If you want to work in a room with a certain temperature, what you have to think about is that there is a lower evaporation rate of the refrigerant ... right ?, because if not that way we could not cool to lower the temperature of that room . However, the lower amount will depend on what has been projected from DT, (difference of tª between the chamber tª minus the average evaporation of the refrigerant gas) that commands the relative RH of the air that the enclosure itself must have. Once that DT is found, (it is normal that it is 10 ° C, but it will depend on the product to be cooled), we therefore have the evaporation temperature. Once we have the evaporation temperature, we can know with the characteristic of the refrigerant, in this case R-404A, THE PRECISION of work that we will have at low pressure. Let us give an example, if the CAMERA Tª is -20 ºC means that it is normal to have an evaporation tª of -30 ºC, for that tª the low pressure should be close to 1.05 relative bars, that is, measured with the pressure gauge For the working pressure of the discharge is another consequence of the system that is used for condensation, ... the normal is air and we should have some system that maintains that tª even if it is with pressure switches that handle the condenser fans quite normal should be + 45 ° C, then the pressure corresponding to that Tª would be 19.2 bars. With this data the VET is calculated to move from one pressure to another. 20190427_021718.png [65.63kb] 20190427_021812.png [23.89kb]