I suspect that the Nardi operates on the same principle as my Coltri MCH-6, having both a coalescing filter to address liquid water and a molecular sieve to address water vapor. The coalescing filter would be the short tower and the molecular sieve would be the taller tower with the outlet hose attached.
On the op's set-up the taller cylinder is the separator. That short stubby tower looks like a home-made last stage air-filter. That red knob on the taller one is the moisture bleed. I don't know anybody that makes a short filter that would fit that short tower. Look at the pic i posted and see how tall a final stage filter usually is. Its possible that this set-up was originally for air-tools. No way that short filter would supply air dry enough for airgun much less breathing air.
The discharge/fill hose is on the last stage (the taller one)
No its not. Its coming off the short cylinder. The pic i posted of a "standard" Nardi has the hose coming off the final , squarish filter. The op's set-up has the hose coming off the short,stubby cylinder.
