The container involved is http://www.denios.co.uk/kategorie/c100400703045_Fire-protection-container-BMC-L-720X.html with magnetic door retainer as a option.
Normally door closing system is linked to their own control panel. ( the heat detector triggers the door magnets to release the doors, closing them and sealing the container to stop the spread of flames). But it looks like the purchaser wants it linked direct into the existing fire alarm system.
The above is for interest only and I have shelved this enquiry because its outside my expertise. They seem to want a simple answer so I have suggested they employ the services of a fire alarm expert.
Tom, I know you have shelved this enquiry, but my answer, having looked at the article in the link, would have been;
In my opinion;
a) If the container was a free-standing unit outside and away from the premises containing the fire alarm system, if the insurance companyy were happy, I would say that interfacing the container fire detection system to the main building system would do no harm and only be of some benfit in knowing there was a fire situation in the container.
b) If the container was sited within the building;
i) If the building fire alarm system was a P, L1 or L2 then a detector wired directly to the building's system should be installed within the container and the existing heat detector ignored.
ii) If the building fire aalrm system was any other category, a detector(s) wired properly into the buildings fire alarm system should be sited outside the container doors. The container's heat detector could also be interfaced into the building system as an option.
* The term interfacing in the above means by use of relays thereby electrically isolating the two systems from each other