If two combination standpipes were interconnected, but there was one floor control valve, that would still mean the floor was supplied by two or more combination risers. Correct?

I'm a little confused at a code that states a high rise shall be served from two or more combination standpipes/sprinkler risers.

I am 99.9% sure that means one control valve is acceptable providing that before that valve is double fed. If one standpipe goes down, that control valve still gets it's water.

If you have a high rise building, as defined by the IBC or NFPA 14, you are required to provide two vertical fire protection water supply pipes. We call them standpipes. You are also required to provide separate, interconnected FDCs, in my mind and in accordance with NFPA 14. Interconnect the vertical water supply pipes at the base of the riser or at the top of the riser, and it complies with NFPA 14. Interconnect the sprinkler control valves, and its perfect reasonable and it is legal under the IBC/IFC and NFPA 14. They are just a isolation point in the system so the rest of the automatic sprinkler system is not compromised.

Here is my real life example: Fire on the 10th floor of a 30 story high rise. FD responds, the sprinklers suppress the fire, and the firefighters close the valve. One hour later, another fire occurs on the 22nd floow. FD responds, along with a bunch of police officers, and finds a working fire controlled by the sprinklers on the 22nd floor. The fire goes out and the cops arrest an arsonist on the 1st floor when the FF recall service traps the stupid bastard. I witnessed this once 25 years ago. My point: the codes work.

It's not that hard of a problem. I think we are getting lost in the terminology.

A.7.1.b shows a system with high and low zones. Each of the zones has 3 separate standpipes feeding multiple floors. It does not show sprinkler control assemblies. The standpipes are interconnected as is 7.1(a) which shows a low zone only high rise and one of teh standpipes being a combination riser. If you take the high zone shown in 7.1.b as being 10 floors, and you have designated the one on the left as being the 'combination riser', those 10 sprinkler systems are being fed from that combination riser. The high zone in 7.1.(b) now looks much like 7.1(a). If you have to replace a FHV or shut it down to do any service on that combination riser, you would be shutting off the sprinkler systems fed off that riser also. The sprinkler systems are therefore not truly 'dual fed'. Unless you link the sprinkler systems and go with one of the designs previuosly discussed on this post.

6.3.8.3 to me would not require sprinkler systems to be dual fed but says when they are being done, signage for isolation valves are required. This would further insinuate that additional valves for isolation would be required.

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