Vacuum sweepers work exactly how their name describes, by vacuuming debris off the ground and into a hopper.
Other air sweepers also use a vacuum combined with a continuous blast of air creating a closed-loop or Regenerative Air System. In both systems increasing the amount of air flow can be attributed to a number of factors:
Increasing the Auxiliary Engine RPMs
Air sweepers get their suction from a large blower fan that is turned by an auxiliary engine or PTO.
As the speed of the fan increases (and the amount of air that the fan is moving) so does the amount of suction generated from the fan. In many sweepers, where the fan is directly driven from the auxiliary engine, increasing the engine speed (RPMs) will increase the amount of suction.
However, you can have too much of a good thing. Moving the air faster changes how well the debris drops out of the air flow once it enters the hopper. Move it too fast and the internal screens get blocked and efficiency drops quickly. Increasing RPMs beyond optimum levels leads to diminishing returns and quickly becomes counter productive.
Sweeper manufactures design their sweepers to operate within an RPM range that can be optimized by a trained operator to maximize debris pick-up.
Decrease Sweeping Speed
Decreasing the speed that the sweeper is moving gives the vacuum more time to move the debris. So while the sweeper isn’t sucking any harder, the suction that it does have is allowed to work longer on the surface area. For an advanced write up visit StreetSweeper.com
Moving slower means that the amount of cleaning ability per square foot increases without increasing the suction itself.
Clear Obstructions in Vacuum Tubes
Some of the debris that are swept up will be mud or clay and it will want to stick to everything it touches, including the suction tube or up-tube and hopper of the sweeper.
As more and more mud sticks to the inside of the up-tube, the tube will narrow and get choked up, restricting airflow. Reduced airflow means reduced suction.
When you’re sweeping up sticky debris, check your up-tube every couple of hours to make sure it is clear and unrestricted. This is especially important when you’re doing construction sweeping since you may be picking up a lot more sticky mud than on a normal parking lot, city, or HOA route.
Keeping the air flow areas inside the sweeper clean is the number one thing to maintain a sweepers cleaning ability. This is so important that air sweepers must have a through wash out after every shift and sometimes even during shifts.
Unlike broom sweepers, this washout can easily add an hour to the operator’s day. It also creates a fair amount of water that must be recycled or disposed of properly.
Seal any Air Leaks
It’s important that the vacuum system of the sweeper is as air tight as possible. If there is air leaking into the system besides where it should be, at the pick-up head, suction will suffer. Some common places to look for air leaks are:
- Around the inspection doors
- Small holes in the hopper from rust or wear
- A tear or hole in the up-tube or down-tube
- Cracks on the pick-up head
When the truck is running, see if you can hear or feel where air may be entering or leaving the vacuum system. Escaping air has a high pitch sound that is easy to recognize.
Empty your Hopper
When your sweeper it too full of debris, airflow dynamics are changed and cleaning effectiveness will decrease. Don’t allow your sweeper to get too full so that air can’t circulate properly through the hopper.
Keeping your sweeper at peak performance can be as simple as dumping more often.
Experiment with your Leaf Bleeder
Regenerative air vacuum sweepers are a closed loop system. There is a pressure side and a suction side. The two sides will always be in balance. These sweepers have a valve that allows them to bleed air off the pressure side. While it may seem counter intuitive, reducing the amount of air in the pressure side of the equation allows more air flow from under the front flaps, changing the suction side of the equation.
Debris with different densities will react differently to the amount of suction. Some debris, like leaves, actually pick up better with lots of air bled off.
While the intentional changes in the “balance” of air flow are important for operators to understand, unintentional changes caused by even a small air leak will reduce the sweepers ability to control dust. Moving debris at over 200 mph without creating fugitive dust is as much art as it is science.
Repair Worn out Components
Over time components can get worn out. If components like the blower fan get worn out it can’t move as much air and you’ll lose suction. Keeping your vacuum sweeper well maintained will help it sweep better and last longer.
This brief article just scratches the surface. In fact, some sweeper manufactures such as Tymco, have multiple-day schools at the factory covering the above and other sweeper specific topics in detail.
At Bill’s Sweeping we do our best to practice what we preach. These tips are just some of the basics we go over when training new operators or maintaining equipment.
If you’re interested in hiring a vacuum sweeper for your next project, give us a call at (714) 637-3180 or download our rates for a vacuum sweeper.