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It's hard to properly size the generators without knowing the power consumption (W or kW) of each appliance, especially, the fridges, 'air coolers' and 'neons'. I'm particularly unsure about the coolers - if these are evaporative devices they might draw 200W or so to drive a fan, but if they are air conditioners with compressors they could draw as much as 5kW each (depending on size) , with start-up surges of 2 or 3 times that. The cooling loads will be by far the greatest demand on the systems so it is worth getting more information about them. 9 & 6 kVA sound reasonable, though the clinic would probably run on less, but you don't get diesel gensets much below 5kW and petrol ones don't last anywhere near as long. If you permanently run the genset at very low load, it won't do it any good but you need extra capacity to allow for fridge compressors starting. Sorry this is so vague - I can give more accurate ideas with more details of the loads.
If the clinic is 2km away from the office, it will not be practical to run both from one generator - cable costs and power losses would be far too high - so you will need two systems.
As you say, the running time could be a worry. As well as general wear and tear, they will use a lot of fuel even if they have little load to meet. I would strongly advise you to consider a generator - inverter - battery system. This way, the generator runs when you have a large load - air conditioners, for example - and also charges a battery bank. When it cools down and you only need lights and a computer, radio, etc you can switch off the generator and run on the inverter, which converts the power stored in the batteries back to 230V ac. This system would cost quite a bit more to buy than a generator on its own, but would be much cheaper, and more reliable, to operate.
In addition, you could also add some photovoltaic (solar) panels that will charge the batteries even if the generator is not running. If you can manage without air conditioning, these could meet most of your loads. If you are buying the equipment, you should get the highest efficiency fridges you can find, and look into evaporative coolers rather than air conditioners. If you are not putting a fridge in the clinic and you only need lights and a laptop, a small solar system will be a far better option than a generator. Even with a fridge, a solar only system is very feasible.
The company I work for (Dulas Ltd, www.dulas.org.uk) has been supplying solar-powered medical refrigeration systems to Africa for about 20 years and is the leading supplier to UNICEF for their vaccine cold chain. I have helped install solar only systems for clinics with fridges up to complete district hospitals in Eritrea and these continue to operate fine with no difficulties in sourcing fuel. Although I no longer work in that department, I'm sure my colleagues there could put an outline of a suitable system together for you if you can provide a bit more information on what you need the fridges for and the size of the other loads.