Kitchen pipework gets cleaned last, after the line, the floor and the filters, because nobody owns the outside of the extract duct, the sprinkler branch above the pot wash or the water pipework behind the prep benches. That is where overspray becomes the whole problem rather than a side effect: steam and degreaser that leave the target surface land on dry goods, on the wall tile, on equipment that has already been cleaned, and on the floor below, and the crew spends the rest of the shift undoing what the nozzle just did. Reducing overspray is not about buying a gentler machine. It comes from five decisions made before the wand is lifted — what is being cleaned, which mode is in use, how far the nozzle stands from the pipe, where the run-off is going, and who is holding the wand.
Split the pipework into two jobs before choosing a method
“Clean the pipes” covers two different soils with two different causes of overspray, and a single method applied to both produces waste twice over. Grease-laden extract pipework — the hood canopy, the duct above it, the fan housing and the first duct section — carries polymerised oil that needs heat to release, and because the deposit is thick, operators compensate by holding the nozzle closer and moving slower, which is exactly when the plume of steam and loosened oil spreads sideways. Service pipework — water supply and waste pipes, gas runs, sprinkler branches, cable trays and the supports and hangers that hold them all up — carries dust, airborne kitchen grease and dried splash. It is a thin, loose film that a short pass and a wipe will take off, yet it is the pipework most often soaked, because nobody has written a method for it.
Write the two onto separate lines of the work order, and state what each one is allowed to be wetted with. Extract pipework gets the heat. Service pipework gets the shortest pass that lifts the film, and most of it never needs a wet steam mode at all.
Choose the mode before the nozzle leaves the hook
Most overspray in a kitchen is free water that has been turned into a cloud and directed at a surface that did not need it. Machine pages in the PowerDe cleaning equipment range describe switching between dry and wet steam, and that switch is the single control staff have over how much moisture reaches the pipe. Dry steam carries little free water: it puts heat into a deposit without leaving a wet trail behind the nozzle, which is what you want on overhead surfaces, on pipework that runs above a counter or a sink, and around the electrical and control parts mounted on cooking equipment. Wet steam carries more moisture and more heat volume, which suits the heavy deposit on a baffle filter, the underside of a hood canopy and a floor drain channel — surfaces where the next step is drying or recovery anyway.
Put the mode against each surface in the written method, not in the operator's judgement. A crew told to “use steam on the duct” will use the wet mode because it looks like it is working, and the ceiling tiles, the lighting and the pipework either side of the pass will absorb the result. A crew told “dry mode on overhead pipework and services, wet mode only on the removed filter panels and the canopy underside at the end of the pass” produces a controllable amount of moisture and can be corrected when it does not.
The same reasoning applies below the pipe. A central commercial kitchen degreasing machine such as the fixed PowerDe HW02 is listed on its detail page with a 220 V supply, 6 kW heating power, 160° steam temperature, 0.8 MPa vapour pressure and an 80 L SUS304 tank. Those figures decide how much of the pipework one operator can do before the machine has to recover, and they should be checked against your own supply voltage and water point in writing before the method is signed off — published figures on product pages are not always consistent across the site, and the machine you buy is the one whose specification sheet you keep.
Distance, travel speed and passes are the actual controls
Overspray is produced by geometry, not by care. Bring the nozzle closer to recover a stubborn patch and the plume widens; slow the pass down and the vapour that has already been generated has more time to settle on whatever is behind and below the operator. The two settings that decide how much material leaves the target are the working distance and the travel speed, and the third is the number of passes over the same length of pipe.
Write all three into the pipework method as numbers, in the form an operator can follow on a ladder with gloves on:
- A working distance for each class of surface — one for the duct exterior and one for the canopy underside — held constant for the whole pass rather than closed in when a patch looks dirty.
- A travel speed expressed in a way a person can hold, such as a slow walking pace along the pipe run, and a maximum dwell on one point.
- A permitted number of passes on the same section, and what to do on the second pass instead of the third: back off with a brush and a wipe rather than another blast of steam.
- The direction of travel along the pipe run, so steam is worked away from clean surfaces and away from the end of the line where dry goods are stored.
The most common cause of a ruined clean above a cooking line is an operator closing the distance because the deposit is thick. The answer to a thick deposit is dwell and heat, or removing the section and cleaning it at a wash point — not a nozzle moved closer to a surface that is over food.
Protect the room before the wand is lifted, not afterwards
Anything within the plume will be wetted, so the run has to be emptied rather than worked around. Before steam is generated above a line: remove or completely cover dry goods, packaging, open containers and anything on open shelving; cover the cooking equipment below, including control knobs, terminals, indicator lights and any gas ignition assembly, and mark those items as wipe-only on the method; cover or shut the fryer and griddle wells so run-off cannot fall into hot oil; and put a drip line under the pipe run being cleaned.
Sign the end of the line and the floor beneath it, and keep people out of the area while the pipework is wet — this is a scalding control as much as a cleanliness control. Where the kitchen cannot be emptied of equipment, clean the pipework in shorter sections so the covered area stays small enough to be managed by one person, and plan the section so it finishes at a wall or a support rather than in the middle of a run above an uncovered counter.
Capture the run-off, or the overspray is only being relocated
What drips off a cleaned pipe is the part of overspray that is measured later, in the form of a blocked interceptor, a slipped contractor or a health inspection note. Greasy run-off from pipework belongs in a tray, a recovery vacuum or a floor drain that feeds the site's grease interceptor — never in a prep-area sink, never in a surface drain that discharges to a foul or rainwater system without that route being confirmed for the site.
Practical controls that work above a cooking line:
- A tray or a length of plastic sheeting taped under the pipe section, large enough to catch the drip line plus a margin, with the run-off collected into a bucket rather than allowed to pool on the sheet.
- A vacuum attachment used immediately behind the nozzle on overhead work, so the loosened material is taken up rather than allowed to fall and re-deposit further along the run.
- One operator on the wand and one on the wipe, working as a pair — a single person cleaning overhead pipework cannot both direct the nozzle and hold the surface dry, and the second pair of hands is what reduces the wetting distance.
- Interceptor checked and emptied before the pipework job, not after it, because a full interceptor turns a compliant clean into a flood on the kitchen floor.
Match the machine to the pipe run, so nobody is dragging a hose overhead
Reach is an overspray control, because a hose that cannot stretch is pulled across clean work, and an operator stretched out along a pipe run cannot hold the nozzle at a fixed distance or a steady speed. Where there is a permanent water and power point near the kitchen line, a fixed machine sits at that point and the wand does the travelling, so check the socket and breaker rating, the water point and thread, and the distance from the point to the far end of the pipe run before deciding the configuration is workable.
Where pipework runs through several areas — a servery corridor, a scullery, a back stair, a second prep room — a machine that has to be dragged between them will be cleaned less often and cleaned worse, so a mobile unit from the Cleaning Equipment Series with battery power is the practical answer. Those units are offered in versions listed with and without a battery, and where the battery is not supplied the site has to source a compatible one — a real cost and a real delay if it is not confirmed before ordering. Ask for the hose length, the wand length and the nozzle set on the specific model you are being quoted, and check that a person can walk the full pipe run with the hose behind them without crossing an aisle.
Ask what the machine does when the tank empties mid-job. The fixed HW02 page lists leakage, short-circuit, high-temperature, high-voltage, water-shortage and high-voltage-explosion protections; list them item by item on your own risk assessment, confirm the set for the exact model you are buying, and write into the method which staff member resets what and when a tripped machine is reported rather than restarted during service. Those items protect the operator and the machine, not the pipework above the counter.
Train against a written standard and check it on the pipe
Nobody reduces overspray by being told to be careful; they reduce it against a standard they can see. Set up a training run on one section of pipework that nobody minds getting wet, and work through the settings: the mode, the distance, the speed, the number of passes, and where the run-off lands. Photograph the covered area before the pass and the floor after it — the photographs are the lesson, and the operator who sees their own drip line on the floor will correct it without being told.
Then put four checks against every pipework task, phrased so the answer is obvious in seconds:
- Nothing wet that was not on the cleaning list — a walk of the run with a hand over the covers, shelving and equipment below.
- No visible grease film returning at the joints, seams and the underside of the canopy, where an over-wet pass leaves a streaked line.
- Floor dry within a metre of the work area before the line is reopened.
- Drip tray and interceptor accounted for, with the recovery recorded on the same sheet as the clean.
Keep the completed sheets with the dates, the operator and the checker named. A kitchen that can show which section of pipework was cleaned, with what method and to what result, is in a different position when an insurer, a fire risk assessor or an environmental health officer asks about grease deposits and extract systems.
Where overspray cannot be controlled with the tools on site
Some kitchens have pipework layouts that defeat any careful method: a duct run above a fully open servery that cannot be cleared, a basement extract line with no access except from below across a working counter, or a long pipe run with no water or power point anywhere near it. In those cases the fix is a configuration rather than a technique. Shenzhen PowerDe Automation Precision Equipment lists customised configuration and technical support alongside its equipment range, and its solutions page covers specifying equipment against the site's actual conditions. Send a photograph of the pipe run, the cleaning window you can allow, the power and water available at that point, and the list of surfaces that must not be wetted, and ask for a method and a machine matched to that layout rather than accepting the nearest catalogue model.
Until that configuration exists, reduce the scope: clean pipework in shorter sections, clean the extract line more often so the deposit never reaches the thickness that tempts an operator to close the nozzle distance, and leave service pipework to a dry-mode pass and a wipe. Overspray is almost always a symptom of a job that was written too broadly.
