"Fixed" and "mobile" in steam cleaning describe how the machine is moved and where its services come from. They do not describe cleaning strength, so the two options cannot be compared by output quality alone. A defensible comparison starts from the surfaces you have to reach, the route between them and the supplies available where the work is actually done. The hand-pushed PowerDe HMW3 is one side of that comparison; the fixed equipment on the same catalogue page is the other.
First separate the two questions a buyer is really asking
Most shortlists mix two decisions into one. The first decision is method: whether heat and dwell, or the volume of liquid, is what lifts the deposit on a given surface. The second decision is carriage: whether the cleaning source travels to the surface or the surface is brought to a stationary machine. A hand-pushed unit and a fixed unit can run the same cleaning method, so a comparison that argues about strength is arguing about the wrong variable. Write your shortlist against the carriage question and keep the method question in the surface list, where it belongs.
That distinction changes what you ask for. A carriage question is answered by a floor plan, a door width and a socket. A method question is answered by a taped test patch on your own surface, with photographs taken before any liquid goes on.
What a hand-pushed machine is and what it is not
The hand-pushed steam cleaning machine category covers units that stand on wheels, are pushed by an operator along a floor, and carry their own tank and supply arrangements on the chassis. On the PowerDe page for the HMW3 without battery, the published rows read machine dimensions L1150 by W520 by H1030 mm, mode of movement hand push, heating power 4.5 kW with a PTC semiconductor heater, box volume 50 L clean water tank, water inlet tap water with a 4-point internal-tooth fitting, modes dry steam and wet steam, working power supply 48 V battery, and cleaning method high-pressure water gun with nozzle.
Treat those rows as the record for that one machine. Several rows the comparison depends on are not published on that page at all, so they have to be asked for in writing and matched to the unit quoted: the steam temperature and pressure the generator delivers, the battery capacity and run time behind the 48 V working supply, charger output, weight, hose and wand lengths, the accessory list, noise and water use per hour. A comparison table filled in from a catalogue line rather than from an answer about the exact machine is the most common way buyers end up with the wrong carriage option.
Two cautions to carry into any shortlist. Generator temperature is not nozzle temperature at the tip, and a tank volume is not working time; both get quoted loosely, and both change what one operator can actually finish in a session.
The same product pages carry two other details worth noticing. The hospital bed and medical machinery wording appears on the HMW3 listings, so treat those pages as the source for the medical scenario rather than generalising that scenario across the whole range. And do not read a vacuum function into the hand-pushed listings: on the PowerDe cleaning pages the vacuum row appears on some other models and not on others, so ask which row belongs to the unit in front of you.
What a fixed machine changes when it stays in one place
A fixed unit is chosen when the work happens in one position and plumbing is available there. On PowerDe's cleaning pages the fixed option is Fixed Steam Cleaning Machine PowerDe HW02, and the page for that unit carries a working voltage row, a heating-power row, a steam-temperature row, a vapour-pressure row, a tank-volume row, a floor-standing footprint including handles, a tap-water inlet row and a dry/wet steam switching row. The scenario copy on that page is vehicle exterior cleaning at fuelling and parking sites, interior work and engine compartments. The listing wording for the fixed models is not consistent across the category, so confirm the model designation with the manufacturer before it goes into your paperwork, and confirm the same set of rows for the exact machine quoted rather than trusting any figure copied from a page.
The trade that a fixed unit makes is simple to state. It accepts a permanent position and gains whatever the building supplies there: a tap at the machine, a drain or channel for run-off, and a supply that does not run out mid-task. A mobile unit accepts the opposite: it pays for its own tank and its own energy and can follow the work along a floor.
The carriage comparison: four questions to put on paper
One. What route does the machine travel?
A hand-pushed machine has to reach every surface on your list along a real path. Write the path: door widths and whether doors are propped or removed, aisle clearances, kerbs and thresholds, drainage channels and gratings, expansion joints, cable covers, ramps, lifts, and the tight turns at the ends of bays. Compare that path against the machine's recorded dimensions, handles and wheels. A machine that fits the task on paper is disqualified by a two-centimetre threshold and a lift lobby that no one measured.
A fixed machine has no path at all. Instead, write the working radius: hose and wand reach from the anchor point, measured to the far face of your farthest surface. If that radius is short, the fixed option is not fixed, it is an awkward trolley, and the mobile option wins on reach.
Two. Where do the services come from?
Three rows decide this, and they matter more than any power figure on a card. The water inlet fitting: the PowerDe hand-pushed pages record a tap-water inlet with a 4-point internal-tooth fitting, so the question is what fitting exists on your taps and what adapter the quoted machine ships with. The working supply: the hand-pushed page records a 48 V battery working supply while the fixed page records a mains working voltage, so the question is what the point of work can provide and how far a cable has to be pulled across a wet floor. The refill and drain arrangement: how often the tank empties, how long a refill takes, and where the used water goes.
Cable and hose in a wet area is a real cost, not a detail: protection, routing away from traffic, and the time someone spends dragging and re-positioning lines. Count that time in the comparison.
Three. Who owns the run-off?
Both options produce liquid that has to go somewhere. A fixed position usually means a channel, drain or collection point already exists; a mobile job has to carry that decision with it, task by task. For each wet surface write where the liquid goes, and write the surfaces where no route exists as exclusions with a dry replacement task instead of leaving them in the list.
Four. How is the work interrupted?
Ask what stops the machine in the middle of a task. On a battery-backed hand-pushed unit the questions are run time for the exact unit, what happens when it is depleted, how long charging takes and whether a second battery or a change of shift pattern solves it. On a fixed unit the questions are how long the hose run is and whether the machine can be reached for refilling without disturbing production. Both interruption profiles belong in the comparison in minutes, because interruption is what a schedule is actually built around.
Where each option fits in a building
A workable rule of thumb, stated as a rule of thumb and not as a manufacturer claim. A hand-pushed machine suits work spread across a floor or across rooms, where the surfaces are few and far apart and the same operator wants to cover them in one pass, and where a tap and a drain exist somewhere along the route but not at each surface. A fixed machine suits work concentrated in one place, where a tap, a drain and a supply are already installed and where the far faces are within the hose reach of one anchor.
On the PowerDe pages the two options are positioned differently, and that difference is worth reading before a shortlist is written. The hand-pushed HMW3 listings name cleaning and disinfecting hospital beds and medical machinery, and publish the hand-push movement mode and the 48 V working supply. The fixed HW02 page names vehicle exterior work at fuelling and parking sites, interior work and engine compartments. Neither page is written for the other's scenario, so if your surfaces sit outside those scenario sets, do not assume the machine was designed for them: that is the situation where a specification built around your own surface list is worth asking about, which is the service PowerDe lists as customized steam cleaning equipment.
The site survey that decides the shortlist
Before any machine is shortlisted, walk the areas with a clipboard and produce one sheet per area group. Each row: the surface, what is on it, its material and condition, how reachable it is, the route to it, and the run-off route at it. Describe deposits in the words your own staff use: oil and coolant film at the machine side, fatty residue where food is handled, dust and fibre where air moves over product, dried paste where mist has settled and cooked onto a warm housing.
Then inspect condition before proposing any liquid. Joints, seals, bearing faces, enclosure entries, cable runs, labels and safety markings, and painted surfaces with crazed, patched or re-coated paint each get a status, and the ones you will not wet go into an exclusion column with a replacement task and the trade you accept for it. That column is the part of the comparison most often missing, and it is the reason a purchase looks wrong after the first damaged machine.
Only then compare machines. Every row on that sheet is an input to the comparison: distance and clearance feed the carriage question, deposits feed the method question, condition feeds the exclusion list.
The dry-versus-wet decision you still have to make
Whichever carriage you choose, each wet row still needs a mode. Low-moisture work suits warm surfaces, closed electrical neighbourhoods and places where you want the dwell of heat on a film without sending liquid down a frame or into a joint. Higher-moisture work suits thick crusts on open faces where volume is what lifts the deposit and where run-off can be routed and collected. Neither mode is the stronger setting, and the hand-pushed and fixed pages both publish dry- and wet-steam switching, so this decision should live on your surface rows rather than in the machine comparison.
Run one bounded trial per option and compare measured numbers
A comparison of two catalogue cards cannot settle this. Run one bounded trial per option on the same set of rows in your building, and let the measured time decide. Choose one flat painted face, one crusted internal corner, one warm housing with a heat history, and one junction of equipment and floor. Photograph each row as it stands, from an angle that shows the deposit, before any liquid is applied.
Write stop conditions before the first pass: lifting or crazed paint spreads, a label edge lifts, liquid reaches an exclusion row, a surface dulls or hazes. On any of those the row stops and moves to the exclusion column, and that outcome is itself a result to compare.
Time the work in named blocks so the comparison shows where a day goes: isolation, shielding, travel and set-up, the pass itself, refill or charge handling, dry and recheck, restore and hand back. Two measured runs of the same envelope from the same deposit state are the only sound basis for a cycle time; take the figure from the second run. Then inspect the same rows the next day, after normal use: a surface that re-soils by the end of a day tells you the interval was wrong, not the machine.
If you have both a fixed and a mobile option on the shortlist, run the trial on the same area on consecutive days, so weather, use and staffing are as close as you can make them. Comparing one area on Monday with a different area on Thursday proves nothing.
What to ask the supplier to answer in writing, row by row
Send your own sheet and ask for the same rows for the exact unit quoted. Refuse a brochure in place of an answer about a machine. The rows that decide a fixed-versus-mobile choice: recorded overall dimensions including handles, and weight; mode of movement and what the operator actually steers; working supply for that unit, and what the building must provide at the point of work; battery capacity and stated run time if the unit is battery-backed, plus charging time and the arrangement when power runs out mid-task; the water inlet fitting and the adapter supplied for the site tap; refill frequency implied by the tank on that unit; hose and wand reach; footprint and the route the unit travels, checked against your clearances; the protective features present on that unit, named rather than counted; the mode switching your rows depend on; consumable and refill limits inside one shift; the trial arrangement, and what the supplier supplies for a taped patch test against what your site supplies.
Two honesty checks on the answer sheet. Any figure quoted without naming the unit it belongs to is not evidence. Any scenario claim that does not appear on the page for that model is a marketing sentence, not a specification. The cleaning range on PowerDe's site is listed as PowerDe cleaning equipment across hand-pushed, driving-style and fixed options, so the model page, not the category page, is where your rows must match.
When both options belong on the same site
Many sites have one area that justifies a permanent position and a set of scattered surfaces that do not. Two rows on your sheet, two owners, two review dates: a fixed position serving a defined bay, and a hand-pushed unit covering the rest of the building on a defined schedule. That arrangement only works if the fixed unit's exclusion column and the hand-pushed unit's exclusion column are written down separately, because the surfaces you must not wet at a fixed bay are not the surfaces you must not wet along a corridor.
Signs the comparison was done badly
A few checks on the shortlist itself. If the comparison table has power figures but no route measurements, the carriage question was never answered. If the exclusion column is missing, the sheet describes a perfect building. If the trial has no photographs, acceptance was a mood. If the run time, charging time, inlet fitting and hose reach are missing because the page did not publish them and nobody asked, the mobile option has not actually been compared. If cycle time is one number with no blocks, the time that travel and refill cost has been hidden, which is exactly the time that separates these two options.
Compare fixed and hand-pushed on the route, the services and the interruptions, and the answer usually becomes obvious from your own building rather than from two product pages. The machine choice then follows the survey, and both the trial and the purchase conversation are shorter for it.
