Commercial Kitchen Type I Exhaust Hood Monthly Grease & Suppression Nozzle Inspection Log

ContextRemove filters one at a time and hold each over a catch tray before pulling fully free — a heavily loaded filter drips aggressively when tilted. Inspect the grease-laden face while in hand: a uniform light-to-medium coating across the filter surface is normal for a standard monthly service cycle. A thick, dark, nearly solid layer of polymerized grease indicates either the previous cleaning was incomplete or that cooking volume has significantly increased since the prior cycle. Test rigidity by pressing lightly on the mesh: a filter that flexes noticeably or feels soft at any point has had its structural integrity compromised by prolonged grease saturation and must be replaced, not cleaned and reinstalled. Record the position of each filter (e.g., left, center-left, center-right, right) in the log — grease distribution across positions often reveals equipment hot spots or airflow imbalances invisible without positional tracking.

ContextMost AHJs (authorities having jurisdiction) and suppression contractors use 1/8 inch as a practical accumulation threshold that triggers an accelerated cleaning schedule when measured on baffle filter surfaces. Draw your putty knife edge in a single pass across the flat filter face and observe the displaced material. Polymerized — hardened or dried — grease indicates long-duration accumulation and requires a degreaser soak rather than standard hot-water washing; it also confirms that airflow restriction through the filter has been building progressively, reducing capture velocity at the hood face. Record depth as a range observed across the filter area rather than a single-point measurement — for example, "1/16 to 3/16 inch" — so the log reflects the actual distribution rather than a cherry-picked low reading.

ContextWith filters removed, direct your flashlight into the rail or channel that holds each filter in the hood frame. These channels are a persistent accumulation site that is almost never cleaned during routine filter service because they are visually inaccessible while filters are in place. Grease pooling in seating channels represents a fuel-near-heat scenario in an area that suppression nozzles may not directly cover — the system's design intent is to protect the cooking surface hazard zones, not the channel interior. Inspect each locking tab, retention clip, or handle for deformation or cracking: a filter that shifts laterally or falls out of position during a fire event or suppression discharge can redirect a flame front directly into the plenum interior.

ContextThe drip tray collects liquid grease that passes through or drips from the baffle filters. Measure this volume consistently — by weight on a digital scale converted to fluid ounces, or directly in a graduated container — and record it in the log. Tracking this number month over month creates a meaningful trend line: a sudden 40 to 60 percent increase in collected volume typically signals a new high-fat menu item, a change in cooking method, or a filter that was returned to service without a full cleaning in the prior cycle. If the tray overflows between monthly inspections, the current collection interval is inadequate — an overflowed tray deposits grease directly onto the plenum floor, which the suppression system is not designed to manage as a standing fuel source.

ContextPress along the tray bottom with moderate hand pressure to confirm no low spots have developed that pool grease away from the drain opening. Carbon buildup and polymerized grease can completely seal a drain opening that appears clear from above; use your scraper tip to confirm the drain channel is fully open. Deformation or warping — common in high-heat installations — can cause the tray's effective low point to migrate toward the rear plenum wall rather than the intended drain outlet, which positions accumulated grease directly below or adjacent to suppression nozzles. Verify that all retaining clips or fasteners are fully engaged and that the tray makes full contact with the seating lips on both sides with no visible gap.

ContextThe plenum is the chamber between the baffle filter plane and the duct collar. With filters removed for unobstructed access, systematically scan the rear wall, the plenum ceiling, and both side walls using your flashlight. A thin, even film that wipes off cleanly with a cloth is an acceptable monthly finding. Any grease that pools on horizontal surfaces, drips from overhead surfaces, or resists removal with moderate wiping requires an immediate unscheduled cleaning before the next cooking service — NFPA 96 §11.4 establishes that accumulation exceeding approximately 1/8 inch on horizontal plenum surfaces represents a frequency-of-cleaning trigger, not a note-and-monitor situation. Always inspect the corners and seams between plenum surfaces last, after scanning the flat areas, as turbulence in the exhaust airstream causes grease to accumulate faster at these junctions.

ContextCarbon buildup or any discoloration that cannot be explained by normal grease staining — which is typically tan-to-brown, not black — indicates that combustion products have entered the plenum. This means either that cooking equipment flame patterns are contacting grease accumulation, or that a suppression system discharge has already occurred without staff awareness. Older systems without automatic fire department notification can discharge and reset without leaving visible evidence to kitchen staff. Any finding of scorching, carbon streaks, or burn patterns must result in immediate cessation of cooking operations and a call to your licensed suppression contractor before service resumes. Do not simply clean the deposit and continue — the source of the combustion event remains unresolved and will recur.

ContextThe junction where the plenum transitions to the duct collar is a natural low point in many hood configurations. Angle your inspection mirror into the duct opening and look for a visible grease pool or a drip ring around the duct collar interior. Even a thin but continuous drip ring indicates that grease is regularly reaching the duct interior and that the duct system will show significant accumulation beyond the visible first section. Per NFPA 96, the entire duct system — not just the hood — must be cleaned at intervals sufficient to prevent the level of accumulation visible at this junction; a significant collar finding cannot be adequately addressed by cleaning the plenum alone.

ContextEach nozzle orifice is fitted with a foil, plastic, or rubber protective cap that prevents grease vapor from infiltrating and occluding the orifice between inspections. Cross-reference your count against the system design drawing or the certification tag mounted inside the hood — depending on the cooking equipment coverage layout, your system may have anywhere from four to ten or more nozzles. A missing or displaced cap means the orifice has been exposed to grease-laden air, and the nozzle must be inspected by your suppression contractor to determine whether occlusion has occurred before the next service. A clogged nozzle will not discharge at the design flow rate, leaving its coverage zone unprotected during a fire event. Do not attempt to replace a missing cap with improvised material — even a physically fitting substitute may not provide the design seal, and any field modification to a suppression system component constitutes a code violation.

ContextThe system design drawing specifies the required discharge angle and target surface for each individual nozzle — typically aimed at the cooking surface hazard area (fryer vat, char-broiler grate, open-burner range top) at a specific distance and angular orientation. Pull out the drawing and compare each installed nozzle against its specification. A nozzle that has been bumped, rotated, or shifted will deposit wet chemical agent in the wrong area during a fire discharge — even a 10 to 15 degree deviation from the design angle can shift the effective coverage plume by several inches at discharge range, potentially missing the target hazard entirely. If you do not have the system drawing on hand, do not estimate nozzle positions as acceptable; contact your suppression contractor for a copy and defer the nozzle position assessment until you can make an accurate comparison.

ContextShine your flashlight directly at each nozzle face and look for brownish grease discoloration, a visible surface film, or any apparent narrowing of the orifice opening. Vapor infiltration can occur even when the protective cap appears intact, due to minor seal degradation over time. Any visible fouling must be reported to your suppression contractor — do not attempt field cleaning of a nozzle orifice. The orifice geometry is precision-manufactured and any abrasion or mechanical contact can alter the discharge pattern in ways not detectable by visual inspection. Your suppression contractor will determine during their semi-annual service whether nozzles require flow testing to verify that discharge performance has not been degraded by the observed fouling.

ContextEach suppression nozzle is positioned at a specific distance and angle above its target cooking hazard as specified in the system design drawing. When cooking equipment is replaced, moved, or supplemented after the suppression system was originally installed, the nozzle coverage geometry may no longer match the actual hazard location. A nozzle intended to suppress a fryer at 8 inches of standoff distance that now sits 3 inches away due to equipment repositioning will discharge wet chemical agent directly into hot cooking oil at a steep angle, potentially causing a violent splatter reaction that spreads burning oil rather than suppressing it. Visually compare each cooking appliance position against the system drawing; any discrepancy must be reviewed by your suppression contractor before continued operation.

ContextFusible links are the passive heat-detection mechanism that triggers automatic suppression system discharge. They consist of two metal pieces joined by a solder alloy formulated to melt at a precise temperature — typically 165°F for standard cooking equipment, 212°F for high-output broilers and salamanders, or 280°F for solid fuel equipment. A coating of grease on the link surface acts as thermal insulation, raising the effective trigger temperature and delaying system activation during a fire event. Gently wipe each link with a clean, dry cloth — do not apply solvents, lubricants, or any mechanical force that could distort the link geometry. If any link shows corrosion pitting, visible bending, stretching, or physical deformation, it must be replaced immediately; fusible links are not field-repairable under any circumstance.

ContextEvery fusible link carries a stamped or tagged temperature rating that should be documented in your system design records and the suppression contractor's service reports. Standard open-burner ranges and fryers require 165°F links; high-output char-broilers typically require 212°F; solid fuel cooking equipment requires 280°F or higher. A link with an incorrect rating installed at the wrong position will either activate too readily under normal high-heat cooking conditions — causing a nuisance discharge that wastes the agent charge and forces a shutdown — or will fail to activate until temperatures far exceed the design fire scenario, allowing the fire to grow beyond suppression capacity. If link ratings are absent from your current documentation, request a full link audit from your suppression contractor at the next scheduled service visit.

ContextThe fusible link is held in tension by a stainless steel cable that connects the link to a spring-loaded actuator. When the link melts at its rated temperature, the cable tension releases and the spring drives the actuator to discharge the suppression system. Inspect the cable for visible slack — a cable that droops between connection points rather than running taut will not reliably transmit the spring force when the link melts. Examine the crimped fittings at both cable ends for corrosion on the crimp body, visible fraying of individual cable strands emerging from the crimp, or any white or green oxidation deposits. Cable fraying is an immediate contractor referral, not a monitor-and-recheck finding; a frayed cable can separate before or during a fire event, leaving the suppression system unable to self-activate.

ContextThe wet chemical agent cylinder has a pressure gauge at the top of the cylinder body. The needle must fall clearly within the green acceptable-pressure band — not touching the yellow caution zone and not anywhere in the red low-pressure zone. A reading outside the green zone means the system may not discharge at the design flow rate and pressure, potentially leaving the protected cooking hazard with insufficient agent coverage during a fire event. Ambient temperature extremes in the cylinder storage area can cause gauge pressure fluctuations; if the cylinder is in a space that experiences significant seasonal temperature variation, consult the manufacturer's specification sheet for the acceptable operating temperature range and compare it to the current conditions. Never attempt to re-pressurize the cylinder independently — this requires specialized equipment and is strictly contractor work.

ContextExamine the full height of the cylinder for dents, deep scratches, or visible deformation in the cylinder wall. Check around the valve head assembly and at the cylinder base for any yellowish-brown residue, which is the characteristic staining left by a slow wet chemical leak. Even minor seepage means the agent charge is being depleted and must be addressed by the contractor before the next cooking service. A dented cylinder is not a cosmetic concern — wet chemical cylinders operate at significant internal pressure, and a structurally compromised cylinder represents a rupture risk. Confirm that the cylinder is firmly secured in its wall mounting bracket and shows no movement when you apply moderate hand pressure; a cylinder that shifts on its bracket stresses the piping connections and can eventually cause agent loss.

ContextThe manual pull station allows kitchen staff to trigger the suppression system manually if automatic activation fails or is delayed. The safety pin prevents accidental activation during normal operations. A tamper indicator — typically a thin wire seal or a plastic pull-tab across the handle — confirms that the safety pin is fully engaged and the handle has not been disturbed since the last inspection. A broken or missing tamper seal requires investigation: it may mean the pin was accidentally removed during cleaning, or that someone tested the handle without authorization. In either case, the contractor must verify the pin is correctly installed and replace the seal. Separately confirm that the pull station is identified by clearly posted signage visible from the primary cooking stations, and that at least two currently employed kitchen staff can locate and operate it without guidance.

ContextFull ductwork inspection requires access panels and is the domain of your scheduled professional cleaning service. However, the first 12 inches of duct visible from the plenum opening provides a reliable proxy for the duct system's overall condition. Look for flowing grease, heavy deposits along the duct bottom, or a visible pool at the base of the collar. NFPA 96 requires that duct systems be cleaned at intervals sufficient to prevent accumulation exceeding 1/8 inch in heavy-use kitchen configurations. If significant grease is visible at the accessible duct entry during a monthly inspection — anything more than a thin even film — the full duct system is overdue for professional cleaning and an unscheduled service should be requested before the accumulation reaches the exhaust fan housing.

ContextWith the exhaust fan running at normal operating speed, listen for any grinding, squealing, rattling, or high-pitched bearing noise not present during the previous monthly inspection. Grease accumulates on fan blades in an asymmetric pattern that progressively unbalances the fan wheel, eventually generating resonance vibration that accelerates bearing wear and can loosen the fan housing from its mounting structure. Vibration also works duct joints downstream progressively looser, creating gaps through which grease vapors can escape into building structural spaces above the ceiling. Any new, reproducible noise or vibration that you can describe specifically must be logged and assigned to maintenance for assessment before the next cooking service period — not the next monthly inspection.

ContextMany exhaust fan housings include a dedicated grease drain or removable collection cup. Confirm whether this component has been emptied and cleaned as part of your current scheduled maintenance program. An overflowed fan housing allows grease to contact motor windings directly, creating an electrical fire risk that is separate from and independent of the cooking surface hazard. Grease can also exit via the exhaust discharge onto the building roof, where it accumulates near roofing materials and constitutes both a structural fire hazard and a potential code violation. If the fan housing has no integral drain and you observe grease pooling inside through an access panel, add an unscheduled fan assembly cleaning to the corrective action log.

ContextType I hoods require balanced make-up air to maintain the designed capture velocity at the hood face. Make-up air supply vents are frequently blocked in active kitchens by stored equipment, cardboard delivery boxes, or portable shelving pushed against walls during service. An obstructed make-up air supply shifts the pressure balance and degrades capture velocity even when the exhaust fan is operating normally at its design speed. The visual evidence of a compromised make-up air balance typically does not appear at the hood itself — it shows up on the walls and ceiling surfaces outside the hood canopy, where grease deposits and moisture staining develop progressively over weeks of operation with insufficient makeup air compensation.

ContextHold a tissue or a six-inch strip of lightweight paper at the leading edge of the hood canopy at the height of the cooking surface. The tissue should be drawn firmly and consistently toward the hood face by the exhaust airflow with no sideways flutter or reversal at any point. If the tissue moves sideways or away from the hood at any location along the canopy edge, capture velocity is insufficient at that point and cooking vapors are escaping into the kitchen environment. Escaping vapors increase grease deposition on all surfaces outside the hood canopy, raise the ambient kitchen temperature, and can trigger smoke detector nuisance alarms from combustion byproducts. Document any failure with the approximate canopy position where it occurred and engage an HVAC technician to perform a full airflow balance measurement.

ContextEvery field in the log must contain a specific, measurable entry. Log grease depth as a range in fractions of an inch per zone: front baffle, rear plenum wall, plenum ceiling, and duct collar junction. Log drip tray volume in fluid ounces or milliliters. Log nozzle cap status as a count — for example, "8 of 8 caps intact" — rather than a binary pass/fail. Record fusible link condition by position number with a brief specific note for each, such as "Link 3 — light grease film wiped clean, no visible deformation." Record the cylinder gauge reading as a numeric value if the scale is graduated, or as a clear zone description if not. Include the exact inspection start time and the full printed name of the inspector. If photographs were taken, number each photo and cross-reference the photo number against the relevant log field.

ContextA finding with no assigned owner and no deadline is functionally unresolved, regardless of how it is written in the log. For each discrepancy, record: the exact nature of the finding, the specific corrective action required, the full name of the responsible individual, and a required completion date. For any finding involving a suppression system component, the deadline must be within 24 hours or before the next cooking service, whichever is sooner. For cleaning deficiencies, the deadline must reflect the standard that the deficiency cannot recur at the next monthly inspection. When the required action must be performed by a licensed contractor, enter "Contractor required — [service company name] contacted on [date]" and follow up to confirm scheduling within your suppression service agreement's required response timeframe.

ContextThe inspector's printed name and signature on the completed log certifies that the inspection was conducted in good faith and that all entries accurately reflect observed conditions. File the log immediately upon completion — not at the end of the day or end of the week. Most AHJs require a minimum of 12 consecutive months of inspection logs to be accessible on-site at all times; during a formal compliance audit, records going back 36 months may be requested. Digital filing of scanned PDFs is accepted by most jurisdictions, but confirm your local fire marshal's current policy before transitioning away from paper originals. A single missing month in the inspection record is a compliance flag that can result in a formal notice of violation even when all other records are complete and thorough.