I was asked to validate a sprinkler system design from another designer, therefore the question I am about to make is a consequence of this situation.
When presented with different hazards distributed throughout a building we protect each room with the Proper K- Factor sprinkler and distribution.
A control valve is installed between the system riser and the sprinkler distribution, the K- factor of the test and drain valve within the control valve is the same the sprinkler system has. This Leeds to having to install a control valve for relatively small rooms just to accommodate this situation.
The question is if this is just a good practice or if it is mandatory to do so.
Having researched the NFPA 13 code and handbook I understand that the only requirement for a control valve is not to exceed the maximum area protected. Therefore It would not be necessary to install a control valve for every K- factor distribution.