 yesterday we had start system we had uhh as far as the main system components are concerned, there can be a variation in terms of the laterals how the laterals are laid that will see subsequently but in general the other components which are usually present in a drip irrigation system they have been already discussed at this juncture we will like to look into the again some thumb rules which have uhh been brought out with respect to the experience and this can be quite a useful uhh thumb rule in terms of the general estimates, equipment requirement in the form of with respect to the type of crop with respect to the row spacing, other items which are uhh these details are expressed in terms of our plants per hectare or of emitters the lateral length is meters, this is again these are the average values which have been found from uhh various areas of the world, it has been seen that if you adopt these values your designs will be quite within the range within the required uhh limitations or the constraints which you which you would like to put the design through. The types of uhh crops are divided into different categories, broad categories again and the only categories which have been picked up in this particular uhh uhh table are those which are suitable for this type of irrigation, so you have ordinary orchards where the row spacing is this is in meters is around 6 meters, the plants per hectare in these type of orchards are around 250 and the emitters per hectare which are required they generally vary within this range between 500 to 1500 and the lateral length the overall lateral length in meters per hectare is around this value 1900 meters per hectare area. Then you have uhh dwarf orchards which also includes the vineyards where you produce the wine grapes in this case the spacing is of the order of mining should of around 3.7 meters and the other values which are again you can say the average values these are the emitters per hectare and the length of lateral which is required in meters per hectare. Then you have another category varies white spaced row crops, these drip irrigation systems are also being used these days for the row crops and 2 types of row crops have been recognized one is the wide spaced row crops and close spaced row crops, in the case of white spaced row crops where the row spacing is around 1.5 meters you have these values the order of magnitude of the plants per hectare, the emitters per hectare and the lateral length in meters per hectare is this order of magnitude. Then you have the category where you again use the drip irrigation system is the green house close spaced row crops, in which case the spacing is still smaller in comparison to the previous case and you have these order of magnitude. Now this will give you a general feeling that we will talk in terms of the density of this network of literals which you are going to have it will vary considerably with respect to what is the type of crop in general which you are catering to. In case you have those crops which are of the type of orchards which are individual tree plants or individual plants the size can vary that is why you have 2 categories in one case you have the full grown trees, in other case you have the dwarf orchards where you have the plant sizes are smaller and the requirements are also going to be less in comparison because of the root system the type of root system they have. And these are the general the order of magnitude only because this is not incorporating anywhere the effects of climate and you have seen so far you have seen that the climate has a very significant role to play in terms of the evapotranspiration activity. So the evapotranspiration activity how much is the actual evapotranspiration is going to be decided by the climate only. So you cannot talk in terms of the specifics because the specifics will vary from one place to another place depending on what is the variation in the climate but since in most of these cases when you talk of specific type of orchard you will find that since it has its suitability to a particular climate you will have the climate variation very nominal because if you talk of wine it has a suitability for a particular type of climate but still is not true that it cannot grow I mean if there is even a little variation in the climate it can still grow the variety will be different there will be some other influences of the local climate but you can have different types of crops of the same crop under different climates and from that angle you cannot assume these things to be the specific values they are only ranges which have been given as a guideline to the designer so that he can get a feeling that how much when you start with the first initial estimate you can start with some value which is reasonable and start refining those designs to arrive at a final design parameter or set of parameters okay. Now let us go on to the next very important element of this these systems which is called emitters a different name given to this sometime you call them drippers or emitters so what is the rule of the emitter is a device to apply water to the soil from the distribution system emitter is the device which ultimately supplies the water from the distribution system on to the ground surface at any point whichever is the point of your interest but we will not talk in terms of the point right now because we are going to discuss the various types of these emitters which are available and is not only a point source it can be a line source also. Let us let us classify them accordingly if I say the types of the emitters you have two general types of emitters one are point source emitters and the others category is the line source. We will come to their what do we mean by the point source and what do we mean by the line source emitters in a short while but before that is equally important to know what are the attributes of emitters which are generally desirable by a designer you like to have these attributes in an emitter these attributes are they should be the specific type of emitter should be available small increments of discharge that you should have the category of the or the type of emitter should be such that you should be in a position to have different emitters with a very small incremental value of discharge let us say an increment of 1 litters per hour. So you should have emitters of the same type which is which is able to give you a specific discharge rate but the next one should be having a variation of as small as 1 litre per hour otherwise you would not be able to have a flexibility in the design because in these cases the amount of water which you are dealing with or which you are talking in terms of they are very small so if you have small increments you will be having a very good flexibility in terms of selection of these emitters and having designs which can be done which can be which can take care of the requirements all those various constraints quite effectively. The other attribute is the flow should be within narrow limits as a function of operating pressure which literally means that if you change the operating pressures the change in the flow should be again a very nominal this is another attribute which is important from another aspect a large flow area in general you should have emitter which has a large flow area because of the fact that if you have very small flow areas you will have the clogging problems. So to avoid the problems of clogging if you have large flow areas it will be much desirable then the emitter should also resist degradation and the degradation can be due to temperature fluctuation, solar radiation that means you should choose the material of the emitter in such a manner that the degradation is minimum over time because of the temperature fluctuation which you will normally have in every place and because the solar radiation there are some emitters which might become brittle their design characteristics might change their behaviour might change after a very small duration of operation. You should also ensure that the useful life of emitter should be known this is again since all these emitters they have a definite life if the designer is knowing that how much is the life of the emitter when he makes the computation when he goes in for the total cost analysis of the system he can design the system more effectively if he knows that what is the useful life span of the emitter because this is the most important device in the total system because unless the water comes out of the emitter whatsoever you have in the background before the emitter is of no use because ultimately this is you have taken all the trouble provided all the other components of the system just to ensure that the proper amount of water flows through the emitters and is dumped onto the desired place at the proper time and with respect to the proper rate. So if it is not doing that function then this is the wastage of the money and your system cannot run successfully you will have to you will have to abandon the whole operation maybe. We will go on to the description or brief description of these emitters what are the various types of emitters which are available because I will be only discussing with you some of the common types which are in the market and which are more popular with the users they are many because this is growing into a very successful and very big industry and you will find that there is a new model coming there is lot of research going into this area and since most of the emitters they have some problem with the other and even from the cost point of view to make it more cost effective people are trying various materials people are trying various shapes people are trying various sizes of these emitters so that they can have more flexibility they can give the designer and the user more flexibility in terms of the usage of these drippers under varied conditions if you can use the same dripper in a very large range of conditions you will be saving lot of expense which is otherwise will become essential if you have to have different emitters for different types of crops and for different seasons so from those angles you will find that there are many types of emitters which are available in the market and let us discuss some of those which have become quite common. Now we have two categories as we have just mentioned one is the point source emitters these point source emitters as the name suggests they are applying the water at a particular location at a particular point of the field so each emitter is trying to cater to one individual point of the area that is why they are called point emitters whereas the line emitter on the other hand is catering to a elongated length of the area so along that line but in both the cases you will find that as far as the outlets are concerned from where the water is coming they are individual points only in the case of line source you are having those points more closely placed so ultimately when you look at the area of influence of each individual point in the case of point source they might not having any overlap whereas in the case of line source they will have the overlap that is why they are two different names given to this. Let us look at the point source emitters there are various categories one is long path long path spiral route in this case you have a system where you have this type of arrangement this is the inlet the water enters from here I will say entry this is something this is a knob which goes on to the lateral it just pierces the lateral and this is the inlet point then on this side you have situation where you have a groove this is happening is that this is these are small little spiral grooves and all this this is the spiral area so what you are doing is that you are making the water go around these spirals so that they can they can be some dissemination of energy which is available because in most of the cases the pressure which is prevalent in the literals is much much higher than the pressure what you want the water to come out with. So in all these emitters there will be one general thing that there will be some way by which some mechanism which has been adopted by which you can have lot of energy dissipation and that energy dissipation in some case is ensured by having more area with the water has to travel in this case is that only basically the long path spiral groove that is what the name suggests so you are having the water enters the inlet and after that inlet you have a spiral path which is very long path is to ensure that the energy is dissipated and then you have the water coming out of this place this is the outlet or the exit point similarly the same thing can also be done by having a long small long tube so accordingly you have another system where you might be having a very fine very fine tube and the end of this tube you have an area which is enlarged area again for dissipation or dissipation of energy and this case this is called capillary capillary or spaghetti and this tubing can also serve as an emitter you have another a different shape this is basically a in this case you have this is the load most part in this case all the components have been shown separately they have been detached they are small disc sort of things which are inserted in each other this is the load most disc which is in the form of a cup and then you have this is this is called brace then you have a spiral which regulates the flow so that spiral is something of this nature this is the spindle here and then the water which is entering is moving through the spiral this is the spiral and on top of that you have a membrane and this membrane is a flat membrane this membrane is used for pressure regulation now if you will put more pressure on this membrane then it will let less amount of water pass through the spiral because of this since this is a flexible membrane you will find that if you will have this loosely held there can be more flow which can pass through the spiral if you have the membrane which is which is slightly tightened you can reduce the flow so this is another and then you on top of that you have a cap you can have a cap which is used to which can which is put on the top so that no dust enters the the total system and this this becomes a compact system when you put them together join them or rather they can be a screw which can be tightened then you will find that this can be adjusted manually to regulate the flows as per your requirement or there might be some calibration which is given in the in terms of some indicators that how much you have to tighten to get a proper amount of flow these are the various uhh some types of the point source emitters now let us look at the line source emitters in the case of line source emitter there is only one type of emitter which is very popular and that is basically a combination of two pipes this is the lower pipe and if I take this section of this this is the pipe and this pipe has openings this will have a opening here somewhere this level then on top of this there is another pipe which is not a complete pipe which is only a segment of pipe which is this may be half the only half is not a complete circular pipe only a segment of the pipe which is put on top of this pipe and this is put on top here this becomes a complete single unit the water moves from this inner pipe the water run in the inner pipe this is the lateral and then the water goes out of these these openings the number of these openings is much larger than the number of openings from where the water is coming from the the inside pipe. So again there is some level of the energy dissipation because from this the water is moving into another pipe and the area is very large the velocity will be much lower and secondly is also having the distribution with respect to the spacing of these openings so this is the exit point for water similarly there will be more that is what is called the line source because now in this case this length of the perforated tube this is basically having is the tube which is having an inlet inside here and then the perforation on the top portion of the tube this perforated tube can cater to the requirements of a row crop much easily than the other type of the point source can can take care of. So this is another emitter this also will come under the category of emitters but a line source emitter is also possible that these emitters which we have discussed they can be they can be placed in different manners in some case the point emitter of a particular type it might be that means the emitter is is not attached on the on the line of the later it is not an online emitter is inline emitter that means the the emitter is embedded inside the two ends of the later. So let us see what are the various arrangements which might be available in different types of these emitters let us take a case where you have a single exit long path which is installed in that in this case what you will have you will have a the mechanism or the the basic philosophy of emitter will be that long path spiral strategy through which it will be and disseminate the energy which is available we will just make a line sketch of this if this is the emitter this is the emitter which is this is having when you say inline similarly this is the one this side and when you say inline that means you have your later this is embedded within the section of the later so this is the the later the water is flowing from this end to this end and this is one section of the later this section is joined through this emitter this arrangement is called the inline emitter arrangement and in this particular case what is happening is that somewhere here if this is the centre line of this pipe somewhere here you have the entry point through which the water is flowing and entering the spiral here this section will be having the spiral and water water moves from this and it goes through the spiral somewhere here is the water exit so it will it will move through the spiral around this as we have seen in the previous case and by the time it comes out it will be at a much lower pressure and the charges can be regulated with respect to the the general flow the pressures prevailing in the laterals that is the case of inline the same thing if you want to use as other situations where you have another type of emitter the same the long path emitter which is laid inline but you have more number of open in the outlets and those outlets might be through the form of some tubing which have been provided at some level here I think I would not go into the design or the variations of different types of emitters because our time is not we do not have that much time to discuss all these details my intention is just to give you the various variations which are possible in terms of the philosophy how we can how many types of emitters we have and how they are used whether they are used inline or whether they are used online. Let us look at an online emitter now which is of the type single exit RFS type emitter which is installed online in this case you have a let us say that this is your little and you have this is what is the lower end of the emitter which has been placed into the later this is the section of the body of the emitter the water enters water enters here this is the RFS in this particular case you can see that the dissemination of energy is through by having an RFS and then having a very enlarged area and then the water moves out of this opening here so then after going through this enlarged area water this is the exit portion of the water. Another case you might have another arrangement where instead of having this enlarged area might have an RFS and then that RFS has a spiral area so in that case it will be the it might have a vertex chamber in which there will be some dissemination of energy and then the water moves out of that so the basic philosophy remains the same you have to provide some way by which you can disseminate the energy the excess energy and also have the sensitivity of this arrangement so that by changing the pressure you must have some desirable change in the discharge that is that there is a basic philosophy then the other things which are important are you have already discussed that you you should not have a situation where it gets clogged very fast. So from those angles you will see that these things they are more in number they are more in designs because the fact that people are thinking in terms of achieving these objectives by having different types of designs and people keep on experimenting that is why there are so many of them in the market and you can select one which is which is cheap enough as well as it delivers the goods. There is one node which is which I will just which is known by the pressure compensating emitter and this case what they have used is this is only the part of the emitter only we have not shown the lower part or it is put on to the lateral so this is only the part of the emitter which is indicated here and this case what you have is that you have on this emitter you have a situation where you have a sort of this is the flexible ring and along with that you have a diaphragm and this diaphragm is having a port opening here. Now this diaphragm depending on what is the pressure here because the water is going from this end and then you also have a you also have a notch here and when the when the pressure is less this membrane will be in this position in the present position this is the relaxed position of the membrane this present position is the relaxed position of the membrane and the pressure increases this membrane will have a tendency to go up and it might take a position which is somewhat here and because of that position it will have a tendency to reduce the discharge. The opening will reduce the this is the portion from where there is a portion here which is connected with this area and this port is also the port will also have a tendency to get close because of this this notch the closer it will be with this wall it will have less and less amount of water going into the this zone. So because of that when the pressures are very high it will it will try to have a the position of the membrane will be readjusted to control the discharge and this these are the openings for the water exit. So here again the mechanism which is adopted is to ensure that by having the fluctuations in the pressure you can you can have a mechanism by which you can have a control in the discharge should not very much even if the pressure has has changed to a large extent. So within a range you can you can ensure that the discharge which is the requirement the amount of water which you want to come out it should not it should not change much and that is done by the staff which is provided here. Now with that given you a reasonably good idea about what are the various types of emitters which you will you might encounter when you when you select from the range which is available but ultimately the the usage when you use the point source or the line source if they can be used for all the types of crops which you have. For example if you have a if you have a point source now in the case of individual trees if you have a point source if this is the tree in plan in the case of a point source you might have the later and if you have the point source depending on the requirement of the tree you might have a number of those emitters put here may be 4 of them may be 8 of them depending on what is the requirement of that particular plant and also the number can change with respect to their age in the beginning they might require less water you can you can have less number of these emitters. At the same time you might have another arrangement where you have instead of 1 laters passing this tree they can be 2 laters in that case you can have 2 emitters on each lateral. There can be another situation where you want to use a line source for the same you have this tree you want to use the line source so in that case you might have either 1 later and on that later you might have a segment of perforated emitter and that emitter will have these perforations so this is the line source which is again getting to the requirement of the tree. If one is not sufficient you can have another one the 2 laters going and 2 of these sections of perforated pipes taking care of the requirement. So there is no hardened fast rule similarly if you are talking of the other extreme which is the row crop so if you take the row crop now in one case I can have a row crop this is the one row of the crop there is another row of the crop so if I want to let us say that you have a singular situation now in one case for this row crop if I want to use the point source I can have this only it is going through the row crop and having these individual emitters getting to the requirement of the total row only thing is that the spacing of the emitters will have to be adjusted in such a manner that you are taking care of the requirements of both the rows and in some cases if the rows are close enough the requirements of the crops are not very high you can even use a single row of a single lateral concaited to 4 rows and 2 rows on this side 2 rows on this side of the crop at all is a function of what is the demand what is the requirement of the crop what is the type of the soil so many all those things you are quite aware of now that how we all those things influence similarly if you have a row you can also use the line source for getting to the requirements of the row crop so these things can be used interchangeably and there is lot of flexibility which is available to the designer he has to he has to go beyond this layout and beyond these details only he has to go to the level of even going for the cost benefit analysis how much is the cost which is which he has to incur so when you talk of these designs you have to go to that level you have to go to the level of the efficiencies those will of course we will go through all those things the details which are the technical details and then ultimately you have to also look at the financial aspects of these designs okay. Any question at this stage okay then we will stop here.