Machine dishwasher is a mechanical device for cleaning cutlery and tableware. Unlike manual dishwashing, which relies heavily on physical scrubbing to remove impurities, mechanical dishwashers clean by spraying hot water, usually between 45 and 75 ° C (110 ° and 170 ° F), on a plate, with lower temperatures used for delicate items.
A mixture of water and dishwashing detergents is pumped into one or more spinning spray arms, which blow up the plate with a mixture of cleansers. After the washing is done, the water is drained, more hot water enters the tub through the electro-mechanical solenoid valve, and the rinse cycle begins. After the rinsing cycle is complete and the water is dried, the plate is dried using one of several drying methods. Usually rinse aid, chemicals to reduce water surface tension, are used to reduce water spots from hard water or other reasons.
In addition to domestic units, industrial dishwashers are available for use in commercial companies such as hotels and restaurants, where a large number of dishes must be cleaned. Washing was done at temperatures of 65-71Ã, Â ° C (149-160Ã, Â ° F) and sanitation was achieved by either the use of a booster heater that would provide "final flushing" of 82 ° C (180 ° F) temperature or through use chemical cleaning agents.
Video Dishwasher
Use
The user operates a dishwasher by placing a dish on a dishwasher rack, adding dishwashing detergent, switching on the device, then removing the clean plate after the cycle is over.
The use of dishwashing begins with the installation of tools. Most home users fix their dishwasher in one place, like under the table. However, a portable machine is available that can be rolled into the sink, with a hose attached to the kitchen sink faucet.
For dishwashers with a built-in food waste disposer, pre-rinsing or scratching is not required. Large wastes are tilted from the plate before loading. For machines that do not have built-in food waste disposal, users scrape the plate before loading. Since the early 1960s, manufacturers have designed consumer dishwashers for use without pre-rinsing or pre-washing. Soft food waste is milled by the machine and then disposed of with waste water. In the early eighties, machines were introduced with "hard-food waste" that could erode heavier food waste such as grains, popcorn stomach, etc. Dishwashers are designed to store a variety of dishes in different places. For the two most common dishwasher dishwasher installed, the user loads cups, bowls, and small dishes onto the top shelf. Tableware goes into the bottom shelf into a container, with a pointy tip for safety. Some manufacturers use reverse rack loading, with plates, large plates, and equipment loaded on the top shelf, while smaller glasses and items go down the shelf. Some dishwashers have a third rack for equipment. Heavier plates enter the bottom shelf, with large pots facing down toward the nozzle nozzles. After the dishwasher is loaded, the user puts dishwashing detergent into the machine. Many contemporary dishwashers use sensors to determine how much water, time and temperature are required.
Dishwashers and detergents used in dishwashers are not designed for use with some materials. Heat and wash cycle chemicals can damage kitchen knives and non sticky surface pans. Detergents have their own use restrictions, including unsafe to clean various materials such as wood or metal.
Maps Dishwasher
History
The first mechanical washers were registered in 1850 in the United States by Joel Houghton. This tool is made of wood and is turned on by hand while water is sprayed onto the plate. This device is slow and unreliable. Other patents granted to L.A. Alexander in 1865 was similar to the first but featured a hand-cranked rack system. No device is practical or widely accepted.
However, the most successful hand-held dishwasher was discovered in 1887 by Josephine Cochrane along with George Butters mechanic at Josephine's toolhouse in Shelbyville, Illinois when Cochrane (a wealthy socialite) wanted to protect her portion while being washed. His invention was inaugurated at the 1893 World Exposition in Chicago, Illinois under the name Lavadora but was changed to Lavaplatos because another machine invented in 1858 already held that name. This machine is what is now known as a washing machine. Cochrane's inspiration was his frustration at the damage to his fine porcelain stuff that happened when his servants dealt with it while cleaning.
The first domestic dishwasher in Europe with an electric motor was invented and manufactured by Miele in 1929.
In the United Kingdom, William Howard Livens created a small, non-electric dishwasher that was suitable for domestic use in 1924. It was the first dishwasher to incorporate most of the design elements featured in today's models; it includes a front door for loading, a wire rack to hold dirty breaking equipment and spinning sprayer. The elements of drying were even added to its design in 1940. This was the first machine to be suitable for household use, and it came at a time when permanent pipes and water flowing at home became increasingly common.
Nevertheless, Liven's design did not become a commercial success, and dishwasher was only successfully sold as a domestic utility in the post-war explosion of the 1950s, though only for the rich. Initially the dishwasher was sold as a standalone or portable device, but with standard desk-to-wall development and wardrobe cabinets, dishwashers began to be marketed to standard sizes and shapes, integrated under the kitchen table as a modular unit with other kitchens. equipment.
In the 1970s, dishwashers had become commonplace in domestic homes in North America and Western Europe. In 2012, more than 75 percent of homes in the United States and Germany have dishwashers.
In the late 1990s, manufacturing began offering a variety of new energy conservation features in dishwashers. One feature is the use of "ground sensors", which are computerized devices in dishwashers that measure food particles derived from plates. When the dishwasher cleans the plate until it does not remove more food particles, the soil sensor will report that the plate is cleaned. The sensor is operated with another innovation using the washing time variable. If the dishes are so dirty, then the dishwasher will run longer than if the sensors detect them clean. In this way, the dishwasher saves energy and water by simply operating for as long as it takes.
Design
Size and capacity
Dishwashers fitted to standard kitchen cabinets have a standard width and depth of 60Ã,® cm (Europe) or 24Ã, "inches (USA), and most dishwashers must be fitted into a minimum of 86Ã,® (Europe) or 34Ã, inch (US) ) is high. Portable dishwasher is in the 45 and 60 cm (Europe) or 18 and 24 inch (USA) width, with casters and countertops attached. Dishwashers can come in standard or high bathtub designs; a standard kitchen sink has a service kickplate under the door of a dishwasher that allows for simpler maintenance and installation, but a high-capacity dishwasher bath has a capacity of about 20% more and better soundproofing than having a sustainable front door.
International standards for dishwasher capacity are expressed as standard place settings. Commercial dishwashers are rated as plates per hour. Ratings are based on standard sized plates of the same size. The same can be said for commercial glass washers, since they are based on standard glasses, usually pint glasses.
Layout
Today's machines have front-panel drop-down doors, allowing access to the interior, which usually contains two or sometimes three shelves; the shelf can also be called a "basket". In older US models from the 1950s, the entire bathtub was rolled out when the latch was opened, and loading/removing washable items came from above, with the user reaching deep into the compartment for some items. The Youngstown Kitchen, which produces all the kitchen cabinets and sinks, offers a tub-style dishwasher, which is incorporated into a conventional kitchen sink as a unit. Most machines today allow for placement of plates, silverware, high goods and cooking utensils on lower shelves, while glasses, cups and plates are placed on the top shelf. One exception was the dishwasher produced by Maytag Corporation from the late sixties to the early nineties. These machines are designed to load glasses, cups and saucers on the bottom shelf, while plates, silverware and high goods are placed onto the top shelf. This unique design allows for greater capacity and more flexibility in loading dishes and pots and pans. Currently, the "draw drawer" model eliminates the discomfort of the required long range with the older deep model. "Cutlery" is also common. Dishwasher drawer, first introduced by Fisher & amp; Paykel in 1997, was a variant of a dishwasher where baskets slid out the door in the same way as a file cabinet, with each drawer in a double drawer model operating independently of the others.
The interior of the dishwasher in the North American market is stainless steel or plastic. The stainless steel tub holds the water hard, and retains heat to dry the plate faster. They also come with a premium price. The old model uses a baked enamel bathtub, while some use a vinyl coating tied to a steel tub, which provides bathtub protection from acidic foods and provides some voice attenuation. Dishwasher made in Europe featuring stainless steel interior as standard, even on low-end models. The same applies to the built-in water softener.
Wash element
European dishwashers almost universally use two or three spray arms fed from the bottom and back wall of a dishwasher that let both shelves be unobstructed and also such models tend to use inline water heaters, eliminating the need for open elements at the base of the machine can melt plastic items near them. Many North American dishwashers tend to use open elements at the bottom of the dishwasher. Some North American machines, especially those designed by General Electric, use washing tubes, often called towers, to direct water from the bottom of the dishwasher to the top plate rack. Some dishwashers, including many models from Whirlpool and KitchenAid, use tubes attached to the top shelf that connect to the water source at the rear of the dishwasher, and direct the water into the second wash under the top rack, allowing full use of the lower shelf. Late-model Frigidaire dishwashers fire water jets from the top of the washer downward to wash the arms, again allowing full use of the bottom shelf (but requiring that the small funnel on the top shelf be clearly guarded).
Features
Mid-to-high end North American dishwashers often come with a hard-food dumping unit, which behaves like a mini-waste disposal unit (waste) that removes large chunks of leftover food from washing water. One manufacturer known to eliminate the release of hard foods is Bosch, a German brand; however, Bosch does it to reduce noise. If larger items of food waste are discarded before being placed in a dishwasher, pre-rinsing is not required even without an integrated waste disposal unit.
Many new dishwashers feature controlled microprocessors, a sensor-assisted wash cycle that adjusts leaching duration to the quantity of dirty dishes (perceived by changes in water temperature) or the amount of impurities in rinse water (felt chemically or optically). This can save water and energy if the user runs some of the load. In the dishwasher the electromechanical rotary switch which is often used to control the washing cycle is replaced by the microprocessor, but most of the sensors and valves are still needed. However, pressure switches (some dishwashers using pressure switches and flow meters) are not required in most microprocessor-controlled dishwashers because they use motors and sometimes rotation position sensors to sense water resistance; when he feels no cavitation, he knows he has the optimal amount of water. A bimetal switch or wax motor opens the detergent door during the washing cycle.
Some dishwashers include a child locking feature to prevent accidental starting or stopping child wash cycles. The child key can sometimes be entered to prevent small children from opening the door during the washing cycle. It prevents accidents with hot water and powerful detergents used during the washing cycle.
Process
Energy usage and water temperature
In the EU, the consumption of dishwasher energy for standard usage is indicated on the EU energy label. In the United States, energy consumption of dishwashers is determined using energy factor.
Most consumer dishwashers use a 75Ã, ° C (167Ã,  ° F) thermostat in the sanitization process. During the final flushing cycle, the heating element and the washer pump are switched on, and the cycle timer (electronic or electromechanical) is stopped until the thermostat trips. At this point, the cycle timer will return and will generally trigger the discharge cycle in some timer increments.
Most consumer dishwashers use temperatures of 75 ° C (167 ° F) rather than 83 ° C (181 ° F) for reasons of burning, energy and water consumption, total cycle times, and possible damage to plastic items which is placed in a dishwasher. With the new advances in detergents, lower water temperatures (50-55 ° C/122-131 ° F) are required to prevent the decay of enzymes used to eat fat and other buildup on plates.
In the US, residential dishwashers can be certified for the NSF International testing protocol that confirms the cleaning and sanitizing performance of the unit.
Drying
The heat inside the dishwasher dries the contents after the final hot rinse; the final rinse adds a small amount of rinse aid to the hot water, as this increases drainage significantly by reducing the surface tension attached to the water. Plastic and non-stick items fall on smaller surfaces and may not dry well compared to porcelain and glass, which also store more heat that evaporates a little more water left over. Some dishwashers combine the fan to improve drying. Old dishwashing with visible heating elements (at the bottom of the wash cabinet, under the bottom basket) can use heating elements to improve drying; However, this uses more energy.
Dishwashers of North America tend to use heat-assisted drying through open elements. European engines and some sophisticated engines in North America use passive methods to dry - stainless steel interiors help this process and some models use heat exchange technology between the inner and outer shells to cool interior walls and accelerate drying. Most dishwashers have a drying sensor and hence, dishwashing cycles are always considered complete when a drying indicator, usually in the form of illuminated "final" light, or in a more modern model on a digital screen or audible sound, exhibits to the operator that the cycle washing and drying is now over.
Government agencies often recommend an air drying dish either by disabling or stopping the drying cycle to save energy.
Difference between dishwasher and hand wash
Dishwasher detergent
Dishwashers are designed to work using specially formulated dishwashing detergents. Over time, many regions have banned the use of phosphates in detergent and phosphor-based compounds. They were previously used because they have properties that help in effective cleansing. The concern is the increase of algal blooms in waterways caused by elevated levels of phosphate (see eutrophication). Seventeen US states have partial or total restrictions on the use of phosphates in dish detergents, and two US states (Maryland and New York) ban phosphates in commercial dishwashers. Detergent companies claim it is not cost-effective to make detached batches of detergent for countries with phosphate bans (though detergents are usually formulated for local markets), and so most have voluntarily removed phosphates from all dishwashing detergents.
In addition, rinse aids contain nonylphenol and nonylphenol ethoxylate. It has been banned in the European Union by EU Directive 76/769/EEC.
In some areas depending on the hardness of water, dishwasher may function better by using dishwashing salt.
Glassware
Glass washed with dishwasher can develop a white mist on the surface from time to time. This may be due to any or all of the processes below, where only the first one can be returned:
- Mineral deposition
- Calcium carbonate (sandstones) in hard water can be stored on the surface when water dries. Deposits can be dissolved with vinegar or other acids.
- Silicate screen, etching, and accelerated crack corrosion
- The film begins as a color effect or "oil film" on a glass, and develops into a "milk-like" or "cloudy" (non-deposit) appearance that can not be polished or removed like limestone. It is formed because the detergent is very alkaline (base) and the glass dissolves slowly in an aqueous aqueous solution. It becomes less soluble in the presence of silicates in water (added as an anti-metal-corrosion agent in dishwashing detergent). Since cloudy appearance is due to the non-uniform glass dissolution, it is (somewhat paradoxically) less characterized if dissolution is higher, ie if silicate-free detergent is used; also, in certain cases, etching will mainly be seen in areas that have microscopic surface fractures as a result of the manufacture of goods. This unwanted reaction limitation is possible by controlling water hardness, detergent load and temperature. This type of glass is an important factor in determining whether this effect is a problem. Some dishwashers can reduce this etching effect by automatically removing the correct amount of detergent throughout the wash cycle based on the water hardness programmed.
- Dissolution of lead
- Lead in lead crystal can be converted to a high temperature soluble form and a strong alkaline detergent from a dishwasher, which can harm the health of the next user.
Other materials
Materials other than glass are also harmed by strong detergents, strong agitation, and high temperature dishwashers, especially in hot washing cycles when temperatures can reach 75 Ã, Â ° C (167Ã, Â ° F). The items of aluminum, brass, and copper will discolor, and light aluminum containers will mark other items that they hit. The nonstick pan coating will worsen. The shimmering, golden, and hand-painted items will become dull or faded. Fragile items and sharp edges will be dull or damaged by colliding with other items and/or heat stress. Sterling silver and lead will oxidize and change color from heat and from contact with lower metals in galvanic series such as stainless steels. Pewter has a low melting point and can be curved in some dishwasher. Glued items, such as threaded knives or wood cutting boards, will melt or soften in the dishwasher; high temperatures and wood damaging moisture. High temperatures ruin many plastics, especially on lower shelves close to open heating elements (many newer dishwashers have heating elements hidden away from the bottom shelf entirely). Squeezing plastic objects into small spaces can cause plastic to change shape. Cast iron cookware is usually flavored with oil or fat and heat, which causes oil or fat to be absorbed into the pores of the cookware, thus providing a relatively smooth non-stick cooking surface stripped by a combination of alkali-based detergent and hot water in the machine dishwasher.
Knives and other cookware made of carbon steel, semi-stainless steel such as D2, or a very hard special tool steelware like ZDP189 are corrosive in extended baths of the dishwasher, compared with shorter wash hands. Cookware is made of austenitic stainless steel, which is more stable.
Items contaminated by chemicals such as wax, cigarette ash, poison, mineral oil, wet paint, oiled tools, furnace filters, etc. Can contaminate dishwashers, because surfaces inside small waterways can not be cleaned because of their surface in hand washing. , so contaminants still affect future loads. The objects contaminated by the solvent can explode in the dishwasher.
Environmental comparison
Dishwashers use less water, and therefore less fuel to heat water, than washing hands, except for small amounts washed in a washing bowl without water flowing.
Handwashing techniques vary according to the individual. According to research conducted in 2003, hand washing and drying dishes equivalent to a full automatic dishwasher (no cookware or bakeware) can use between 20 and 300 liters (5.3 and 79.3 liters) of water and between 0.1 and 8 kWh of energy, while the numbers for automatic energy-saving dishwashers are 15-22 liters (4.0-5.8 US gal) and 1 to 2 kWh, respectively. This study concludes that dishwasher dishwashers use less energy, water, and detergents than European handwashing machines. For automatic washing results, plates are not rinsed before loading. This study does not address costs associated with the manufacture and disposal of dishwashers, the cost of the possible use of accelerated wear of hard chemicals of dishwashing detergents, comparisons for cleaning utensils, or the value of labor stored; hand washing is required between 65 and 106 minutes. Several points of criticism in this study have been put forward. For example, kilowatt hours of electricity are compared with the energy used to heat hot water regardless of possible inefficiency. Also, inefficient human washers are compared with the use of an optimum full dishwasher without manual pre-rinse which can take up to 100 liters (26 gallons) of water.
A 2009 study showed that microwaves and dishwashers are a more effective way to clean domestic sponges than washing hands.
Adoption
Commercial use
Large and heavy dishwashers are available for use in commercial establishments (eg hotels, restaurants) where a large number of dishes must be cleaned.
Unlike residential dishwashers, commercial dishwashers do not use drying cycles (commercial drying is achieved by open air heating after the wash/rinsing/sanitation cycle has been completed) and thus significantly faster than their housing counterparts. Washing is done at temperatures of 65-71Ã, Â ° C/150-160Ã, Â ° F and sanitation is achieved by using a booster heater that will provide a "final flushing" temperature of 82 Â ° C/180 Â ° F engines through the use of chemical cleaning agents. This distinction labeled machines as "high-temp" or "low-temp".
Some commercial dishwashers work in conjunction with commercial car washes, with pulley systems that pull shelves through small spaces (widely known as "shelf conveyor" systems). Single rack washers require the operator to push the rack into the washing machine, close the door, start the cycle, and then open the door to pull the cleaned rack, possibly through the second opening into the loading and unloading area.
In the UK, the UK Standard Institutions set standards for dishwashers. In the US, NSF International (an independent non-profit organization) sets standards for washing and rinsing time along with minimum water temperatures for chemical or hot water sanitation methods. There are many types of commercial dishwashers including under the desk, single tank, conveyor, flight type, and carousel machine.
Commercial dishwashers often have significantly different piping and operations than home units, where there are often separate spray guns for washing and rinsing/cleaning. The washing water is heated with an electric heat element in the tank and mixed with a cleaning solution, and is used repeatedly from one load to the next. The washing tank usually has a large filter basket to collect food debris, and the filter may not be emptied until the end of the day's kitchen operation.
Water used for rinse and sanitation is generally delivered directly through the provision of clean water, and can not be reused. The rinsing water used falls into the washing tank reservoir, which dilutes some of the washing water used and causes small amounts to flow out through the overflow tube. The system can first be rinsed with pure water only, and then clean it with the additive solution remaining on the plate as they leave the dry washer.
Additional soaps are periodically added to the main washing water tank, from large soap concentrate tanks or dissolved from large solid soap blocks, to maintain the effectiveness of cleaning of washing water.
Alternate use
Dishwashers can be used to cook certain foods, especially salmon. They can clean toothbrushes, toys, some sporting goods, switchplate covers, ventilation covers, and grilles.
See also
- Home tools
- Washing machine # Manufacturer and brand
References
External links
- "How Dishwasher Works" in HowStuffWorks
- Save energy (and thus carbon footprint)
Source of the article : Wikipedia
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