 So, welcome back, after having seen the LV saturation line, after seeing the table 1 and table 2 from the steam tables, now let us try to understand, how do we classify a particular system in different zones, taking the help of LV line. So, once we know P-SAT and P-SAT from the LV line, how do they help us to identify a particular system that it lies in this zone or that zone and that is very important to understand. Let us try to understand zones on the PT diagram using table 1 first and we will repeat the same exercise using table 2 because both table at table 1 and table 2 actually help us to identify a particular thermodynamic system to identify the zone in which it lies, alright. So, let us come to the PT diagram as you can see from here pressure temperature diagram and a LV line which goes from TP to CP, you have got a L region and V region over here. On the right side of this LV line, what we have is a superheated vapor zone, it is shown over here. On the left side is the subcooled or compressed liquid zone as shown over here. So we know this critical point coordinates and when the pressure and temperatures are beyond the critical range that means pressure is beyond the critical pressure and temperature is beyond the critical temperature, we lie in a supercritical fluid zone as shown over here. And also we know that if the system lies on this line, saturated line, we know that it is a two phase zone, it could be saturated liquid, saturated vapor or two phases in equilibrium and that is what we see when this system lies on LV line. So, these are different zones, subcooled compressed liquid zone, superheated vapor zone and supercritical fluid zone. The question is if I am given the PT coordinate of any thermodynamic system or state, how do I identify where it is at lie, which zone it belongs to and that is the question right now. So, let us start answering this question and let us take the reference of table 1 in this case and when I say table 1, we know now that temperature is the base in that case. So, for any given system now, we have got its PT coordinate, the pressure and temperature coordinates are known to us. We know that the state lies on at a particular pressure and particular temperature and this is the only given data to us. If we take temperature as a reference, because we are using table 1 right now, I will take temperature as a reference and corresponding to this temperature, I will be able to find out P sat T alright. So, first step is to find P sat T for that given temperature. Once we know this P sat T, the next operation is to compare this value of P with this P sat T and that is very simple thing and with this comparison only, one can find out in which zone the state lies. How do we do this thing now? So, I have got different possibilities which I have shown under different serial numbers and then I do the comparison and identify the zone in which this state lies. Let us say the first state, the first case is here that P is equal to P sat T. So, for a given temperature, I found out P sat T and we found that P is equal to P sat T. What does it mean? It means that for a given temperature, the corresponding value of P sat T lies over here. That is why the pressure happens to be P sat T over here. It also means that this T is T sat P, is not it? And the coordinates of this state will be P sat T and T sat P and therefore, we say now if P is equal to P sat T, the state lies on the saturation line as shown over here. So, this P T point, this state of any thermodynamic system lies on the LV line. So, it could be a saturated liquid, saturated vapor or it could be a two phase mixture in equilibrium and that is what we can predict as soon as we know the temperature, find out P sat T, compare this and come to the conclusion that it lies on saturation line as shown over here. The next case is if I find this P is less than P sat T. So, the given P is less than P sat T, this is P sat T and you can find out from here that if such a thing exists that P is less than P sat T, this state lies in a super heated vapor zone now, it is in this condition and correspondingly we can say that the serial number 2 case is a super heated vapor zone, this state lies in a super heated vapor zone. The third case will be P is more than P sat T, if the pressure, given pressure is more than P sat T, it lies in a sub cooled or compressed liquid zone. It can lie anywhere in this zone actually, is not it? And therefore, we say that it lies in a sub cooled or compressed liquid zone. So, we have identified all the three possibilities, the super heated sub cooled as well as two phase zone. The other one is we have already mentioned about that thing which is a super critical fluid zone when the P is more than P critical and T is more than T critical, the state lies in a super critical fluid zone that is in this part over here. Here in this case, the temperature has to be more than 373.946 degree centigrade and the pressure has to be more than 22.064 MPa meaning which you are lying in super critical fluid zone. So, this is the way that after referring to table one from where I get the value of P sat T for a given temperature and I compare given P with this P sat T and come to different conclusions in order to know in which zone the given state. Thank you very much.