Kitchen extract systems create a second waste stream that most cleaning schedules never mention. Every fryer, griddle, charbroiler and tilt kettle in the kitchen throws oil vapour into the air, and that vapour condenses as a film on the canopy, the duct walls, the centrifugal fan wheel and the grease interceptor. By the time the deposit is visible it has been accumulating for months, and the crew has no record of how thick it has become or how quickly it is growing. Wastewater handling is the discipline that stops that work from flooding the kitchen, loading the interceptor and washing grease and detergent residue into a drain the site is not permitted to use. The checks below are the ones to put in front of a supplier before any machine or contract is signed.
1. Map where the run-off is allowed to go
Ask the supplier to walk the kitchen and mark, on a drawing, every point where water will be applied and every route the run-off will take. The answer decides more than the cleaning method. A canopy cleaned in place above an active servery sends water down the face of the equipment and across the floor; the same job cleaned in a wash bay sends it into a strainer and an interceptor. Where the only drainage is a surface drain in a prep area, in-place cleaning of the canopy and upper duct has to be ruled out, and the plan changes to panels removed and cleaned off the line.
Get that drawing signed by whoever owns the drainage on site. A supplier who will not put the route on paper is planning to improvise it in front of the chef on the night.
2. Ask for the water volume per task, not per machine rating
Any supplier will tell you a machine is efficient. Ask instead how many litres leave each task on the wet side: one canopy, one metre of accessible duct, one fryer bank, one floor section. Write the number against the task. Water volume is what determines tank size, how many fills a shift needs, whether a plumbed unit is workable, and how much run-off the interceptor has to absorb in one sitting. A figure quoted as a machine rating tells you nothing about the job.
The distinction matters when you compare options. The [Fixed Steam Cleaning Machine PowerDe HW02](https://www.powerde.net/qingjiehangye/41.html) is a 220 V unit with an 80 L stainless tank and a tap-water inlet, so it draws from a water point and carries its own buffer between fills. A [mobile steam cleaning machine](https://www.powerde.net/qingjiehangye/) from the same Cleaning Equipment Series travels to the work. Which one fits depends on where your water points are and how far the crew has to move. Ask both suppliers for litres per task and their fill plan, then compare.
3. Match the steam mode to the deposit so less water reaches the floor
Grease in an extract system is not one deposit. Fresh grease is soft and moves with warm water and detergent. Varnished, polymerised grease on an oil well or a fan wheel will not lift with water alone; heat has to soften it before pressure moves it. Ask which mode the supplier uses for which surface. A [dry and wet steam cleaner](https://www.powerde.net/qingjiehangye/41.html) lets the crew drive heat into a baked-on film with the drier mode, then switch to the wetter mode as a rinse once the film releases. That sequencing is a drainage point as much as a cleaning one: drier modes leave less water on the surface, so run-off is smaller and the equipment is back in service sooner.
The HW02 product page lists 6 kW heating power, 160 °C steam temperature and 0.8 MPa vapour pressure, and it describes dry steam and wet steam as the two working modes. Ask the supplier what dwell time and how many passes they apply to your worst deposit, and ask to see that on a trial. If the method produces a sheet of water running to the drain on the first panel, it is the wrong method for your drainage.
4. Demand containment before the wand is switched on
Ask what the supplier brings to stop run-off, and check that it appears on their equipment list rather than in a sentence of method copy. The working minimum: trays or bunded channels under the canopy edges and duct joints; absorbent granules or mats at the foot of the run; disposable sheeting taped over sockets, controls and any open food handling; a dedicated collection vessel for the grease scraped off before any water is applied; and a named person whose job it is to watch the drainage while the wand is live.
Scraping first is not optional. Grease removed by hand and bagged as waste never becomes an emulsified load in your drain. Any supplier whose method starts with water on a thick deposit is moving a disposal problem into your drainage system, and it is your drainage they are using.
5. Interceptor and trade-effluent responsibilities in writing
Ask, before the job: who checks the interceptor level before cleaning starts, who pays for emptying if the cleaning fills it, and what the site's consent limits are for discharge to the public drain. Grease-laden, hot, detergent-bearing water discharged outside those limits is the site's liability, not the contractor's, whatever the contract says on the day. Ask the supplier to state in their method the maximum volume they intend to discharge and how they will keep run-off inside your interceptor and drainage.
Also ask what happens to the solid waste. Scraped grease is a waste stream with its own disposal route; a supplier who leaves it bagged in your bin store has handed you a fire load and a smell. Get the removal of that waste in the same paragraph of the quotation as the cleaning.
6. Trial on your worst deposit and measure what you get back
Do not buy on a specification sheet. Ask one or two suppliers to clean one panel, one accessible duct section and one fryer well on your own site, and judge three things. Whether the deposit released without a sheet of run-off across the floor. How long the equipment and the floor took to return to dry and usable. What the crew can repeat the following week without that supplier present.
Put a stopwatch on the return-to-service window and write the number down. That figure decides whether cleaning can happen after service in a single evening, which is usually the only window available. Timing it during a trial lets you build the schedule around a measured result rather than a promise.
7. Training, handover and who maintains the machine afterwards
Ask what training comes with the equipment and who is trained. The crew doing the work at two in the morning needs the working distance, dwell and pass count for your worst surfaces written down, not remembered by one supervisor. Ask also who services the machine: heater scale from hard water quietly reduces output long before a unit fails, so a descaling routine with a named owner belongs in the handover along with the spares list.
The HW02 product page describes leakage, short-circuit, high-temperature, high-voltage and water-shortage protection, and earlier blog records for the same unit list five protections — the published pages do not agree on a count, so treat the items rather than the number and ask the supplier which protective trips the unit has. Any crew with a machine that trips one of them needs one instruction: report it, do not reset it repeatedly through a shift.
8. Records the site can produce on demand
Deep grease deposits in cooking equipment and extract lines are a fire issue as well as a hygiene one, so a buyer should expect the cleaning contract to produce evidence, not just clean metal. Ask for dated sheets naming the surfaces cleaned, the method and mode used, who did the work, and who signed it off. Keep those with interceptor emptying records so that a fire risk assessor or an environmental health officer can be shown both in one folder.
9. What to send when you ask for a configuration
Send the drainage drawing, the interceptor location and service history, photographs of the worst deposit on your canopy and duct, a list of cooking equipment with power or fuel type, and the hours you can realistically give the crew. That is enough for a manufacturer to propose a configuration instead of a catalogue page.
Shenzhen PowerDe Automation Precision Equipment publishes parameters for each machine in its Cleaning Equipment Series and accepts [customized steam cleaning equipment](https://www.powerde.net/diaocha/) specified against your kitchen layout and duty cycle, with [product development and hardware testing services](https://www.powerde.net/gongchengshi/) behind the equipment work. Use the [contact page](https://www.powerde.net/contact/) to send those documents and ask for a method, a litres-per-task figure and a return-to-service estimate for your own deposit, then compare that against your drainage before you buy.
