good night in advance I appreciate your attention I hope someone can help me the matter is that I have a duplex hydropneumatic equipment consisting of two water pumps at 220 volts a hydropneumatic tank and a control board which is composed of two pressure switches two contactors an alternator Simultaneador and two stop-off buttons - automatic. the thing is that both pressure switches activate at the same time and turn off at the same time, handling a range of 20 - 40 I understand that this is supposed to be done alternately according to the water consumption and if the consumption is greater and continuous water the two pumps should come together but I do not want to know if someone can help me how to calibrate said pressure switches thanks.