Kitchen Wet Chemical System After Unpermitted Appliance Changes
A restaurant has a 12 ft Type I hood over a gas range, two gas fryers, and a gas charbroiler, protected by a wet chemical system. Since the last semi-annual service, the owner replaced the 4-burner range with a 6-burner range and added a small gas griddle at the end of the hood. No nozzle changes were made; the original layout has one nozzle per appliance. You also find the manual pull station mounted on the wall inside the cooking area, 4 ft from the hood, and a fusible link on the griddle that has been painted over. The gas shutoff solenoid is wired to the system, but the electric fryer circuit is not. There is no Class K extinguisher within 30 ft. The owner wants to know whether adding a larger wet chemical tank will cover the new appliances.
1. Will a larger wet chemical tank solve the problem created by the new range and griddle?
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No. A wet chemical system is designed appliance by appliance from the manufacturer's listed installation manual: each appliance type has a required nozzle, flow rate, spacing, and placement, and the tank size follows from the total flow at the listed pressure, not the other way around. Replacing a 4-burner range with a 6-burner range changes the appliance footprint and the required coverage, and adding a griddle adds a new appliance that has no listed nozzle at all. A larger tank with the same nozzle layout would deliver more agent through an inadequate distribution system, leaving the new surfaces unprotected. The correct path is to have the manufacturer's distributor redesign the system for the new appliance line-up, submit the design to the AHJ, install the added nozzles and piping, and retest. Until that is complete, the new appliances should be taken out of service or the system tagged out, because the owner currently believes he is protected when he is not.
2. Evaluate the manual pull station and the painted fusible link. What is the required correction?
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The manual pull station is in the wrong place. It must be located along the path of egress from the cooking area so a person can actuate the system on the way out, and it must be reachable without entering the hazard zone. Mounted inside the cooking area 4 ft from the hood, it may be unreachable once a fire starts on the cooking line. Relocate it outside the cooking area but on the exit path, at an accessible height, and clearly identified. The painted fusible link must be replaced, not cleaned. Paint insulates the link and changes its thermal response, so it may not operate at its listed temperature; the replacement must be the correct rating for that specific appliance and installed per the listing. Links should be inspected at every semi-annual service and replaced whenever painted, contaminated, or of unknown rating.
3. What else must be corrected regarding fuel shutdown, extinguisher coverage, and system maintenance?
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The fuel shutdown is incomplete. The system must shut off every fuel and power source to the protected appliances, so the electric fryer circuit must be added to the shunt trip along with the gas solenoid, and the shutdown must be proven by test rather than assumed. Coordinate the exhaust and make-up air with the system per the manufacturer's listed sequence and the AHJ's requirements, and verify the sequence actually occurs on actuation. Provide a Class K extinguisher listed for cooking media within the required travel distance of the cooking area. Confirm the system receives semi-annual maintenance and that the current tag reflects the new appliances, and require the distributor's redesign to be reviewed before the next service. Document every deficiency in writing to the owner, with a copy to the AHJ if the appliances remain in service.