Urchinhunter, you need to specify power drive, can we presume electric, 3 phase? Single phase, 220 are seen once in awhile but one needs a 40 amp breaker. I don't know what's available in NS, but assume 50 cycle which may not be a problem.
Anyway, the task is not difficult on the used equipment market. The 7.5 hp is exactly the kind of unit which small USA fire depts are unloading every week on EBay and so forth. Look for something which has support in the parts chain which is less easy to do. Look for low hours, less than 1000, clean appearance and reputable seller. Fire depts are careful about maintenance but inquire anyway. Ingersoll Rand and American Bristol might be a PITA. Try late model Mako, Bauer, Compair, Hamworthy (maybe), or even Alkin, Coltri, etc in the new, retail market. Compare the power availability to the power specified. Don't get in the situation where you have to visit Scubaboard looking for manuals, parts, advice, handholding and general consultation because there is nobody else to talk to. We will help but there are limitations.
Pumping NITROX always involves a slight risk. Properly managed, it is a relatively safe operation. Asking for a "NITROX compressor" is unsettling to me. Do you know what you are talking about and how to do it? Get some training or read some books like Oxygen Hackers Companion.