I think the only safe way to undertake training is if you are aproved by the company who makes the equipment. This means you should have the same product training as their reps / clinical trainers (depending on who they use to do their training) - which would be quite a task if you have lots of different pieces of equipment in the library !
We've had a few "key people" trained as trainers by companies such as Graseby and Alaris and they now act as advisors for people who need help setting equipment up. Despite that, we still organise regular training sessions for any clinical staff who wish to attend (or are nominated by senior staff) which are run by the company clinical trainers, so the training isn't just cascaded down - it's done first hand.
There is no point doing staff training if you don't have a proper competency based system with proper evaluation in place. The trainer and the staff being trained have to sign-off their competency and the document kept on file. If you haven't got a written record of the training being done and the competency being assessed, then you might as well not bother because it's meaningless if there is an incident.
