When pressurizing with nitrogen the system affects the compressor - and if not, how did it perform this pressurization?
Obviously, to carry out the pressurization, it is necessary Obviously a nitrogen tank, and to adapt a service valve that you can connect to your pressure gauges, with which you check the gas.
If the Nitrogen tank has its pressure gauges, it would be better, because that way you protect your gauges more so that they are not damaged due to the pressure of the tank, since they can be up to 2000 psi. I recommend that you investigate more about the subject, as it can be dangerous to handle these pressures without precaution.