E Book. Auto Dish & Glass Washing

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Julian Wright
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1 E Book Auto Dish & Glass Washing

2 Auto Dish & Glass Washing Introduction 1. Introduction 2. Machine Types 3. Temperature & Water Conditions 4. Top 10 Best Practises 5. Chemicals & Dosing 3

1. Introduction The first reliable hand-powered dishwasher was invented in 1887 by Josephine Cochrane (US) and unveiled at the 1893 Chicago World s Fair.

3 1. Introduction The first reliable hand-powered dishwasher was invented in 1887 by Josephine Cochrane (US) and unveiled at the 1893 Chicago World s Fair. The Cochrane s had a busy social life, and in 1870 when they moved into a large home, ideal for entertaining, they regularly entertained guests using heirloom fine china. After one event, when servants carelessly chipped some delicate dishes whilst washing up, Mrs. Cochrane was furious and refused to allow the servants to handle the china again. The result was that, after every subsequent dinner party, she begrudgingly endured dishpan hands wondering why someone had not invented a machine that could clean dirty dishes, when machines had already been invented to sew clothes and cut grass. Consumed by the challenge of inventing an automatic dish washer, she developed the idea of securing the dishes in a rack whilst applying high pressure water to clean them. Her husband William Cochran, who was a rising star in the Democratic Party, died in 1883 leaving a significant amount of debt, so the development of the dishwasher escalated from a project of convenience to a project for survival. Her first creation had wire compartments for plates, cups and saucers which were put inside a wheel that lay flat inside a copper boiler. A motor turned the wheel, pumping hot soapy water from the bottom of the boiler over the dishes, but it didn t really work too well, so she got help with the design from mechanic George Butters, and the first patent on the refined design of the Garis-Cochran Dish-Washing Machine was issued on 28th December,

sprayer. Drying elements were added to his design in 1940.

4 It was much later, in 1924, when William Howard Livens (UK) invented a small dishwasher that was actually suitable for domestic use. This was the first modern dishwasher, and incorporated most of the design elements that feature in the models of today a front door for loading, a wire rack to hold the dirty crockery and a rotating sprayer. Drying elements were added to his design in It was the first machine suitable for domestic use, and it came at a time when permanent plumbing and running water was becoming increasingly common in residential properties. Although there have been many improvements in design and components over the years, the basic functions of a dishwasher are essentially the same as before. A dish or glass washer is simply a machine designed to clean and disinfect plates, cups, glasses, cutlery, utensils, and trays by spraying a detergent solution to clean and a rinse additive to aid drying. By rinsing at high temperature (71*C for 7 seconds), items are 5

5 also disinfected, so a commercial ware washing machine is now a time-saving necessity and valued capital asset for any commercial food and beverage operation. Although large commercial dish washers look daunting and complex, they can be regarded simply as large stainless steel boxes that can wash and rinse items in water that is hotter than can be used safely by hand. When a dish washing machine is first switched on, a solenoid valve (an electrically operated tap) is opened to allow fresh mains water to flow into the Wash Tank where electric elements heat the water to between 55ºC 65ºC. As the wash tank is filling, an initial charge (amount) of chemical detergent is dosed at the appropriate level. We will look at the subject of chemical dosing in a later post within this series. The initial charge is the amount of detergent that is added to the water in the wash tank to achieve a detergent concentration that will clean effectively at optimum levels. The detergent is dosed by a small electric pump and the amount dosed is programmed depending on the site water conditions and other factors (see later post on the impacts of hard water and lime-scale on wash performance). Once the correct amount of water and detergent is in the tank, and the rack of soiled dishes has been placed into the machine, the washing process begins. In the wash process, the hot detergent/water solution is pumped from the wash tank through washing arms, fitted with spray nozzles, mounted above and below the racks of dishes. The pressure of the water jets causes the wash arms to rotate and disperse the spray on to the items being cleaned. In a well-maintained machine, the pressure of the spray is high and the mechanical action of the water striking the soiled surfaces, combined with the chemical action from the detergent, allows effective cleaning. The soiling is either completely emulsified by the hot detergent solution or flushed from the surfaces to be collected on scrap trays situated within the machine for later removal. When the washing stage is complete, the items in the dishwasher are rinsed with clean, hot water. During the rinse cycle a specialised chemical called a rinse aid is dosed into a small boiler in the dishwasher that heats the water to 820C 880C and the hot solution is sprayed onto the items in the racks to flush away any detergent residues and to assist streak free drying. The chemical rinse aid simply speeds up the drying of the items by allowing the hot water to be shed from the surface efficiently without runs or water marks. In later posts we will examine the importance of consistent temperatures and the removal of lime scale in achieving maximum cleaning results. Acknowledgements: invented-the-dishwasher/ 6

2. Machine Types Following the brief overview of the origins and history of the dishwasher presented in Part 1, this post describes the most common types of dish and glass washer machines available

6 2. Machine Types Following the brief overview of the origins and history of the dishwasher presented in Part 1, this post describes the most common types of dish and glass washer machines available to commercial food and beverage operations. We have posted some machine manufacturer links at the end of the post. It is important to note that although machinery and chemical companies are closely linked, they invariably don t work closely enough together. Problems with wash results are routinely directed towards the chemical supplier in the first instance because, in most cases, they will visit the site free of charge, whereas the machinery company will routinely charge for the visit. R.P. Adam collaborates with all machinery suppliers to work in the best interests of their mutual clients. New dish and glass washers can range from 1,000 to 25,000+ so with this significant capital outlay it makes sense to have a preventative maintenance programme set up from the outset. Pumps need maintained, peristaltic tubes need changed and heating elements will degrade and fail over time. Likewise, essential parts such as wash jets, rinse jets and door seals should be maintained and replaced as required. Commercial Under-Counter Dish & Glass Washers (Front Loaders) Also referred to as a front loader type machines, these are perfect for the licensed trade, small retail catering outlets where space restrictions apply and are commonly used on hospital wards. They are built to accommodate different interchangeable plastic racks which come in various sizes and capacities. The relative performance of 7

7 the machine models is normally measured by the number of plates or pint glasses washed per hour. Hood Type Dish Washers The single tank, single cycle pass-through dish washer is one of the most common machine types used today. They are usually configured as a straight through or corner style model and fitted with custom stainless steel tabling for sliding the dishwashing racks directly into and out of the machine. They use different interchangeable plastic racks and the capacity of the machine is measured by the number of plates washed per hour. There is often a sink and overhead pre-spray system fitted alongside these machines to pre-spray loose food debris prior to entry into the machine. Conveyor Type Dish Washers (Rack Conveyors) Also referred to as rack conveyors, they are designed to pull the wash racks through the wash cycle on a chain conveyor. Usually found in larger catering departments such as university refectories, large cafeterias and hospital main catering departments serving between 250 to 1500 meals during peak hours per day. Although the washing capacity depends upon the length of the machine, they usually wash up to 400 racks per hour. 8

Flight Type Dish Washers Also referred to as rack-less, belt conveyor or tunnel machines, they do not use wash racks because the wash items are placed directly onto the conveyor belt.

8 Flight Type Dish Washers Also referred to as rack-less, belt conveyor or tunnel machines, they do not use wash racks because the wash items are placed directly onto the conveyor belt. Most flight type dish washers are individually designed and custom-built for the requirements of each operation and are commonly found in mass catering/banqueting areas, airline catering operations and large hospital main catering departments. The largest machines are capable of washing tens of thousands of dishes per hour. Pot & Pan Washers Pot and pan washers utilise much higher water pressure and longer wash cycle times to remove baked-on food from large pots, pans, baking sheets and food preparation vessels. These are found in food processing factories like commercial bakeries and airline catering operations where there is a requirement for industrial scale cleaning of larger heavily soiled items. Although not an exhaustive list the following machine manufacturers provide good quality equipment for all types of operations: Hobart ( Meiko ( Winterhalter ( 9

3. Temperature & Water Conditions In this post we look at two critical factors that affect wash performance in any dish or glass washer operation maintaining correct wash and rinse temperatures and

9 3. Temperature & Water Conditions In this post we look at two critical factors that affect wash performance in any dish or glass washer operation maintaining correct wash and rinse temperatures and knowing the hardness of the water coming into the machine. Maintaining the correct temperatures is critical in achieving clean dishes or glasses. Optimum WASH temperature: Failure to achieve the correct wash temperature will lead to poor cleaning performance, poor removal of protein residues and possible foaming on an industrial scale! Optimum RINSE temperature: Failure to maintain the correct rinse temperature will result in wet crockery and cutlery, streaking and spotting. For Commercial Dish Washers: Pre-Wash Tank: C Main-Wash Tank: C Rinse Boiler Tank: C Final Rinse: C For Commercial Glass Washers: Main-Wash Tank: C Rinse Boiler Tank: C It is critical that these temperature thresholds are adhered to. A reputable chemical company offering regular field service visits will record the wash and rinse 10

10 temperatures and notify the customer if the temperatures are incorrect. The chemical supplier has no authority to tamper with the dish washer itself, so it is important that the machine manufacturer is contacted to rectify below par temperature settings and delivery. Operators should be aware that every item that enters into a dish or glass washer is colder than the wash water in the tank, therefore the temperature of the wash water will drop slightly after each cycle. If the machine is used continuously without a recovery period to allow the water to be re-heated, cleaning performance is likely to become progressively worse. Note: Some machines have dedicated wash programmes (like laundry machines) that wash at either lower or higher temperatures than those stated above because of specific requirements for example, there may be a dedicated washing programme for polycarbonate glass. Combatting the Effects of Lime-Scale If you live in a hard water area (please see the hard water maps of the UK and UAE below) and look inside your kettle, you will notice a tough, stony, off-white crust inside, particularly surrounding the heating element. This is lime-scale, a mineral deposit left behind when hard water is heated or boiled. Rainwater is naturally soft, containing few impurities and if it runs over/through less permeable rocks like granite or slate, it remains as such. However if rain water runs through soft, spongy rocks, like lime stone or chalk, it absorbs minerals from them. These dissolved minerals, often calcium or magnesium carbonate, are what makes the water hard. Where acid rain precipitates, especially over metropolitan and industrial areas, this process is speeded up considerably. Quite simply it is more difficult to wash in hard water. If you have tried to use soap or shampoo in central London, for example, you may have noticed that the soap does not lather readily and you may have to use more to get the desired effect. In the same way, if the chemicals used are not the right formulations for the water quality, they will be less effective and more will be required. Some of the minerals found in hard water possess a chemical property called inverse solubility, meaning that they dissolve more easily in cold water than in hot. So as the temperature increases, the dissolved salts start toun-dissolve and deposit on surfaces. This is why you normally see the heaviest deposits around the heating element, the hottest part, in a domestic kettle (or dish washer). 11

11 In commercial dish and glass washing, a bigger problem arises if the untreated hard water is heated above 55 C or left to stand. The dissolved minerals within the water will dry out and solidify onto wash jets and metals surfaces as the water evaporates. This solidified mineral coating is lime-scale and is the cause of many problems in both domestic and commercial premises. On an industrial level, the presence of lime-scale makes the machines less energyefficient. According to British Water, a 1.6mm coating of lime scale on a heating element can make it up to 12% less effective. Imagine the impact on a multiple-chain of restaurants, hotels or bars, whose estate is primarily located in hard water areas, incurring a 12% increase in energy costs because of poor machine maintenance/failure to combat lime-scale? Softening Water Reduces the Negative Impacts of Lime-Scale Water softening is the most common method of treating hard water. It works by a fairly simple chemical process swapping the calcium which forms lime-scale for sodium, which is more likely to stay dissolved. In simple terms this is how a commercial water softener works: 1. As water enters the system it passes through an ion exchange column filled with thousands of tiny beads of resin. 2. This resin has charged sodium attached to its surface and it swaps this for the more reactive calcium and magnesium as water flows over it. 3. The resin can continue to do this indefinitely as long as it is washed through with salt water every so often to wash off the calcium and magnesium and replace the sodium. Most modern columns will automatically rinse themselves if regularly provided with salt. Most dish washers have either a built-in softener or a separate water softening dispenser which removes hardness from water and prevents the formation of a white 12

12 film on glassware or crockery. It is vital that staff are aware of the importance of this piece of equipment and know how to replenish the softener. To find out whether your business premises are in a hard water area, please see the maps below: 13

If there is a lime-scale build-up within your dish or glass washer, this can be removed by using an acidic liquid descaler as follows: (http://www.rpadam.co.

13 If there is a lime-scale build-up within your dish or glass washer, this can be removed by using an acidic liquid descaler as follows: ( 1. Switch off the electronic wall mounted dosing equipment (if applicable). 2. Dilute the descaler with up to 20 parts water depending on the degree of scale build up and add directly into the wash tank. 3. For best results, heat up the water to working temperature and circulate until all scale is removed. 4. Drain solution, refill and rinse thoroughly with clean water. 5. Drain again and refill with clean water. 14

4. Top 10 Best Practises Many of the negative impacts affecting dish and glass washing results can easily be overcome by adhering to some very basic rules like thorough pre-scrapping, prerinsing

14 4. Top 10 Best Practises Many of the negative impacts affecting dish and glass washing results can easily be overcome by adhering to some very basic rules like thorough pre-scrapping, prerinsing (above photo) and effective racking and stacking. Here are some key issues to address: 1. Scrape all food debris from plates and ensure all heavily soiled items are prerinsed prior to entering the machine. Always remove solid debris like cocktail sticks, fruit peel, pips, paper etc. from glasses and plates. They can block the wash jets and impair performance. 2. Rack items of the same size together so none are hidden from wash jets. Fill the racks evenly but not too tightly making sure items are well-spaced so that the wash solution gets an even coverage. 3. When loading glassware always ensure that the baskets are filled to capacity to minimise breakages and place cups and glasses upside down to allow the wash water to spray in from below. Always stand glasses on drip mats to dry. 4. Allow crockery to air dry never use a tea towel as it can harbour bacteria and may contaminate the items which have already been thermally disinfected. 5. Always mix different types of cutlery in baskets to avoid items sticking together and ensure that they are stacked in baskets with the handles down eating end up. 6. All pots and pans and larger utensils should be washed by hand unless there is a dedicated pan washer for larger items. 15

15 7. Remember to dump the wash water after each session and refill with fresh water, otherwise the machine will be re-circulating dirty water. 8. Ensure that the filter trays within the machine are checked and cleaned so that larger items of debris do not re-circulate and impede the wash performance. 9. Ensure that the machine wash and rinse jets are cleaned on a weekly basis and are free of food debris, broken glass and lime-scale. If these jets are blocked the wash water will not make effective contact with the items to be washed. 10. In hard water areas where lime-scale is a problem, ensure that the machine is descaled once a week with a liquid phosphoric acid descaler. Lime-scale build up will significantly reduce the efficiency of the machine and will consume far more energy than normally required. The dish and glass washer needs cleaned like any other piece of catering equipment or surface, so ensure you clean thoroughly the inside of the machine after each session: 1. Shut off machine at the mains supply and not just on the machine. 2. Open the drain plugs to empty the machine completely. 3. Remove the curtains and clean with a degreaser/sanitiser. 4. Remove both wash and rinse arms and clean out all debris. 5. Remove scrap trays and clean out all debris. 6. Thoroughly clean out the inside of the machine with a degreaser/sanitiser and rinse thoroughly. 7. Replace scrap trays, wash and rinse arms and curtains. 8. Shut doors and switch on and allow machine to heat up to correct working temperature. 9. Machine is now ready to operate. 10. Ensure no broken parts (like missing wash & rinse jets for example). 16

5. Chemicals & Dosing In this post we look at chemicals and chemical dosing. For best results, commercial dish washers are normally fitted with electronic dosing pumps to dispense the chemicals.

16 5. Chemicals & Dosing In this post we look at chemicals and chemical dosing. For best results, commercial dish washers are normally fitted with electronic dosing pumps to dispense the chemicals. Electronic chemical dosing pumps are programmed to allow dish washer detergent and rinse additive to be metered precisely and consistently into the correct wash cycle. There are two methods of pumping detergent and rinse aid into a dish or glass washer: 1. Via pumps located within the design of the washing machine itself this is called integral feed and these are usually found on smaller capacity machines like cabinet glass washers. The pumps are pre-set by the machine manufacturer to try to accommodate most liquid chemicals available on the market. This often means that the pumps dose more chemical than required for optimum cleaning. The chemical manufacturer therefore only supplies the chemical and has no real input into dose levels. 2. Via external dosing pumps which are usually provided Free-On-Loan by a reputable chemical manufacturer who will fit the dosing unit and set the dose rates for their specific chemicals and tailored to site requirements. 17

There are different types of electronic dosing systems available but most chemical suppliers use timed (or cyclic) dosing to get their products into the wash tanks in a controlled manner.

17 There are different types of electronic dosing systems available but most chemical suppliers use timed (or cyclic) dosing to get their products into the wash tanks in a controlled manner. Calculated chemical dose levels are pre-set by the chemical manufacturer to ensure the optimum concentration of chemical is used in each wash cycle, taking into account the amount of water in the wash tank and the volume of water added in the rinse cycle. The pumps are then calibrated and dose levels are programmed into the memory of the dosing unit to ensure that the correct amount of chemical detergent and rinse aid is added every time. In future posts we will examine the pros and cons of timed dosing versus probe based dosing. In simple terms this type of dosing is based on the premise that a probe (located in the wash tank) detects the concentration of chemical available. If the concentration is too low, it asks for more and the pumps dose additional detergent to the required level. If the probe s detection sensitivity is compromised (by being scaled up or enveloped in debris) it will falsely ask for more detergent when it is not required, meaning the machine asks for more than is required. Although not an exhaustive list the following dosing unit manufacturers provide good quality equipment for all types of operations: Brightwell Dispensers ( Dema ( Knight ( Seko ( It is also worth considering setting up a preventative maintenance schedule with your chemical supplier, who will check, service and maintain chemical dosing units on a regular basis. A reputable chemical manufacturer will have an experienced team of service personnel who will routinely change pump heads and peristaltic tubing to 18

18 ensure consistent dosing and will have access to qualified electrical engineers to fit and repair sophisticated dosing equipment. The supplier should regularly conduct titration tests of the wash tank solution to ensure the correct chemical concentration levels are being maintained. They should also conduct temperature tests so that clients have hygienically clean and dry crockery, cutlery and glassware. Wasted time is wasted money; therefore a prompt, reliable, efficient and professional engineering function from your chemical supplier is essential to maintain the operational efficiency of a commercial dishwashing operation. Customers need to know that if a breakdown is reported it is dealt with in a prompt and efficient manner to ensure as little downtime as possible for the operator. For further information on the types of chemicals available for automatic dish and glass washing click here ( Both RP Adam and Arpal Gulf (following the completion of a new account installation) operate systems whereby a schedule of on-going service calls is automatically generated, thus offering customers unrivalled engineering support. Our technicians vehicles are well stocked with a wide variety of equipment, spares and tools, ensuring that work can be completed at the first visit. Our objective is always the same complete the work first time, every time. It should be noted that the automatic dish, glass and pot wash detergents that are automatically dosed into machines are almost all corrosive to the eyes and skin, so great care should be taken when handling these types of products and the appropriate eye and skin protection used. As safety is our primary focus at all times, we will shortly be unveiling a brand new Ultra-Safe liquid dish and glass washing system watch this space. 19

Food & Beverage STEWARDING MANUAL CHIEFS MANUAL & SOP S

Food & Beverage STEWARDING MANUAL CHIEFS MANUAL & SOP S Index F&B Manual, Kitchen Section 5 (Stewarding) Part 1, Guidelines for Chief Ware washing and Decoy System Scraping and Racking Dishwashing Machine