We (EBME) have an arrangement with our supplies department that any requisitions for medical equipment are refferred to me if they don't recognise the equipment or the model as being one of the "usual" ones bought by the Trust. There is no written policy, although it is well known that the trust has a "standardisation policy" for medical equipment !
There have been a few occasions when a consultant has kicked up because he was told that he couldn't have a particular piece of kit because it wasn't the standard unit, but in general it seems well accepted and the majority of people acknowledge that it is a sensible approach.
Supplies always send a PPQ form for medical equipment which is either a new model or which hasn't been purchased for a couple of years. If I don't approve the PPQ form - it doesn't get bought - unless someone signs a disclaimer accepting personal responsibility for the equipment and relieving the Trust of liability. Not many people are prepared to sign up, surprisingly enough, so we can effectively control the standard of equipment which ends up being used on patients.
How does everyone else deal with these issues ?
