What drift is, and what it is not
Overspray is the part of the jet that does not reach the patch you are aiming at. It comes from holding the nozzle too far back, from a wide fan set for flushing a flat roof panel now being used on a narrow pillar, and from sweeping the wand faster than the surface can accept it. It is not the same thing as run-off, which is water that reached the panel and then ran down. Run-off is expected and can be routed. Drift is wasted work: it uses water, it lengthens the job, and it carries oil and road film onto surfaces nobody intended to wet.
On a van, drift matters more than on a car because there is more vertical area and more hardware mounted to it. A panel van has flat sides that take a wide fan, but between them sit mirrors, door handles, hinges, a step, wheel arches, mud flaps, badges, printed decals and, on refrigerated bodies, external joints and the cooling unit at the front face.
Start by writing down what must not get wet
Before anyone holds a lance, agree the exclusion list for the body types in the yard and keep it on the job card. A list without a named alternative for each line leaves an unplanned gap in the wash, and the vehicle leaves the bay with a dirty area nobody decided about. The list normally covers:
- Headlamps, tail lamps and their housings, camera and sensor mounts, and any exposed connector or wiring run.
- Decals, printed fleet markings and vinyl graphics, and the edges where they lift.
- Door rubbers, sliding-door tracks, latches, hinges and the cab step.
- Brake assemblies, wheel bearings and any area where a friction surface or bearing end is exposed.
- Refrigeration units, coolant lines and the condenser face on temperature-controlled bodies.
Beside each line, write what is used instead: a damp cloth, a brush, a dry wipe, or "not cleaned in this cycle". Staff then have a decision they can follow instead of a prohibition they have to improvise around.
The sequence, not the pressure, is what limits drift
A fixed route decided in advance keeps the nozzle aimed at work rather than at guesswork. A route that crews can hold in their heads runs the same way every time: roof edge, then one full side from front to rear, then the rear doors, then the opposite side, then the lower band and arches last so the clean panels are not re-soiled on the way out. Working top to bottom means water already carrying soil cannot fall onto a face that has just been finished.
Within that route, three handling habits do most of the work:
- Trigger discipline: the jet off while the operator is repositioning, walking, or reaching around a corner. Drift created between passes is invisible on the machine and obvious on the vehicle.
- A short stand-off, kept constant. As the arm tires, stand-off creeps outward and the fan widens, which is why the last third of a long side panel is usually messier than the first.
- Soil collected, not chased. Loosened grime should be gathered toward a drain line, not pushed across an exclusion the next operator has to avoid.
Room and layout cause drift that training alone will not fix
Before blaming technique, watch a full wash and group what you see. Drift caused by aim, drift caused by sequence, drift caused by the room and drift caused by handling need different corrections, and only two of them are trained away.
In the room column sit the things a yard has to solve: a van parked hard against a fence or another vehicle leaves no working space at the rear corner, so the operator sprays from an angle across an already-clean face. A hard, level standing with a clear perimeter, room to walk the full length, and a defined drain route give the operator a position where the correct angle is also the comfortable one. Where water is supplied, ask what runs while the crew works and how far the hose has to be dragged, because a hose that pulls is a wand that swings.
Run-off belongs in the plan as a task with a route, not as an accident. Decide where the water goes before the first pass, keep the path clear of pedestrian routes, and treat the collected water as a waste stream to be handled under whatever rules the site operates under.
Match the machine to the vehicle, not to the catalogue
A van is tall and long, which is where a wash bay runs out of reach. Decide whether the work is done from a fixed position with the vehicle moved past it, or by an operator following the body, then choose equipment that suits that answer rather than the largest listing. The mobile steam cleaning machine class on PowerDe's cleaning pages is positioned around tight indoor garage bays and cramped outdoor parking, which is close to how a yard washes vans between deliveries. The fixed steam cleaning machine class suits a marked bay where vehicles come to the equipment and drainage already exists.
Whichever class is quoted, ask for the specification of that exact unit in writing, and do not transfer figures between pages, variants or previously delivered machines. The site's product pages publish different fields for different models, and a rating printed on one card says nothing about another. Where a vehicle fleet needs a duty the listed scenarios do not describe, that is a question for the supplier rather than an assumption to build into a purchase order; PowerDe lists customized steam cleaning equipment as something it works through with buyers.
Write the finish as something a person can check
"Clean the van" cannot be graded, so it cannot control drift. Replace it with conditions: no film left along the lower band and arches; no wetting recorded at any exclusion line; soil not left standing at a door sill or in a track; glass and mirrors clear after the pass, not re-soiled by it. Then check the vehicle rather than the effort, and let the person doing the checking be someone other than the one holding the lance.
Prove the change on one van before writing it into the routine
Pick one body type and run the new route and the exclusion list on it, with photographs of the same panels before and after, and with drift recorded as a count of the places water landed where it should not have. Decide the stop condition in advance: if drift at the exclusion lines does not fall on that first vehicle, the answer is the route, the stand-off or the room, not a stronger jet.
Send the same four questions to every supplier you are comparing, unchanged, so the answers can be read side by side: which of the exclusion items on our list can this unit be used against, and which cannot; what is the specification of the exact unit quoted, as a written row per field; what is reached at the top edge of a panel van without a ladder or a second person; and what happens to run-off on a yard without a drainage channel at the wash position.
Once one body type holds the standard, put it on one page per vehicle family, name the owner, and set a review date. Drift comes back quietly when a route is shortened to get a van out for its next round, and the page is what makes that visible.
