In the states there are usually a couple of routes to go.
Most manufacturers, Trane, Carrier, York have a rental division specifically for providing exactly what you are asking for. It isn't insurance per say but they do offer rental chillers, air handlers, pumps, tower, etc. In the states most of them are set up with regional warehouses such that they can have a rental unit up and running within 12 to 24 hours, sometimes even quicker. What is essential is that your building be set-up to seemlessly integrate the rental unit into the existing system. Available electrical connections and tie in points to the system are worth there weight in gold especially in a production environment. It doesn't do any good to be able to have a chiller on site in 6 hours and then have to wait another 24 hours paying people overtime installing temporary connections. It's much cheaper to get these things ready on the front end.
The other route is to work with one of the larger HVAC service companies (could also include the service arm of one of the manufacturers). They could provide more of the "insurance" by entering into a service agreement where they come and do annual, bi-annual, monthly, whatever is necessary service and inspections for a fixed cost. You can usually add to the agreement certain conditions for responding to unit failure and even include response times for installing rental equipment.
I am sure that actual monetary insurance is available to cover lost production should a chiller go down. But, from what I have seen redunancy and a close working relationship with a top notch service company will be what saves the day.