You’re in the outback, among the back roads beating up great clouds of dust on the way to hidden tourism gems.
The trouble is that when you set up camp, the enjoyment of the adventure can quickly fade like a whisper on the breeze when a thick layer of super-fine dust, known out this way as bulldust, swamps your van and ends up resting on every interior surface.
To stop your van interior looking for the entire world like a doughnut shop’s cinnamon sugar dredge or your cat’s kitty litter, you might consider a little dust prevention. We heard positive pressure or scupper vents can make it happen. But do they work?
Let’s open a window to the world of scupper vents and put a hole in the myths.
GETTING SCUPPERED
The idea is that if you place a small vent on the roof of your caravan or motorhome and leave it open as you drive an outback track, the variation in pressure between the inside and the outside of your rig will keep the interior dust-free. Quite simply, you scupper the chance for dust to seep in as you rattle along.
Leap Australia’s Engineering Solutions Manager Joel Thakker is somewhat of an aerodynamics expert. Although he doesn’t completely subscribe to the pressure argument, he says that it’s difficult to know if a scupper vent will keep out the dust.
Thakker reckons the trick is if you start in a clean environment then the air that flows into the caravan will be clean and, as you drive, you gather enough air inside the van that eventually it has nowhere to go and that still, stagnant air will act as a wall preventing more air coming in. At that point, if the exterior is dusty, the dust won’t get in.
“At the speeds that most caravans travel, it is hard to push more air into an already ‘full’ caravan. So, if you started off in a clean environment and then went into a dusty environment, I can see the vent doing its job,” Thakker explains.
The trouble is when you start off in a dusty camp or on a dusty track and continue driving in that dusty environment, “then you are just filling up with dust and then after a while, when the caravan’s full of dusty stagnant air, you won’t let in any clean air.”
Thakker also says that scupper vents might also be less effective if you accidentally leave a window open or there’s another vent open as you travel. In this case, scupper vents aren’t going to do much for you because there will be a constant stream of air going through the caravan interior.
You can see the effect for yourself. Open the front window of a car and you won’t feel much breeze. Open two windows and you get cross ventilation as fresh air is constantly flowing. In a caravan, an open scupper plus another opening elsewhere in the van might just help dusty airflow through the van, depositing dust as it goes.
However, Thakker says the effect of a second open vent or window while travelling depends on where the other vent is in relation to the scupper. A door vent, some distance and not in a straight line from the scupper might not reduce the efficiency of the scupper.
It seems that scupper vents are likely to help but the aerodynamics of the caravan-tow vehicle combo and the existence and placement of other open vents or windows might scotch their efficiency.
In fact, Thakker reckons that unless you start your day’s trek in a clean environment, say on the blacktop, there’s little a scupper can do.
On the upside, as they’re usually under $100 plus fitting, they’re a relatively inexpensive strategy albeit not necessarily the end of your dusty overture.
TOWARDS THE FUTURE
The word is going around that giant caravan equipment supplier Dometic is looking at introducing to the caravanning world a new dust prevention device that might go a long way towards solving the problem of dust ingress in caravans and motorhomes. Time will tell.
Meanwhile, there are other technologies available like filtration units. LSM Technologies offers one such unit called a RESPA Cabin Pressuriser Filtration Unit that LSM’s Peter Woodford says is “great and we have many caravanners using this and very successfully to eliminate dust in their units – especially on dirt roads.”
The technology spins the air forcing the particles into a filter leaving clean air rather than the stale dirty air inside your caravan or motorhome. At around $1500 for a full kit, it’s an interesting but more expensive alternative to a scupper vent.
The full feature appeared in Caravan World #573. Subscribe today for the latest caravan reviews and news every month!