Dry steam is the mode most buyers of commercial steam cleaning equipment actually want: high-temperature vapour with very little free water, so that an engine compartment, an electrical cabinet or a kitchen wall can be cleaned without soaking the surface underneath. A machine that arrives blowing hot water instead of dry steam will fail the job it was bought for. An acceptance check is how you confirm, before the invoice is closed, that the dry-steam mode performs the way the datasheet says it does.
The check below applies to fixed, hand-pushed and driving-style machines that offer a dry/wet steam selector. Where a specific figure is mentioned, it is taken from the published datasheet of the PowerDe HW02 steam cleaner and is used as an example of the kind of value you should be comparing against.
What an acceptance check is, and when to run it
An acceptance check is a short, written verification that the delivered equipment matches the order and works as specified. Run it on the day of delivery or installation, and repeat the relevant parts after a repair, a boiler replacement, or a long period in storage. Both parties should agree on the checklist before the machine ships, so that a disagreement later is a matter of measurement rather than memory.
Do not begin with the steam. Confirm the supply conditions first, because most poor dry-steam performance at commissioning comes from the installation, not the machine:
- The nameplate model, voltage and power rating match the purchase order and the datasheet. The HW02, for example, is a 220 V machine with 6 kW of heating power.
- The supply cable, plug and socket are undamaged and correctly rated; the outlet is on a working protective earth.
- The water inlet matches the specified connection — the HW02 is designed for a tap-water inlet — and the feed pressure is stable.
- The room is ventilated and the floor has drainage, so condensate from the test has somewhere to go.
Check 1: steam temperature and pressure at the generator
Let the machine heat up until the control stops calling for heat, then read the temperature and pressure indicators. The HW02 datasheet lists a steam temperature of 160° and a vapour pressure of 0.8 MPa; your machine should reach the figures on its own datasheet, not someone else's. Record what you actually see, with the time taken to reach it. A machine that cannot reach its rated pressure, or reaches it only after an unreasonably long heat-up, is not ready for acceptance even if the rest of the unit looks perfect.
Check 2: dry-steam quality at the nozzle
Generator readings alone do not tell you whether the steam leaving the gun is dry. Carryover — liquid water travelling with the vapour — is created inside the boiler and made worse by hose length, poor insulation and a wrong nozzle. Test it in the simplest possible way:
- Hold a clean, dry cotton cloth about a hand's width from the nozzle for a few seconds. Proper dry steam feels hot and diffuse; the cloth should barely dampen.
- Watch the plume. Dry steam disperses as a thin vapour. A jet that sprays visible droplets and soaks the cloth immediately is delivering wet steam, whatever the gauge says.
- Repeat the test with the machine at a normal working level, not an empty or an overfilled tank, and with the lance and nozzle you intend to use in service.
If the steam is wet, note it as a deviation. The cause is usually a setting, a blocked or wrong nozzle, or a boiler that needs adjustment — all of which are far easier to resolve while the machine is still on the delivery note.
Check 3: mode switching between dry and wet steam
Switch between dry and wet steam several times, in both directions. The change should follow the control setting within a predictable time, without stopping the machine or requiring a restart, and the machine should return to dry steam reliably. If the mode selector is fitted, confirm that it holds its position and that the machine does not drift back to the other mode on its own. Where a vacuum or disinfection function is part of the same unit, run it separately and confirm it works independently of the steam mode.
Check 4: safety protections actually trip
Commercial machines are expected to list leakage, short-circuit, high-temperature, high-voltage and water-shortage protection. Do not accept the list on paper — test what can be tested. Trigger the water-shortage cut-out by isolating the supply and watch the machine stop and alarm as the manual describes. Confirm that it restarts correctly once the fault is cleared. Check that the housing stays touchable during a long heating cycle and that insulation and guards are in place. A protection that never trips is a protection you cannot rely on.
Check 5: water supply, tank and drainage
Fill the tank and let the machine stand. Inspect the inlet connection, the level control, the tank seams, every fitting and the drain for leaks, hot and cold. Confirm the tank material against the specification — the HW02 is listed with an 80 L SUS304 tank — and check that the level control stops filling at the correct point and that the pump primes normally. Run the drain and make sure the tank empties without pooling.
Check 6: electrical safety
Verify that the earth connection is sound, that cables and strain reliefs are undamaged, and that the supply protection device is correctly rated for the machine's current. A residual-current device should trip when its test button is pressed. These checks take minutes and are the ones most often skipped on a busy installation day.
Check 7: accessories and documentation
Go through the packing list item by item: lances, nozzles, hoses, brush attachments, seals and spare parts should all be present and should fit without force. A missing nozzle is a missing cleaning function. Collect the manual, wiring diagram, warranty terms and any certificates that came with the order, and confirm that the manual covers the dry-steam mode, the safety protections and the routine maintenance you will have to perform.
Check 8: a practical test on your own surface
The final check is the one only you can do. Clean a surface you deal with every day — a greasy engine compartment, an exterior panel, a tiled kitchen wall — and judge the result honestly. Does the steam loosen the soil without detergent? How much water runs off the surface? How long does the machine run before it needs a refill or a cooldown? If the machine cannot handle your worst realistic job at the pace you need, the specification does not match your operation, and that is worth knowing before you sign.
Record the result, and what to do if it fails
Write every check into a signed acceptance record: the item, the measured value, and pass or fail, together with the serial number, the date and the name of the person testing. List deviations separately, with the agreed remedy and a date for re-checking. That record becomes your reference for warranty claims and for future inspections, and it is the baseline against which the next check will be compared.
If the machine fails a check, do not put it into service. Record the symptom, photograph it where possible, and contact the supplier with the measured values rather than a general complaint that it does not work. Most faults found at acceptance turn out to be an incorrect supply, a blocked inlet or a misread gauge, and are resolved on the day. A genuine defect is far easier to settle while the machine is still new and the packaging is still on site.
A useful habit is to add the model, serial number, supply voltage and water pressure to the top of each line of the checklist. The record then still makes sense years later, after the machine has been moved, the staff have changed, or the unit has been replaced under warranty.
