Annual Hood Suppression System Inspection


Recently, we had the opportunity to observe a semi-annual inspection of a commercial cooking fire suppression system. Before we get too far into this we would like to point out that we talked with one of the company’s owners as well as the technician about our presence there and the questions we would ask the technician. Neither of them had a problem with this request.

To give you an idea of the size of the commercial cooking operation involved, let me set the scene; essentially, it is a small commercial cooking operation that is used seasonally. Hamburgers, chicken tenders, onion rings, and fries are cooked on the equipment. All cooking equipment is powered by electricity. However, the size of the “operation” does not matter. The approach to inspecting commercial cooking suppression systems, in compliance with NFPA 17A and NFPA 96, ought to be the same regardless of the size and frequency of use of the operation.

The technician wasted no time in getting to work. He produced a copy of the inspection from last year and reviewed it with us before starting his inspection. He checked the control box that housed the triggering mechanism for the suppression system and disarmed the mechanism. He also removed the baffles from the hood plenum and looked inside. The technician took the tension off of the cables connecting the triggering mechanism to the fusible links. He replaced the fusible links (which look very similar to the pulls tabs from soft drink cans from the 1970’s  – only thicker). He took the time to show us that the temperature rating and the last two digits of the year were stamped into the links; in this instance, 12 for 2012 and 500F.

We asked a question about how the technician handles the cleanliness of the hood as it relates to the fusible links and the technician’s inspection. The technician stated that this hood looked fairly clean but he has seen other hoods, particularly in high volume fast food operations, where the grease and residue covered the fusible links, in effect insulating them from the heat, thus making them potentially ineffective if a fire were to occur in the hood.  It is important that technicians performing cleaning inspections specifically discuss the amount of grease and crud build-up with the owner or manager. He also removed the nozzle caps and checked for debris or other gunk in the nozzles.

Next, he removed the CO2 cartridge that provides propellant to “push” the chemical agent through the system and manually operated the hand pull to trigger the system. Remember, the fusible links he removed that were installed last year? He zip-tied those to the conduit above the hand pull. We asked him why he did that as opposed to destroying them. He stated his company does this so the fire marshal can see that the links were replaced and they let the fire marshal destroy the old links. He mentioned that the code, NFPA 17A, requires the links to be destroyed but they leave them for the fire marshal.

The technician turned on the fryers and griddle under the hood and reset the tripping mechanism again (without the CO2 cartridge). He then tripped the suppression system. The fryer and the griddle lost power. He checked the breakers in the electrical room that fed power to these devices and they had tripped (an indication that the microswitch/interlock connected to the control box worked), and cut power to the cooking appliances. If there had been propane or natural gas fueled appliances, a separate interlock to a gas valve would have been provided and activated to shut the fuel supply off.

The technician checked the two handheld extinguishers. First, the K-Type, located near the cooking appliances, per NFPA 10, was visually inspected and recertified by the technician. Since he hydrostatically tested it last year, he did not need to visually inspect the inside of the cylinder this year as that is only required on a six-year basis.

Next, he inspected the ABC-type extinguisher. This one was due for its six year inspection. For this inspection, and in addition to the visual inspection, he dumped the chemical agent, disassembled the trigger and spraying components, and looked inside the cylinder. As he inspected both the exterior and interior of the cylinder he explained that he was looking for dents bigger than a ¼ inch, corrosion, and any other signs that the cylinder walls were damaged. He checked the valve and sprayer components for proper seating and functioning. When he completed his inspection, he reassembled the valve and sprayer  (taking time to lubricate the O-ring for proper sealing), refilled the cylinder with ABC chemical agent, attached the valve, pressurized the extinguisher (using nitrogen), and applied the appropriate inspection label and tag.

We asked him about continuing education requirements. The technician stated that his company provides several hours of continuing education throughout the year as well as sending their technicians to seminars and workshops.

The technician took a few more minutes to complete and review the paperwork before discussing his inspection and findings with us. He found a few issues that needed to be addressed but none that would cause him to “red tag” the system which he is prepared to do with each inspection, and has done so in the past at other customer’s operations. So, overall, the inspection went well for this business.

Overall, we found this technician performed a complete and thorough inspection, properly utilizing the applicable codes.  The system had also been properly maintained by the business.  Properly designed, constructed, maintained and inspected commercially cooking suppression systems greatly minimize the potential for a fire causing costly damage.

Applicable codes for commercial cooking suppression systems:
NFPA 17A -Standard for Wet Chemical Extinguishing Systems
NFPA 10 –  Standard for Portable Fire Extinguishers
NFPA 96 – Standard for Ventilation Control and Fire Protection of Commercial Cooking Operations

Founded in 1997, The Warren Group, forensic engineers and consultants provides technical investigations and analysis of personal injury and property claims as well as expert testimony for insurance adjusters and attorneys. Extremely well versed in the disciplines of mechanical, electrical, chemical, structural, accident reconstruction and fire and explosion investigation, our engineers and consultants are known for delivering the truth — origin, cause, responsibility and cost of an event or claim — with unmistakable clarity.

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