ABSTRACT The level measurement and calibration experiment were conducted to fulfil the objective which to analyse the relationship between the levels and their differential percentage by using pressure device. The experiment was dividing into 4 part with variable for open and closed tank by using heater or not. The general setup procedure being followed, and the experiment was using sight glass device to record the actual level. All four experiment showed the actual value LG is lower than actual value LI. The difference between the LG and LI values are very small. It is important for the values to be as close to the suggested value to reduce the occurrence of error while carrying out a reaction. There are several recommendations for this experiment in term of safety. The preparation to analyse the equipment and understanding the usage of every valve before its running are compulsory. Level measurement and calibration is essential in process industry as it is very important to keep track of the amount of substances or reactants in a reactor. This is because malfunction in the level measurement might cause unfortunate accidents as some substance that are being handled might be very harmful and needs a special care. Figure 1: the sight glass device used in level measurement and calibration experiment. OBJECTIVES The level measurement and calibration experiment objectives are: • To carry out the level measurement and calibration experiment systematically. • To study the level measurement using Pressure device • To investigate the relationship between level and their differential percentages. INTRODUCTION AND THEORY Level measurement is the measure of solid height or fluid within a tank or vessel. These measurements are important to run a plant and required by many industrial process. Some instruments that are used in the process are displacement type, level gauges, float type, echo type, hydrostatic pressure measurement and displacement type. The use of level measurement is to monitor, control process or operation and carry out some analysis to prove the accuracy of theories (Ghosh, 2012). Level measurement can be divided into two types of level measurement comparison. The first one is contact and the second one is noncontact shown in figure 1. The objective of this experiment is to identify the important component for level measurement in the instrumentation, to carry out the start-up procedure systematically, to study the level measurement using related device. This is done by comparing between different level measurements from 700 mm down to 300 mm and to study the level measurements in open and closed tank, to investigate the relationship between level and their differential percentage. Calibration very important in this experiment. It is a measurement that consist of two parts, a correction. This is to adjust the measured parameter to the normal value and the second part is to measure on how wrong the correction could be. (Bently, 1998). It is very crucial because for example it the measurement was too high, pumping of material will occurs some difficulty and might even damage due to overflows and dangerously high pressure. Through the experiment the process involve was measuring different levels of water with or without the function of heater within closed or open tank. The variable that include in this experiment is suggested level (mm), actual level LG (mm) that can be obtained by the sight glass and actual level from the level indicator at the front panel (LI). The formula used to measure level of 700 mm to 300 mm is Deviation = [LG –LI] mm The machine contains several components that its used in order to aid the flow of the process. One of them is valve for example top vent, by pass valve, drain valve, pump discharge valve. The function of this device is to maintain direct control of moving fluid and gas by open and closed the device. Secondly is overflow valve. Since in industry of plumbing, pipe and electricity it has been issue on safety device that’s pressure building up and by the help of sensor it can alert the operator regarding the issue. Same goes to the valve that’s function by sensing the pressure up pipe. METHODOLOGY The experiment was run by 4 major different set up. Firstly, Tank T1 as OPEN Tank, Heater OFF, secondly, Tank T1 as CLOSED Tank, Heater OFF next, Tank T1 as OPEN Tank, Heater ON and lastly, Tank T1 as CLOSED Tank, Heater ON. The plant started up procedure was run by filled the water in Tank T2 up to its overflow level. At the same time, the drain valve needs to fully close. At the front panel, the heater and pump were off. Then, the main power supply located at the front panel was switched on. The pump suction valve and all pump discharge valves were fully open. The pump by-pass valve (BV) was opened one turn before starting the pump. After pump start-up, the BV was fully closed. First experiment for tank T1, the top vent and overflow manual valves were fully opened. Then the pump was started by pressing the green pushbutton at the front panel. The flowrate was adjusted by using Variable Area Flowmeter (FI) to about 2.5m3/hr. The manual discharge gate valve at tank T1 was closed and the pump was stopped. The bottom globe valve of tank T1 was opened to allow the water in tank T1 to flow into tank T2 until the level at LG reads about 700mm. Then, the bottom globe valve was closed. The reading was recorded 2 set in the Table 1. The measurement level was continued from 600 mm until 300 mm. These procedures basically are same for second experiment. The different just at the beginning which for Tank T1 as CLOSED Tank, Heater OFF, fully CLOSE the vent, overflow, bottom gate valve and globe valves of tank T1. For third and fourth experiment, the heater was switched on and the procedures were repeated for T1 opened and closed tank respectively. After all the experiments were done, the shutdown procedure was run by switched off the heater. The overflow manual valve and the top vent valve of tank T1 were fully opened. The water in tank T1 was drained out by opening the manual discharge valve i.e. the gate valve. After that, fully close both the gate valve and globe valve. The water in tank T2 was drained out by opening its manual drain valve. Lastly, the main power supply was switched off. DISCUSSIONS The title of this experiment is level measurement and calibration. In this experiment, we measured the level in an open and closed tank with heat on and heat off. Level measurement is important in the process control industry as the need to measure the level of a process material in a container. Level measurement can be a determining factor in both profit margins and safety. For each section of the experiment, two sets of readings were taken and then the average was calculated. This is done to obtain a more precise value. For the open tank with heater off situation, as we can see from the bar graph plotted the level gauge (LG) and the level indicator (LI) is reducing as suggested level set is reducing. This shows that the level measurement of the tank is effective. For the second case, which is the closed tank with heater on the LG and LI value is decreasing with the reduce in the suggested level of liquid in the tank. For the third case, close tank with heater on the LG and LI value is subsequently decreasing with the suggested value as well. Lastly for the fourth scenario where it’s an open tank with heater off the LG and LI is also decreasing with suggested value. For all these values, the difference between the LG and LI values are very small. It is important for the values to be as close to the suggested value to reduce the occurrence of error while carrying out a reaction. Level measurement and calibration is essential in process industry as it is very important to keep track of the amount of substances or reactants in a reactor. This is because malfunction in the level measurement might cause unfortunate accidents as some substance that are being handled might be very harmful and needs a special care. CONCLUSIONS AND RECOMMENDATIONS This level measurement and calibration experiment involved four sections, which the level was measured in an open and closed tank with heat on and heat off. For each section, two sets of reading were taken to obtain a precise value and the average was calculated. For first section, tank T1 was opened and heater off, the bar graph plotted shows the level gauge (LG) and the level indicator (LI) is reducing as suggested level set is reducing. Next, for the closed tank and heater on, the value is decreases as the suggested level of the liquid was reduced. When the tank was closed with the heater on, the result shows that the value of both LG and LI is decreasing as the suggested value reduced. For the last section, where the tank was opened with heater off, value of LG and LI also decreases as well as suggested level. To conclude, the difference between all the LG and LI values are very small and it is very important for the values to be as closed to the suggested value to avoid any errors. There are a few precautions should be taken to obtain more precise results. The first one is, to make the experiment run smoothly, the level of the water in tank T2 should be maintained to avoid the shutting off the heaters and the pump. Next, when taking the reading for the level indicator (LI), it is needed to make sure that students wait for the reading to be constant before noting down the value. In addition, it is compulsory to know which valve needed to be open or close so that there are no errors occur. Lastly, before starting the experiment, make sure all the equipment, switches, valves that will be used are working properly to avoid any interruption during the experiment. TUTORIAL 1. Level is measured in many of the processes in the industry. List and explain the most common reasons for measuring level. a. To keep track the liquid level. The most common device that is use for monitoring the level measurement is float level switch. This device is operated using buoyancy principle and it is float and contain powerful and permanent magnets. When put in vertically it provide the accuracy and reading of the level measurement and all the level point are being monitored. b. To monitor and control the level of measurement for example rotary level indicator that are used for particulate materials such as powder, plastic, wood dust, cement and sand. It is located at above the material or to the side to measure high or low level control. c. For ultrasonic level measurement. In this measurement unit, it consists of piezoelectric crystal stored in the transducer. The function of transducer is to convert electrical sign to sound energy. It is use for measure a hot, boiling and corrosive liquid. The range frequency that is use normally 40-200 KHz. 2. Name the two methods of level measurement used in the experiment. a. Direct method which is not required compensation for changes level causes by temperature change. b. Indirect method the compensate due to sensitive on specific gravity and temperature. 3. How the depth of a liquid does correspond to changes in liquid pressure? Can a pressure transmitter be used to measure level? All things on Earth include water have gravity which mean the body and things are pulled down by the force. The pressure of water is the effect of weight at the water the upside push downward on water below. For example, as we go deeper into the sea there is a lot water exists above, therefor a higher weight pushing down. As for the result, the deeper the water, the higher the pressure will be. Pressure transmitter can be used to measure level because the function of this device is to measure the pressure inside the machinery. One of the functions is to give a warning before a catastrophe happen. 4. The differential pressure transmitter is used to measure level in an open tank or closed tank system. Discuss how this is done. The differential pressure is the differential between high pressure and low pressure. The high pressure for open tank was used a atmospheric pressure meanwhile, closed tank was used gas pressure inside the tank because the tank was fully closed. 5. Discuss briefly the possible errors affecting the accuracy in pressure / level measurement as observed in the experiment. The first one is when taking the result. The student does not focus on the task given for example taking the reading of measurement and actual level. This may affect the result of the experiment. Secondly, before the experiment the student also need to familiar with valve, pump and all machine part because if not, a few miss step and wrong open and closed valve might occur. 6. What are the main objectives of a wet lag calibration? Throughout the process of using differential pressure transmitter, the fluid can evaporate and condensed. The main objective of the wet leg measurement is to measure the level of the phase in gas or liquid. So, the condensate fluid does not affect the reading by giving the false indication. REFERENCES Bently, E. R. (1998). Handbook of Temperature Measurement Volume 3. The Theory and Practice of Thermoelectric Thermometry. 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