I recently tested a large new lab kitchen's installation of 12 type 1 range hoods at local university's culinary arts building.
When the extinguishing system under 1 of the range hood's was activated, it took up to 3 1/2 minutes for a gas, 6 burner range burner units all to extinguish themselves.
The fuel shutoff solenoid did indeed activate because the fuel supply did eventually deplete itself.
Chapter 50 of NFPA1 nor NFPA 96 does not state the allowable extinguishment time required after the fuel supply is automatically shut off and actual cooking appliance flame extinguishment.
This time seems very excessive to me, absurdly excessive.
The Mechanical Contractor has stated that there is just 1 fuel shutoff solenoid in the entire fuel supply system.
He also stated that because of the large gas-fired appliances that the fuel piping is sized at 3 inches, and that the appliance is being fueled by residual gas in the piping.
Can anyone offer insight/comments and suggest a code which does reference this situation?