Hint: speak to the companies likely to bid ... they will have all the data (and more) your little heart desires.
Asking a company who is trying to sell you things how many you should buy.......I am sure they will give you honest advice not biased in any way.

How many do you have at the moment?
Is that enough, too few or too many?
Surely you know best how many is needed rather than taking an average of some research project. Every hospital is different in the types of patients treated and the protocols used so what is right for one is not right for another.
At one place I worked (which was a specialist centre) we had more syringe pumps than IV pumps. At this hospital which is three times the size we have slightly more syringe pumps and three times as many IV pumps. And they are all in use.
Tell your purchasing department to............
Robert