A flat surface cleaner is that thing that looks a little like a lawnmower that is used for cleaning driveways and other flat areas (like roofs, walkways, walls, buildings, decks, etc.)
Some contractors hesitate to invest in one of these cleaners because of the cost, only to discover after they buy one that it pays for itself in just a few jobs. These cleaners have come down in price so much over the last five years that the smaller ones are practical and affordable even for casual users. Buying the right flat surface cleaner for your needs requires some homework to maximize your cleaning power.
The swivel is the heart of any flat surface cleaner. Cheap swivels fail frequently, while quality swivels can run for years with little or no maintenance. More swivels are being made in China than ever before, with mixed reviews on their quality. At this time, none are more durable than European-made swivels. Swivels are the most expensive part on any surface cleaner, and skimping here is a waste of time and money. Swivels do all of the work under very tough conditions, spinning as fast as 1500 or even 2000 RPM while standing up to high-pressure, high-temperature water.
The hood or dome of the surface cleaner can be made of a number of materials, including fiberglass, steel, stainless, aluminum, plastic, vinyl, etc. Plastics, which are on the most budget-friendly units, can warp if left in a hot truck in August. Metal domes tend to give the longest service. Aluminum is lighter than steel. Stamped stainless can be even lighter than aluminum.
There are several design characteristics beyond the construction materials to think about. The handle must be comfortable to use and allow you to maneuver the cleaner easily. The diameter, or size, can make a huge difference. The spray bar may have 2, 3, or 4 nozzles. The equipment may have casters or a brush skirt ? or both.
Surface cleaners that float (no wheels, just a brush skirt) allow great maneuverability. Wheeled units maintain a uniform distance from the surface, but can be slightly more difficult to move into a tight area. Some wheeled units have fixed axles and are easiest to use in a front-to-back straight line approach, while floating units and those with casters can be swung from side to side without much difficulty.
The purpose of the brush skirt is to protect the operator from flying debris and to prevent the water from being thrown all over. Once in a while an over-zealous salesman might suggest that the brush skirt actually provides some scrubbing to the surface, but if it actually did that it would add significant drag to moving the surface cleaner around.
Casters can present a small problem of their own if they are allowed to run off the side of pavement. With the bar spinning at high RPM, any contact of the nozzles or the bar with the edge of the concrete can be an expensive mistake.
The pressure going into a surface cleaner is the same pressure at the tip of each nozzle on the bar. Pressure is not divided by the number of nozzles. On the other hand, the flow (GPM) of your power washer is divided by the number of nozzles on your surface cleaner.
What size of surface cleaner to buy is what confuses most buyers. Whether to buy a 30? unit or an 18? unit is a function of the volume of the power washer that will be supplying the surface cleaner. No matter what the output of your power washer is, it will clean the same area over the same period of time whether you use a 30? model or an 18? model. The difference between the two will be in how fast you move the cleaner while you are working.
To decide which size to buy, keep this in mind. We know that the output of the power washer (in gallons per minute) is divided among the number of nozzles. Our target has to be to get as close to 2 GPM per nozzle as possible for cleaning power. If we have a 4 GPM power washer and we are considering a 3-nozzle surface cleaner, then our flow at each nozzle is (4 / 3 =) 1.33 GPM. That is too low for effective cleaning. I suggest that the smallest volume of water per nozzle should be at least 1.5 GPM, and closer to 2 GPM is better.
Now that we know the number of nozzles we want, we need only determine the diameter, or ?cleaning path?. The larger the cleaning path, the slower we have to move to clean properly. The larger the cleaning path, the fewer steps we have top take. The smaller the cleaning path, the lower the relative price for the equipment. Inversely, larger equipment costs more. Your personal preference comes into play at this point.
The most scientific approach to selecting the right surface cleaner requires you to take another look at the power washer you will be using. If the GPM is under 4 GPM, then you are sending less than 2 GPM to each nozzle. The more you are under 2 GPM per nozzle, the smaller the diameter (cleaning path) I would recommend. I would suggest that a 3 GPM power washer should be connected to a 16? or 18?. A 3.5 GPM machine might best be matched to an 18? to a 21? surface cleaner. A 4 GPM power washer will easily work with a 21? or 24?. Once you get to 5.5 GPM or more, you should definitely consider a 3-arm surface cleaner.
Now to nozzle sizes. Most surface cleaners are equipped with nozzles from the factory. Those nozzles are not sized exactly for your equipment, but are a general size to fit the average buyer?s pressure washer. Using a standard nozzle chart, look up the PSI and GPM at each nozzle. If you have a 4000 PSI, 4 GPM power washer, and you are buying a 2-arm surface cleaner, then look on the nozzle chart for 4000 PSI and 2 GPM. That will tell you that you need a 2.0 nozzle orifice. The angle of the nozzle, such as 15§, is of less importance than the orifice size to most operations.
When you order a new surface cleaner, you can specify your desired nozzle size. Expect an up-charge to have them changed out for you before shipping the surface cleaner to you.
Just when you think you have seen everything, something new comes along that just makes good sense. There are surface cleaners made for cleaning roofs, which is a blessing when you look at some of these roofs with pitches like church steeples.
Another variation on styles is a surface cleaner with vacuum ports installed. These are designed to allow the user to vacuum the water while they are cleaning. This is an ideal configuration when using these tools indoors or when you have to capture all of your used water (for environmental reasons).
In the end, a good surface cleaner will speed up your job and add greatly to the uniformity of the overall cleaning. They pay for themselves reasonably quickly, and they give your company a professional image.