How many concealed hinges per door

Hi all
Recently built a large, larder style unit with a mate to house a newly installed boiler at his house

Just made the doors, 18mm MDF which are now going to be sprayed gloss white
The doors are fairly heavy and a size - 2 doors in total, approx. 1100x675mm and weigh 8.8kg each

Have brought Hafel concealed hinges, was planning on three per door but am now wondering if we should fit four per door due to size and weight

What do the pros reckon, many thanks

 

Thanks chips for the link but do I have to now work it out for myself ?????

Saturday early evening and feeling well lazy tbh

Can you advise further, or maybe pop over and fit the hinges for me, thanks, I'm in Essex by the way

 

Thanks Chips and Jit, very useful info

So three hinges per door it is then, all will be fine. Looks like I will be fitting them myself then, my mates a great bloke but totaly useless at diy !