Summary: Many businesses use large amounts of water to clean heavy machinery such as automobiles, buses and various other vehicles. Producing an effective and safe wash is integral to proper appearance and environmental concerns. Deionization, though not new to the industry, represents one process for virtual spot-free performance.
Commercial vehicle washing techniques around the world vary from the low-tech—park your car in the stream and pay someone to splash water on it—to the very sophisticated, automatic, assembly line style systems. All of these methods are effective but most utilize large volumes of water and rely on mechanical drying methods to remove residual rinse water. The removal of all water is a necessity in most parts of the world to avoid calcium carbonate spotting. In addition, a high percentage of automobiles are washed in streets and driveways—releasing large quantities of soap and water—adding significantly to the problems associated with urban runoff.
Soap-free, low-flow, high-pressure deionized water systems—for removal of all ionized minerals and salts by a two-phase ion exchange process—have made it possible to reduce water consumption by 90 percent while allowing spot-free evaporation of residual wash water. These systems, like the ones used by the professional car care industry, are extremely fast and effective. Deionized water, when used in this application, must have a total dissolved solids (TDS) level of less than 15 parts per million (ppm). Water meeting this quality criteria can be produced through distillation, reverse osmosis (RO) or through use of chemical beds. Inherent simplicity and reliability of chemical bed ion exchange method makes it preferable for a self-service, unattended kiosk.
User interface is similar to a self-service fuel dispenser. A credit card is inserted and removed from the card reader. High-pressure, deionized water is dispensed and billing takes place when the wand trigger is depressed. Most cleaning can be accomplished simply by spraying. Waterborne road dirt, when allowed to dry on the vehicle, must be wiped after re-wetting. Oily deposits require soap as an emulsifier. At the wash’s conclusion, the wand is placed in a holder and the vehicle allowed to air dry.
Soap-free, high-pressure cleaning systems utilizing deionized water have a number of benefits in addition to the obvious one of convenience. These include reduction in water consumption and associated wastewater. The comparison in Figure 1 illustrates average water use associated with various car-washing methods. It’s valid for other vehicle-washing applications as well.
How it works
Components of a high-pressure, deionized water wash system consist of a high-pressure pump, pressure regulator, valves, manifolds, a backflow preventer, deionizing beds and a control system. Control system functions include:
- Credit card reading and interpretation,
- Operation of valves and motor contactors,
- Interpretation of data generated by digital and analog water pressure, TDS, pH and flow sensors,
- Display of messages on an LCD user display,
- Storage of transaction and water quality data,
- Encryption of credit card user account numbers,
- Routine communication of data through the Internet,
- Non-routine communication of events that result in a unit shutdown, and
- Support of remote control sessions enabling diagnosis or support to field personnel engaged in troubleshooting and repairs.
Control system design
The control system’s overall design objective is to allow an industrial process to be adapted for consumer use. This means design considerations of deionizing beds, such as high start-up TDS, potential acid tail-off and high TDS at bed depletion, must be eliminated without requiring an operator interface. Warning methods—lights or audible alarms—can’t be relied on as safeguards. High TDS at system start-up is a feature of all deionized bed systems. Use of a mixed bed resin instead of a separate anion and cation beds substantially reduces water flow before reaching an acceptably low TDS level. Problems associated with TDS increase between sessions are reduced by recirculating water through the mixed bed at system start-up and at any time the wand trigger isn’t depressed.
Supervisory control and data acquisition (SCADA) systems have become commonplace in municipal drinking water and wastewater systems. This technology applied to this particular point-of-entry (POE) application results in creation of a practical freestanding credit card operated kiosk. Approaches, such as programmable logic controllers (PLCs) and single-board computers were considered, but a PC-based control system was chosen based on the its inherent advantage in memory, communication capability and use of standard software and hardware. The control system utilizes a Microsoft Windows 98 operating system written in Visual Basic.
Data, like the control panel shown in Figure 2, can be viewed by maintenance personnel or through various remote control programs. Communication software allows for routine (daily) and non-routine (out of limit conditions) communication between units and maintenance personnel. Internet access is by hardwire or cellular wireless data transmission. Typical communication includes performance logs and billing data.
Figures 3 and 4 are actual data displays utilizing Microsoft Access software for easy interpretation, trend analysis, billing and other functions.
Remote monitoring, control
Monitoring and control are accomplished through use of a wireless
data link and the Internet on a real-time basis. Figure 5 shows a typical remote control session with a unit in actual operation. Maintenance personnel can access files and control functions located at the unit or a remote site. Changes to these files and controls can be initiated at either location and viewed at both.
Units have been in operation since November 1999 with a total of 19,700 hours of control system operation and 3,900 completed transactions. Unit failure has been responsible for less than 1 percent downtime and data corruption has been non-existent. Internet interruptions have resulted in minor delays in transmission of approximately 3 percent of data transmitted. Since system operation isn’t dependent on communication, these interruptions have had no impact on day-to-day operations.
Production of an automated vehicle wash kiosk is both practical and cost efficient. Traditional POE water treatment techniques, including chemical deionizing beds, TDS and pH monitors and newer ones—such as digital computers, the Internet and wireless data transmission—have been combined effectively. Application of these technologies has, for the first time, allowed deionized water to be a true consumer product.
Techniques used for control of traditional large-scale water treatment processes can be successfully adapted to POE applications through use of newer data collection, storage and communication methods. Collaboration of mechanical design, Internet service, wireless communication and software development professionals has made these systems a reality today.
- Western Car Wash Association, “Water Usage Comparison of Car Wash Methods,” 1980, website: http://www.wcwa.org/
- Ehrick, S.D., “Final Report—Water Usage by User Groups with High and Low Experience Levels,” Ionman Wash Systems, Yorba Linda, Calif., Aug. 1, 2000.
About the authors
David Ehrick is operations director of Ionman Wash Systems LLC, a Yorba Linda, Calif.-based company specializing in development and production of high-purity water vehicle cleaning systems. He holds certificates issued by the American Water Works Association (Water Distribution Operator) and the California (Grade 2 Water Treatment Operator).
Stephen Ehrick is president of Ionman Wash Systems LLC and holds a bachelor’s degree in mechanical engineering. He has been involved for the past 23 years in the design, development and manufacture of computer controlled mechanical systems as CEO of a medium-sized aerospace corporation.