Are sprinkler systems allowed to have additional valves downstream of the system riser (e.g. for small tenancies)?
Outside the USA, it is common for the sprinkler systems in shopping malls to have individual valves serving each tenancy, so that if a tenant wants to fit out a store, they don't need to drain the entire floor, just the pipe leading to each tenancy. Does this arrangement comply with NFPA 13, if so, is each valve treated as a system valve, does it require a check valve, pressure gage, drain valve?
In my experience, in the US, you tend to use spades to isolate an individual tenancy.