THE PHYSICS OF A HOOD FIRE
When grease burns on your range, vaporized particles rise with the heat plume into your exhaust system. Day by day, these particles cool and deposit on every surface they touch - baffle filters, hood canopy underside, duct walls. What starts as a film becomes a coating. What becomes a coating becomes a layer. Layers become centimetre-thick grease deposits that are functionally fuel.
A minor flame flashback or a grease fire on the cooktop sends superheated gas up through the hood. In a clean hood, that dissipates. In a grease-clogged hood, it ignites. The fire travels through your ductwork into your ceiling void within seconds, bypassing your cooking equipment suppression system entirely.
⚠ Insurance Warning
Most commercial property and general liability insurance policies require documented hood cleaning in accordance with NFPA 96. A fire claim filed with no cleaning maintenance records may be denied. Ask your broker about your policy's cleaning compliance requirements.
GREASE ACCUMULATION BY ZONE
Understanding where grease accumulates fastest helps you understand why professional cleaning matters - and why it must cover every zone, not just the filters.
Baffle Filters
The first line of capture. Designed to be removed and cleaned, but most kitchens only clean filters - and leave all the following zones untouched.
Hood Canopy Interior
Grease drips and coats every internal surface. Most kitchens never touch this. When ignited, this zone flares first and fastest.
Plenum Chamber
The collection chamber above the filters. Liquid grease pools here. In a fire, this pool becomes a fuel reservoir that feeds directly into the duct.
Duct Entrance & Transitions
The zone where duct changes direction accumulates the most grease. This is the most dangerous area and the hardest to access.
GREASE TRAPS: THE OTHER PROBLEM
Exhaust hoods get most of the fire-risk attention, but interior grease traps (also called grease interceptors) create a different but equally serious problem. Located in or near the dishwash and prep sink plumbing, they collect fat, oil, and grease from washing. Without regular cleaning, they:
- Overflow into the main drain system, causing blockages and potential sewage backup
- Create powerful odours that spread through the kitchen and dining area
- Violate municipal bylaw - Edmonton and surrounding municipalities regulate grease trap maintenance
- Attract pests, particularly cockroaches and drain flies
THE KL CLEANING HOOD PROCESS
Our hood cleaning process treats the entire system - not just the visible surfaces.
Filter Removal & Soak
All baffle filters removed and soaked in commercial alkaline degreaser before any other work begins. This is the only way to actually clean filters.
Plenum & Canopy Interior
Full chemical application to hood canopy interior and plenum chamber. Dwell time observed. This is the zone most other cleaning services skip.
Duct Entrance Treatment
Duct entrance and transition zones treated as far as accessible. This is the highest-risk zone and requires specialized tools and chemistry.
Hot Pressure Rinse & Capture
All surfaces hot-pressure rinsed. Grease and chemical run-off captured - never allowed to drain onto kitchen floor or into the cooking equipment below.
Filter Reinstall & Documentation
Clean filters reinstalled and correctly seated. Service record produced with date, scope, and products used - critical for insurance compliance.
See also: stainless restoration · floor degreasing · health inspection checklist · cleaning frequency guide
