page_title: Car wash
section_title: Conveyorized/tunnel car wash
hierarchical_section_title: Car wash / Automatic car wash / Conveyorized/tunnel car wash
caption_attribution_description: English: A typical car wash found in Tennessee and nearby states.
context_page_description: A car wash or auto wash is a facility used to clean the exterior and, in some cases, the interior of motor vehicles. Car washes can be self-serve, fully automated, or full-service with attendants who wash the vehicle. It may also be an event where people pay to have their cars washed by volunteers as a method to raise money for some purpose.
context_section_description: The first conveyorized automatic car wash appeared in Hollywood, CA in 1940. Conveyorized automatic car washes consist of tunnel-like buildings into which customers (or attendants) drive.
  Some car washes have their customers pay through a computerized POS, or point of sale unit, also known as an "automatic cashier", which may take the place of a human cashier. The mechanism inputs the wash PLU into a master computer or a tunnel controller automatically. When the sale is automated, after paying the car is put into a line-up called the stack or queue. The stack moves sequentially, so the wash knows what each car purchased. After pulling up to the tunnel entrance, an attendant usually guides the customer onto the conveyor. At some washes, the system will send the correct number of rollers automatically, based on tire sensors. The tire sensor lets the wash know where the wheels are and how far apart they are. On other systems the employee may guide the customer on and press a 'Send Car' button on the tunnel controller, to manually send the rollers which push the car through.
  Prior to entering the automated section of the wash tunnel, attendants may prewash customers' cars. This process can consist of a wide range of manual cleaning procedures, including applying specialized bug removing cleaning agents to various parts of the car, performing a manual high pressure prewash (possibly focusing on areas which the tunnel cannot sufficiently clean), and using manual brushes to scrub down areas of the vehicle which are difficult for the equipment to clean. Manual prewashing may be more extensive if a vehicle has mud or if the customer purchases an upgrade.
  When the customer is on the conveyor, the attendant (or signage) will instruct the customer to put the vehicle into neutral, release all brakes, and refrain from steering. Failure to do so can cause an accident on the conveyor. The rollers come up behind the tires, pushing the car through a photogate, which measures vehicle length, allowing the controller to tailor the wash to each individual vehicle. Some car washes may also use ultrasonic profiling systems to determine the height or width of a vehicle, or to detect open pick-up truck beds. The equipment frame, or arches, vary in number and type.
  The car wash will typically start cleaning with chemicals called presoaks applied through special arches. These arches often use nozzles positioned to spray chemicals in a bi-directional pattern.  In many cases, presoak arches are designed to foam the presoak prior to its application to the car. They may apply a higher pH (mild alkali) followed by a lower pH (mild acid) or vice versa. Chemical formulas and concentrations may also vary based upon seasonal dirt and film on vehicles, as well as exterior temperature, and other factors.  Chemical dilution and application works in combination with removal systems based on either high pressure water, friction, or a combination of both.  One or more sets CTAs, or "chemical tire applicators," are often found near the presoak arches.  These will apply specialized formulations, which remove brake dust and build up from the surface of the wheels and tires.  In many cases, CTAs will only activate if the customer has purchased a wheel cleaning upgrade. Special presoaks may be applied if the customer purchases an upgrade. Extra presoaks are typically applied via a "lava" or "sheet"-style foamer to provide more of a show for the customer.
  After the presoak application, a car wash tunnel's layout can vary greatly.  In some car washes, presoak application is followed by an empty space, or idle zone.  This provides time for the presoak to loosen dirt on the car.  In many cases, wheel cleaning equipment, such as sill brushes or high pressure wheel blasters, are placed in the idle zone.  A sill brush (also known as a wheel brush or tire brush) consists of an 8-foot-long brush assembly which is pushed against the car's wheels and door sill area. Sill brushes are typically use flagged bristle, as dirt is usually most heavily concentrated on the lower parts of
caption: A glass car wash building containing an inbay automatic and freestanding blowers
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