1. What the hood is actually built from
Most canopies, filter frames, grease cups and collection trays in commercial kitchens are stainless steel, and stainless is the easiest case: it tolerates heat, it tolerates alkaline degreaser, and it takes a rinse without consequence. The problems sit in what else is in the assembly.
Start by walking the hood and writing down, panel by panel, what each part is made of and how it is fixed. Aluminium appears in older filter frames, in some duct sections and in decorative trim; it looks like stainless until alkaline cleaner dulls it to grey. Powder-coated or painted steel is used on fan housings and on some duct casings, and heat plus a scraper will lift the coating off in patches. Galvanised sheet shows up in extract ducting that was installed by a mechanical contractor rather than a kitchen specialist. Gaskets, sealants, the foam in acoustic-lined duct, the insulation mat around a duct run, plastic louvres, drip-tray sight glasses, lamp holders, the seals on inspection doors and the gasket around a fire damper are all non-metal items that react differently to a hot wand.
Note the fixings as well. Peel-rivet joints, self-tapping screws into thin sheet, and pop-out filter frames are what a spray under pressure works on first. A joint that has been cleaned twice before with a cloth will open up the first time it meets a jet.
2. Which surfaces can take heat and which cannot
The commercial range hood grease removal decision is really two decisions: can this surface take hot, softened deposit being lifted off, and can it take the water that follows.
- Baffle filters and grease cups: usually stainless, and usually the thickest deposit in the room. Baked-on polymerised oil does not respond to cold detergent; heat softens it and pressure moves it. Soaking filters in a bath is the alternative when the frames are heavily fouled.
- Canopy interior and the filter rails: accessible stainless, safe to work, but the seams and the folded lips are where run-off collects, so the run-off has to be managed rather than allowed to fall into the cooking line.
- Canopy exterior and any decorative trim: the visible face is where an aggressive pass shows. Test on the least visible section first.
- Lights, cameras, switches and their bezels: wipe only. Nothing here is rated for a directed jet, whatever the surrounding steel is rated for.
- Duct interior and fire dampers: these are access and evidence questions before they are cleaning questions, and in a central kitchen they normally belong to a specialist duct cleaning contractor with inspection footage.
- Fan and motor housing: bearings, windings and terminal boxes do not take steam. Wipe the accessible casing and leave the assembly alone.
3. What to ask a supplier before a machine is specified
Suppliers of restaurant exhaust hood steam cleaning equipment will answer a specific enquiry much better than a general one. Ask for four things in writing, and put the answers in the same file as the hood register.
First, the working fluid temperature and how it is reached. A machine that produces low-pressure vapour at a low temperature is a sanitising tool, not a degreasing tool, and neither specification is interchangeable with the other.
Second, the delivery pressure and what the nozzle does at working distance, because pressure on a nameplate and pressure on a vertical baffle plate are not the same number once hose length, wand angle and a partly worn nozzle are in the line.
Third, whether the modes can be changed mid-task. On a hood the useful sequence is heat into the deposit, then a rinse once the film has released. A machine that gives one fixed output forces the crew to improvise with dwell time instead.
Fourth, what the manufacturer's own documentation says about the duty cycle and about the water supply. A fixed machine plumbed to a tap supply beside the wash point behaves differently from a mobile unit carried from a store cupboard several floors away, and a hood clean that runs out of water halfway through the second bank of filters is a clean that gets finished badly.
Ask the same supplier to state what their documentation does not cover. Any vendor who claims one setting suits every surface in a kitchen has not looked at your hood.
4. Running a trial on one bay before the whole hood is committed
Pick one bay at the end of the line, the worst deposit you can find that is still accessible, and run the trial there. Photograph it first, with something in frame for scale.
Then record four things during the trial rather than judging by eye afterwards: the working distance you actually held, the dwell time on the deposit before it released, the number of passes to get to bare metal, and the elapsed time from the last pass to a surface dry enough to go back into service. Those four numbers are what let you price the job across the whole hood, and they are what the second shift needs to repeat the result.
Check the trial area again the following day, once it has cooled and any residual moisture has gone. Lifted coating, dulled aluminium, an opened seam at a rivet line, and a filter frame that no longer seats flat are all findings that show up on the day after, not during the clean.
Run the hood and the extract fan afterwards and listen. A distorted panel or a filter sitting proud of its rail changes the airflow at the cooking line, and in a central kitchen that shows up as heat and smoke spillage in the servery.
5. Access, run-off, and the window you actually have
Map how the crew reaches the work. A hood above a long production line cannot be cleaned from a single position, and the route the machine and its hoses take across a live cooking area is a hazard in itself. Fixed installation at a wash point removes that problem for the parts that come off; a mobile unit from the PowerDe cleaning equipment range suits sites where the filters and trays are cleaned away from the line and the canopy face is worked in place.
Decide where the run-off goes before the wand moves. Degreased, oily water from a hood clean belongs in the site waste route through the grease interceptor, not in a prep sink and not in a floor drain beside the line. Say who checks the interceptor and how often it is emptied, because an interceptor that is already full turns a compliant clean into flooding across a production floor.
Write the window into the plan honestly: the time the crew needs, plus the time the surfaces need to be dry and the fan tested before the first production run. Less water left on the surface shortens that second part, which is the difference between finishing overnight and losing a morning of output.
6. Acceptance checks the crew can do without an argument
Do not write "clean" as the criterion. Write checks that hold up when a supervisor and a contractor disagree at two in the morning.
- A baffle filter held to light shows bare metal across its full width, with no varnish at the folds and no residue blocking the drain slots.
- A hand run along the inside of the canopy lip finds no soft deposit and no standing water.
- Every filter frame seats flat with no gap at the rail, and no panel is distorted.
- Grease cups and the collection tray are refitted with their seals intact, not left out to dry.
- The extract fan runs without new noise or vibration, and smoke or steam is captured at the cooking line rather than drifting into the servery.
- Nothing electrical is left damp: lamp housings, switch bezels and camera mounts are dry and refitted.
Keep the signed sheets, the interceptor records and any duct inspection footage together. Deep grease deposits in extract systems are a fire matter as much as a hygiene matter, and the record of what was cleaned, when and to what standard is what a fire risk assessor asks for.
7. What to send if you want a configuration matched to your hood
Shenzhen PowerDe Automation Precision Equipment states that it publishes the parameters of its Cleaning Equipment Series machines, and customized steam cleaning equipment can be requested against a site layout and cleaning duty rather than chosen from a catalogue page.
Send three things with the enquiry, and you are more likely to get a configuration than a brochure: the material list you wrote while walking the hood, photographs of the worst deposit with something in frame for scale, and the overnight window you can actually offer. Then ask the supplier to state plainly which parts of your hood their documentation does not cover, and trial one bay against the acceptance checks above before the whole extract system is signed off.
