My compressor is an old 40-50 year old Champion R15B on a 60 gallon tank with an automatic drain that didn't work. The comparable replacement was expensive and had the same issues as the old one in that it had a pickup that comes in through the side of the vertical tank and hopefully drains the condensate from the bottom of the tank. The new drain is attached at the pipe fitting at the bottom of the tank and drains all of the condensate and If required I can adjust how often and the duration of the drain.In "South Central" Pennsylvania in can get pretty damp (not like the Gulf Coast, but my air conditioning puts out plenty of condensate five months of the year). I seldom use my compressors, but when I do they run a considerable time in minimally conditioned spaces (including the garage or outside). Only one of the compressors has a full-time filter/separator, and neither has an intercooler or dryer. I always open the drain valve and blow out condensate before I trundle them back to their storage location. Both compressors are 20+ years old and I haven't had any problems.
Amazon lists a number of options for "air compressor auto drain," ranging from $30 – $145 in the U.S. Amazon UK has the electrical ones for £20 – £35, and a float version for £8.29 (Float Drain Valve air compressor automatic drain valve condensate drainer Automatic Drain Float Drain no noise Automatic drainage Air compressor drainage : Amazon.co.uk: DIY & Tools). You can get this one in the U.S. (including the 1/2BSP connections) for $29.
I chose the AliExpress one as if I'd have got it through Amazon or Ebay there would have been freight and taxes added coming into Canada, Bezos doesn't need more money, I could afford to wait a month for the drain, saved some money in the process and still got a good , reliable product.