Productivity & lack of damage are two great reasons and below we will look at the mathematics of why it makes sense to take a few minutes to match up your spray bars for the application being removed.
For most jobs out there, you can choose a tool that will get you by or you can choose the very best tool. This is no different when operating a water blasting system. One of the first steps to get the most productivity out of any water blasting system is to choose the right spray bar for the job.
Stripe Hog SH8000 Removing Road Marking
Pavement markings, for instance, are unique in their composition, profile and strength depending on the original application process, age and thickness. Every pavement type is also unique in its qualities, whether it is concrete or asphalt. Some of the pavement marking variables include:
With so many variables in the marking and pavement qualities, one size does not fit all and the proper choice of spray bar becomes very important to production rates and to the quality of the removal.
For instance, let’s look at an example where we are using two blasting heads and each spray bar is delivering water through it at 6 gallons per minute or gpm (22.7 liters per minute or lpm). A spray bar that has 15 nozzles delivers .4 gpm (1.5 lpm) per nozzle and a spray bar with 30 nozzles delivers .2 gpm (.75 lpm) per nozzle. More water means more impact – less water means less impact. A spray bar with 15 nozzles is more aggressive than the spray bar with 30 nozzles. The spray bar with 15 nozzles is capable of penetrating harder materials very quickly, but it takes more revolutions per minute (rpms) to cover the area than a spray bar with 30 nozzles. Think about coloring a full page of paper with 5 crayons in your hand versus with 10 crayons in your hand. Which one would fill in the page faster?
Marking materials are designed to be very durable and tend to break apart in large chunks when removed. The larger jets penetrate the material quickly, breaking it apart and removing it from the pavement surface. Runway rubber is not durable so it comes off in very small, fine pieces like dust, which means that it takes more nozzles to cover the area quickly. The spray bar with 30 nozzles is capable of taking off the markings but it will take approximately twice as long to do it. The spray bar with 15 nozzles removes runway rubber build-up very easily, but it may penetrate further into the surface. Either spray bar can be used for either job but they work more efficiently when paired with the appropriate task.
Our experience has taught us that the 15 jet spray bar is almost twice as fast at removing paint markings as the 30 jet spray bar and the 30 jet spray bar is almost twice as fast at removing runway rubber than the 15 jet spray bar.
The below video shows the time frame to exchange rubber removal spray bars for marking removal bars on a Stripe Hog Waterblasting System. While you certainly could have performed rubber removal with the pavement marking removal bars, there are clear advantages to taking 3 ½ minutes to change them, so let’s discuss them below.
As seen in the above video, it is very quick and easy to exchange the spray bars on the Stripe Hog and just to recap, here are the reasons why we want to choose the right configuration:
- Spray bars are changed in order to match the qualities of the markings and the substrate (pavement) conditions they reside on.
- Spray bar widths are matched to the marking width to ensure that all of the energy is focused on the material to be removed, rather than on the outlying surface.
- The aggressiveness of the selected spray bar is also matched to the durability of the marking or pavement surface.
This assessment and exchange of spray bars not only increases the efficiency of the process by not wasting water, but it also reduces the risk of damaging the surface outside of the marking.
The 3 ½ minutes used to match the spray bar tool to the task are not wasted minutes in terms of efficiency, production or the bottom line. This short amount of time is an investment that pays dividends in increased productivity and reduced impact to the pavement surface, thereby producing a better quality job.
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This guide was established as a beginning point in bringing objectivity to the industry. Paint trucks don’t paint crooked lines any more than water blasting trucks damage pavement surfaces. It is our hope that the industry will come together to establish standards that will protect the rightful reputation water blasting has earned as the leading method of removing pavement markings with minimal surface impact.