What hood certification is
Hood certification is a separate procedure from hood cleaning. Cleaning is what we do quarterly with a degreaser and a brush. Certification is a once-a-year test, on a different ticket, that confirms the hood's capture and containment — that is, its ability to capture grease-laden vapor over the cooking surface and contain it within the plenum without spilling into the kitchen breathing zone — meets the NFPA-96 performance criteria.
What we use
Two tools. A smoke pencil — a hand-held wax-stick smoke source whose plume reads pressure direction at the hood lip — and a SmokeGen portable smoke generator that lays down a heavier visible smoke at the cookline. The smoke pencil reads the corner conditions; the SmokeGen reads the centerline.
What the test looks like
We bring the cookline up to a representative steady-state load (or the operator does, with a couple of pans of water on a high boil). We circulate visible smoke at six positions along the cooking surface — four corners, two centerline — and observe whether the plume is captured into the plenum within three seconds at each position. Three seconds is the working benchmark, drawn from ASHRAE 154-2024's Annex B.
Fail conditions: any position where smoke escapes the hood envelope into the breathing zone; any position where capture takes longer than five seconds; any position where the side-curtain spillage is visible at standing height. A failed test is a flag, not a sticker. A flagged hood gets a corrective action plan and a re-test on a separate ticket.
What gets stickered
Each hood that passes gets a 4×4-inch sticker on the side wall of the hood, dated and serialized. The serial ties to a digital record in our system. The sticker is what an inspector looks at first.
What can fail a hood
Most failures are makeup-air problems. The hood is designed to pull a calculated CFM under a specified static pressure differential between the hood plane and the dining room. If the makeup-air unit is undersized, mis-belted, or stuck on a bad damper, the hood will fail capture-and-containment even when the hood itself is in perfect shape. This is why makeup-air balancing is on the seasonal cycle and not the annual one.
Other failures: filter rack out of square so filters do not seat fully; side-curtains too short for the cookline; an exhaust fan motor that has slipped enough belts to be operating at 80% of nameplate. We will not paper over any of these.
What it costs
$240 for the first hood, $180 for each additional hood on the same kitchen, on a single visit. The certification visit is scheduled at least four weeks after the most recent cleaning so we are testing the hood, not the day-after sheen.