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Well, students we have already discussed in the my previous lecture about these sprayers and dusters. Now, we will go into some more details of how to design and how to select plant protection equipment, keeping in view the requirement of the crop, requirement of the situation and the other parameters which are there at the hand of the designer So, see the chemical tank, as I said this is the first item which is to be there, now how what should be the capacity of this? How do you get the capacity of this? Will be it will depend on certain aspects whether you are talking of the power source? What is the power source? If the power source is manual then what will happen? If the power source is mechanical then what will happen and what should be size? This is what is important Now, how do you get this capacity? See the actual capacity generally 5 to 15 percent more than the required capacity to ensure there is always liquid for agitation. Now, you see sometimes when the agitator is there it will keep that the liquid which we have created is in the right composition. It should not be that the particles settle down and then water is there on the top. So, there should be the agitation should be sufficient so, in order that this happens actual capacity should be 10 to 15 or 5 to 15 percent more now we need to know what is the capacity of the tank? So, for knowing the capacity tank it is very simple it you do not require such big mechanics for that, you should know what is the length of the plot that you have at your disposal and what is the width of coverage which you want to do. So, if you know these two things the application rate is known to you because depending upon the inter station or depending upon the earlier data that you have you will utilize this And once this is there you can get this formula This is very simple you can just multiply this should be in the area this is the application rate in liquid I mean liters per hectare So, with this area I got you are getting actually liters or, you can get into meter cube, here it will be in meter cube because we have given the units accordingly and that is why state 10-7 is so, the capacity of the tank can we know Now, what is the material of the tank? See, you know that these materials could be corrosive So, it will finish, virtually the tank will not last long so, we have to away careful about the material of construction on the tank which is thought off Generally, the aluminium is one which is fair enough then galvanized steel which is used, stainless steel and polyethylene plastics are commonly used for construction of sprayer tanks. Yes, these are ones which are used and we find that these plastics are coming up in a big way particularly with regard to the weight as well as non-corrosive So, these are ones which are coming up you do require a technology for creating those big tanks of plastic and all that, but that now very much in use and various types all in fact, all the sprayers which might have seen or all use of plastics. Hardly anybody uses aluminium or galvanized all, but these are the materials one can use depending upon the situation depending upon what you wants so, these are the materials And you can see that we have shown you the is one which is there with us at IIT, Kharagpur which is of course, procured one, but then this is the one which we have for the for orchards we are trying this testing is for orchards So, and upon the capacity generally or the types of for sprayers the capacity generally for hand operated small sprayers could be 1 liter, could be 14 liter, knapsack sprayers are 15 liters, 14 liters, 16 liters sometime depending on the size and the tractor operated once a 400 to 2500 liter capacity Now, because once it is in the power source which is very high in that case then you can use this big ones and ultimately you will be in a position to minimize the time for completing this particular operations so, that is very important Well, the heart of this particular this sprayer is the pump here because, these the one which is in fact, delivering the energy for creating the droplet us. Now, let us have a look at these what are the different types of the pumps which are used and how they are constructed

what is the pressure which is required and all these things. So, if generally you know that when you are talking of high pressure pumps, generally these high pressure pumps are piston pumps or plunger pumps or diaphragm pumps or rotary pumps Now, this the pressure you can see we have talked of this pressure, but then it is worth mentioning here also the operating pressure is varying from 4.1 to 5.5 MegaPascal or 600 to 800 PSI, then the flow rate is about 75 to 225 liter per minute. So, this much is the flow rate Now, plunger pumps high pressure applications as I said earlier then rotary pumps when slightly low pressure once maximum pressure goes between 1 to 3 MegaPascal, and the flow rate is 19 to 114 liter per minute. Well, these are the informations which we are from the literature available and from the experience that we have observed in testing of various types of sprayers The diaphragm once also lowest sprayers ones and these have about 3.4 Mega Pascal up to this and up to 90 to 23 liter per minute, of the these are sometimes these diaphragm ones are better for particularly for abrasive materials you can use them. Now, each has it is own requirement and each has it is own uniqueness particularly with regards to use So, we can see that what are these piston pumps? You the piston pumps are very simple once, you have seen all the pumps which we are used for our water lifting and all that there are all piston pumps or plunger pumps You can see here that this is the plunger here and inside this pump this is the one which when it goes here, you can see that suction will take place from this location here, and that the liquid will be discharged from here So, these are the walls which are closed once you pull it the suction is created, vacuum is created then the liquid will be sucked in and after the moment it is pressed when the valves will open. And the vent is created the valves will open and the liquid will go through this here Now, the diaphragm type, the types of membrane is there so, this is the membrane which is there, and then the inlet and outlet very simple you can see the inlet covers from here and because of the movement of this you will see here. The movement of this diaphragm is to and fro so, as it is moving out so, inside then it sucks in and moves the reverse direction and it is pushes out So, during that pressure see this in check valves. This check valves are direction, check valves are only talking of unidirection because, here check valve is inlet one when it is only putting inside there, the other one which is only for outside. So, these two check valves are they are very simple type of diaphragm and as I said these are good for abrasive materials. Then rotary pumps are also low pressure pumps but then they are also positive displacement Now, what is this positive displacement? Remember that it is not affected because of the pressure as such the discharge, ok. But there are other pumps which are affected because of the pressure which we call the non-positive displacement pumps So, the rotary pumps you can see here that these rotary pumps where there is a rollers are there, then the rotor is there, and PTO driven, here is the inlet. Now, the moment you have been see this rollers they move to and fro so, when they move to and fro while moving inside they suck in and while pushing that and this particular rotor keeps on rotating So, when keeps on rotating they will go to the location where the outlet is there, they will and deliver it. From the inlet point they will be sucked it so, these rollers are moving to and fro and then they do the job of suction and forcing it out this is what is in the rotary pumps is a very concept is very simple if you are open you would be able to understand what are this But, it as a designer you must know what is happening inside the pump then only you will be able to change the pump, you will be able to design a new pump and see that the losses in the pump are lesser. And then you are in a position to choose a particular pump for a particular application part So, these are the positive displacement pumps that we have talked the piston pumps, the rotary pumps, in the diaphragm pumps and the pressures and volumes which are there I have talked of these. Then let us know which the non-positive are and what are their behavior? See here, the non-positive, variable displacement pumps simple as that. The very displacement will vary as the pressure you can see here that this centrifugal pump here. So, see these