17th International Symposium INFOTEH-JAHORINA, 21-23 March 2018 Control system for portable dry ice cleaning device Miloš D. Jovanović, Željko V. Despotović, Marko R. Tajdić Institute “Mihajlo Pupin”, University of Belgrade Belgrade, Serbia milos.jovanovic@pupin.rs, zeljko.despotovic@pupin.rs marko.tajdic@pupin.rs Slađan Milanović Institute for Medical Research, University of Belgrade Belgrade, Serbia sladjan.milanovic@imi.bg.ac.rs Abstract — In the paper will be described a control system of a dry ice cleaning system. One such cleaner can be used in various branches of industry such as: electrical, metal, wood, automotive, food, pharmaceutical, plastics, paper and cosmetics industries. It can also be used in printing, steelworks and for removing graphite from the walls by removing impurities and not damaging the substrate material. The dry ice cleaner is characterized by the appropriate speed, flow and vibrations that need to be generated. The cleaner should be robust and have a wide range of operating temperatures. There is a very necessary protection from static electricity, which is easily generated by constant vibration and friction, which can very badly affect, and even lead to the failure of the entire control system. The software of this control system is protected from external influence by WDT, Watch Dog Timer. Also, the software is written so that it can recognize improper handling by a cleaner. In case of improper handling, the software will protect the user. Keywords – Control system; Dry ice; Cleaning; Static electricity I. INTRODUCTION The main purpose of a portable dry-cleaning machine based on dry ice is to remove impurities from different surfaces. Cleaning with dry ice has special advantages compared to the classic sandblasting or high-pressure cleaning process. Dry ice strongly removes dirt, and after spraying dry ice pellets completely pass into a gaseous state, carbon dioxide (CO2) [1]. This means that there is no liquid state, but from a solid state directly pass into a gas state. In this way, the cleaner does not leave abrasives behind it, such as sand or glass granulates and there is no waste, dirty water. Also, it is very important that you do not have to disassemble the machine before cleaning, because the dry ice particles reach the smallest corners, so that the machine's standstill time is minimized. Cleaning on dry ice basis is environmentally safe and does not damage the nature for several reasons, and some of them are: there is no risk of bacteria because there are no residuals of water, carbon dioxide is not toxic and the gas is not harmful. When the impurities are not removed in this way, the material nor the surface from which the impurities are removed will be damaged. The technological process of cleaning itself can be explained in the following way. The particles of dry ice are accelerated by compressed air at a rate of over 150 m/s and due to the cold of about -79ºC impurities freeze and get cracks, and then the fraction of dry ice at their high speed can eliminate impurities. Fig. 1 illustrates the previously described process. Figure 1. The process of removing impurities The portable cleaning device can be used in various industrial branches and for various purposes, and some of them are listed below. Steel, metal industry and machinery where cleaning is done in order to maintain production machines, welding robots, conveyor belts and varnishing facilities. In the wood and electrical industry for the cleaning of woodworking machines, generators, turbines, control cabinets, etc. In the plastic and packaging industry, the dry ice drier removes silicone and rubber as well as paint, varnish and many other impurities. This device can be used in foundries, automotive, food, pharmaceuticals, cosmetics and paper industries. The cleaner has also found its application in the removal of graffiti from the walls. The dry ice cleaner is characterized by the appropriate speed, flow and vibrations to be generated. The technical requirements that the device should satisfy are robustness, wide range of operating temperature and protection against static electricity. A very high need for static electricity protection has arisen because static electricity is easily generated by constant vibration and friction, which can be very badly affected and even lead to the failure of the entire control system. Also, it was required that the software of this control system be protected from external influences. Fig. 2 shows the entire portable cleaning device. 978-1-5386-4907-7/18/$31.00 ©2018 IEEE