transistor used in this design function as an inverter such that during ON mode, the transistors are expected to deliver low output voltage while during OFF mode, they deliver a high output voltage (Razeni, 2013). The power supply of 5V is to be supplied from the transformer which is coupled to the bridge rectifier to be converted from AC to DC and also connecting a voltage regulator for a constant supply of 5V direct current. A 5V DC supply should be directed to the water tank positioned with 8 sensor wires such that a single wire is connected with a power supply of 5V is connected with the transistors (Syauqi, 2010).

Operation and evaluation of a liquid level control system

The liquid level controller system operation can be evaluated easily after coupling the electrical components like microcontroller, sensors, and wires.

When there is still no water in the water tank, there will be no path between the eight designated probes and the other probe is coupled with the power supply of 5V. The microcontroller is expected to use 0 to 2V for a high region and 3V to 5V for a low region. When the water starts to flow in the tank, the path is expected to be to be noted between the sensor probe and the corresponding transistor attains enough biasing at the transistor base. The water level is anticipated to be 7^th level then the intermittent lamp will be triggered which informs the observer that the tank will not be filled any time from then (Smith, 2012). The microcontroller is set as a priority encoder which helps in detection of the optimal input priority and shows the steady level of the seven sector display. When the tank is almost full, the apex of the probe attains the pathway through water and the corresponding transistor will enter into the pathway with the output set to the microcontroller. This will trigger the nonstop lamp to notify the operator that the tank is almost full and also turn the motor to stop the process of pumping water into the tank (Syauqi, 2010).

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