Dishwasher

[2] In addition to domestic units, industrial dishwashers are available for use in commercial establishments such as hotels and restaurants, where many dishes must be cleaned.

[9][10] In the United Kingdom, William Howard Livens invented a small, non-electric dishwasher suitable for domestic use in 1924.

It was the first dishwasher that incorporated most of the design elements that are featured in the models of today;[11] it included a door for loading, a wire rack to hold the dirty crockery and a rotating sprayer.

It was the first machine suitable for domestic use, and it came at a time when permanent plumbing and running water in the home were becoming increasingly common.

Initially, dishwashers were sold as standalone or portable devices, but with the development of the wall-to-wall countertop and standardized height cabinets, dishwashers began to be marketed with standardized sizes and shapes, integrated underneath the kitchen countertop as a modular unit with other kitchen appliances.

[15] One feature was use of "soil sensors", which was a computerized tool in the dishwasher which measured food particles coming from dishes.

[16] One notable exception were dishwashers produced by the Maytag Corporation from the late sixties until the early nineties.

This unique design allowed for a larger capacity and more flexibility in loading of dishes and pots and pans.

Stainless steel tubs resist hard water, and preserve heat to dry dishes more quickly.

Such models also tend to use inline water heaters, removing the need for exposed elements in the base of the machine that can melt plastic items near to them.

Some North American machines, primarily those designed by General Electric, use a wash tube, often called a wash-tower, to direct water from the bottom of the dishwasher to the top dish rack.

In such dishwashers the electromechanical rotary switch often used to control the washing cycle is replaced by a microprocessor, but most sensors and valves are still required.

However, pressure switches (some dishwashers use a pressure switch and flow meter) are not required in most microprocessor controlled dishwashers as they use the motor and sometimes a rotational position sensor to sense the resistance of water; when it senses there is no cavitation it knows it has the optimal amount of water.

Some dishwashers include a child-lockout feature to prevent accidental starting or stopping of the wash cycle by children.

With new advances in detergents, lower water temperatures (50–55 °C; 122–131 °F) are needed to prevent premature decay of the enzymes used to eat the grease and other build-ups on the dishes.

In the US, residential dishwashers can be certified to a NSF International testing protocol which confirms the cleaning and sanitation performance of the unit.

Plastic and non-stick items form drops with smaller surface area[20] and may not dry properly compared to china and glass.

US governmental agencies often recommend air-drying dishes by either disabling or stopping the drying cycle to save energy.

Sterling silver and pewter will oxidize and discolour from the heat and from contact with metals lower on the galvanic series such as stainless steel.

Glued items, such as hollow-handle knives or wooden cutting boards, will melt or soften in a dishwasher; high temperatures and moisture damage wood.

Cast iron cookware is normally seasoned with oil or grease and heat, which causes the oil or grease to be absorbed into the pores of the cookware, thereby giving a smooth relatively non-stick cooking surface which is stripped off by the combination of alkali based detergent and hot water in a dishwasher.

According to a peer-reviewed study in 2003, hand washing and drying of an amount of dishes equivalent to a fully loaded automatic dishwasher (no cookware or bakeware) could use between 20 and 300 litres (5.3 and 79.3 US gal) of water and between 0.1 and 8 kWh of energy, while the numbers for energy-efficient automatic dishwashers were 15–22 litres (4.0–5.8 US gal) and 1 to 2 kWh, respectively.

The study concluded that fully loaded dishwashers use less energy, water, and detergent than the average European hand-washer.

The study does not address costs associated with the manufacture and disposal of dishwashers, the cost of possible accelerated wear of dishes from the chemical harshness of dishwasher detergent, the comparison for cleaning cookware, or the value of labour saved; hand washers needed between 65 and 106 minutes.

[34] For example, kilowatt hours of electricity were compared against energy used for heating hot water without taking into account possible inefficiencies.

Also, inefficient handwashings were compared against optimal usage of a fully loaded dishwasher without manual pre-rinsing that can take up to 100 litres (26 US gal) of water.

[35] A 2009 study showed that the microwave and the dishwasher were both more effective ways to clean domestic sponges than handwashing.

In the US, NSF International (an independent not-for-profit organization) sets the standards for wash and rinse time along with minimum water temperature for chemical or hot-water sanitizing methods.

The system may first rinse with pure water only and then sanitize with an additive solution that is left on the dishes as they leave the washer to dry.

[41] Dishwashers also have been documented to be used to clean potatoes, other root vegetables, garden tools, sneakers or trainers, silk flowers,[42] some sporting goods, plastic hairbrushes, baseball caps, plastic toys, toothbrushes, flip-flops,[43] contact lens cases, a mesh filter from a range hood, refrigerator shelves and bins,[44] toothbrush holders, pet bowls and pet toys.