When (or if) you get the time, I suspect you need to carry out an accurate survey of all the equipment in your hospital, Delfin.
For each item of equipment, you need to ask:- "how am I going to support that item" (and how long is it going to take)? In each case you need to assess its condition, and also jot down an estimate of how long (and yes, how *often) it will take to carry out PM.
Based upon your assessment of the condition of each item, you should be able to make a reasonable guess about how long you are likely to spend on repairs (initially, at least). You may even find stuff that is broken and (or) unused that may not be worth
repairing. But (obviously) the aim is to have everything well maintained and under control.
As you go around making your inventory (or "Asset Register") of maintainable items, you should also make a list of anything you shall need to support each item (manuals, test equipment, parts etc.
Only when you have good (accurate, reliable) data available can you really sit down and make calculations that will (hopefully) be taken seriously by senior management.
Although your "equipment count" looks a little low to me, at this stage I would still suggest four technicians!
I suspect that our good friends Dave and Paul are looking at things from a "maintenance contractors" point of view, rather than that of an in-house biomedical engineering department. That is, they are forgetting the thousand-and-one other "little jobs" that in-house biomeds get roped in - or "volunteered" - to carry out. "Supporting" the clinical staff ("hand-holding") comes immediately to mind (and how long does that
take!). I have been in places where the real
work only started once the departments (wards etc.
) had fallen quiet, and everyone else had gone home!
And (as Neil has reminded us) you have to consider "real world" factors such as sickness, courses, staggered hours (to provide "shift" cover), on-call ... and (even) - days off!
* At first, I would start out with 180 days (every six-months) as a default PM frequency. With 90 days for critical (high risk) stuff like defibs, anaesthesia machines and ventilators. See how you get on with that, and then adjust (extend) the periods later if you can (that is, once all equipment has been brought under control).