These machines wash soiled tableware. They are designed more for fresh soil like you would encounter in a food service setting where tables are cleared and dishes brought directly to the dishwashing station. My Hobart literature is old, but the various sized models correspond to more modern machines. An older machine the size of the demonstration model would have a pump that circulated 175 gallons per minute which is pretty high water pressure. The small model that has the tank the size of the domestic machines through the 14 series circulated 45 gallons a minute and was the only model that drained the wash water and filled for a recirculated rinse. The small "turtleback" circulated 50 gpm and the larger one 80 gpm. These are the type machine that could often be watched if you were sitting at the counter in Waffle House, Toddle House or similar type restaurant with the kitchen behind the counter. In the single tank machines, only a very brief part of the cycle is devoted to rinsing, usually a minimum of 5 and a maximum of 12 seconds from the upper and lower rinse arms. Since this is fresh water directly from the hot water supply, the water falls into the tank and dilutes the detergent solution. The displaced wash solution drains through an overflow pipe. One of the main reasons for the prerinsing is to keep food soil from breaking down the detergent concentration in the wash tank if the machine does not have a prewash tank since detergent is a great expense in the dishwashing operation. The machine I operated in the hospital kitchen was a flight type with two big doors and three tanks: the prewash or scrapper, main wash and first rinse. Since the machine has the prewash tank, nothing was rinsed, but all food was scraped into a couple of large garbage cans that a pig farmer picked up 3 times a week. The flight type machines had a conveyer belt with rows of pins so everything except glasses and silverware did not need racks and were continuously loaded onto the conveyer. My father told me that experienced personnel could pick up a stack of plates with both hands and load two per row, moving their hands back and forth releasing the plates with their thumbs into each row. Of course, if you did not have someone at the other end removing the clean dishes, the belt would stop until the end of the conveyer was cleared. There were coarse and fine filters in the prewash, wash and first rinse tanks. The final 180 degree spray rinse was triggered by dishes passing a motion sensor. Each tank overflowed back into the one before it to help keep the water clean and hot, although steam boosters heated the main wash and first rinse tanks. Pots and pans were run through the machine and then the remaining food treated before they were sent back through. While I worked there, I do not ever remember washing a pot in a sink except for the huge cast iron skillets.
