DESIGN AND FABRICATION OF COMMERCIAL UTENSIL STERILIZER PROJECT REFERENCE NO.: 38S1596 COLLEGE : BMS INSTITUTE OF TECHNOLOGY AND MANAGEMENT BANGALORE BRANCH : MECHANICAL ENGINEERING GUIDE : MR. SUNDARESH S STUDENTS : MR. KARTHIK B G MR. HARISH S MR. ARUN KUMAR PATEL MS. RAMYA S S Keywords: Commercial Utensil Sterilizer, Dishwashers, sterilization, Pressurized water wash, UVC photolysis, Introduction Food serving atmosphere plays a very important role in determining the health of the society. We all know that a large number of people depend on hotels for their food daily. Therefore it s very important to make sure that the food will be served in hygienic utensils. Uncleanly utensils results in causing food borne diseases such as food poisoning, hepatitis etc. As we all know most of the hotels, hotels, canteens etc. depend upon manual cleaning for cleaning of utensils. The manual labor assigned for this purpose would be working under tremendous pressure as these food serving places would be in higher demand during certain time of the day. This results in incomplete cleaning of utensils and customer dissatisfaction etc. To overcome this problem now a day many of these industries are going for serving food on plastic sheet laid utensils. This may seem to be a simple solution but we should also consider the amount of wastage generated because of this idea. As we all know in places like Bangalore it s difficult to allot place for disposal of these wastes which will be generated in the quantities of tons per day and most importantly they are not bio degradable. It also have adverse effect on the users health as it possess a serious threat of melting when used to serve hot food items.
Dishwashers exist in market since very long time. But we can observe that none of the small or medium scale hotels, canteens, hostels etc. is employing them. These factors lead us to the design and fabrication of commercial utensil sterilizer. The basic idea is to make the dishwasher user friendly and adoptable to the practical conditions faced in food serving industries and also the hygienic food serving atmosphere is achieved. Objective The main objective is to design and fabricate a commercial utensil sterilizer to clean and sterilize the utensils used in food processing industries, hotels, restaurants etc. and hence ensure the use of hygienic utensils. The objectives of the present work are To study the dishwashers or utensil sterilizers available in the market. To design the different stages of sterilization process. To design the different components. To fabricate the different components and assemble. To test the sterilizer under different operating conditions and hence ensure cleanliness and hygienic state of utensils. Methodology Market research will be carried out regarding the existing dishwashers and sterilizers in the market. Designing step wise sterilization process to overcome the drawbacks. Water cleaning is performed in which the utensils are subjected to high pressure water jet helps in removal of any strains present on the surface. Utensils are exposed to Ultraviolet rays which eliminates the micro-organisms present on the surface. Fabrication of components involved in the above stages/process is carried out. Different components will be assembled. Sterilizer will be tested under different operating conditions.
Designing of process In the first stage the entire process is designed by keeping the objectives in mind and also to make it as much user friendly and adoptable as possible. Overall principle The principle consists of two step cleaning mechanism that is first to loosen the solid particle and then remove using the mechanical action of scrubbing in case of human washing. In this machine the same principle is adopted. The loosening of solid particles from the surface is performed by pouring soap water onto the utensils. The soap water contains detergents mixed with water in desired proportion and hot water is poured to loosen the oil stains and sticky materials from the surface. The mechanical action is carried out by pressurized water jets. The water jets that are used to pour water onto the utensils are pressurized to perform the mechanical action. The pressurized particles apply kinetic energy on the surface and remove the loosened solid particles. The high pressure is generated by the pump and is supplied to the sprayers. In the next step sterilization is carried out. This occurs in two steps, they are 1. Hot water wash 2. UV sterilization Hot water is also poured under high pressure to perform the washing as well as sterilization. The utensils are then subjected to exposure of ultraviolet light. Ultraviolet light carry out sterilization by disabling the reproducibility of RNA. Ultraviolet light is produced using proper light source and the utensils are exposed to it for a stipulated duration, thereby undertaking the sterilization. Pressurized water wash A high pressurized water jet is used to wash the utensils in this stage. The water jet sprays soap water mixture formed in a soap water tank. Utensils are arranged in a tray and the tray is placed in working chamber. Soap water is sprayed onto the utensils using water sprayers. The pressure is generated by a pump; the pressurized water is then sprayed through water sprayers which consist of large number of
holes which also act as nozzles. The pressurized water performs the functions such as loosening of solid particles as well as removing them since the pressure is applied. Soap water washing The soap water needed for washing is prepared in a chamber called soap water chamber. The chamber is a circular container made up of sheet metal. A door is provided at the top for adding cleaning agent. The water level in the chamber is monitored by a ball valve. Main water supply line is connected to the tank and monitored by the ball valve. The cleaning agent is mixed with the water in the prescribed proportion. The cleaning agent specifications and details regarding the working are provided below. Cleaning agent is added periodically for efficient cleaning of utensils. In the chamber water is mixed with cleaning agent in the ratio of 1:100. Water is drawn from a hose connected at the bottom of the container through a pump. Hot water washing Hot water washing is the primary sterilizing step incorporated. The hot water is been used for sterilizing utensils since decades. But this alone wouldn t be enough to solve the purpose, and also it needs an additional set up. Hot water washing undertakes the sterilization by killing the bacteria. Bacteria are killed because they can t survive the higher temperature of the hot water. It also increases the cleaning efficiency by increasing the working rate or efficiency of cleaning agent. The temperature of water used is the most important criteria for effective sterilization. It s been studied that past 145 degrees Fahrenheit, water easily and quickly kills bacteria. Ultra violet sterilization UVC can be used as the exclusive solution in some applications, it is often used in tandem with other techniques. It follows that a single technology solution approach is unlikely to be ideal. It also follows that since UVC is so simple and energy effective, it is perhaps wise to consider this option first. Microorganisms such as bacteria, moulds, yeast s and protozoa can be destroyed or removed by physical, biological and chemical methods. UVC works using a photolytic effect whereby the radiation destroys or inactivates the micro-organism so that it can no longer multiply. For DNA it does this by causing adjacent thymine bases to form a chemical bond thus creating a dimmer and if sufficient of these are
created, DNA cannot replicate. Some micro-organisms can repair themselves by absorbing UVA. In other cases UVC (and indeed UVA or UVB) can cause bond splitting in a molecule resulting in the creation of free radicals, which are often highly labile and which can react together to produce an inert end product. For purifying these effects are produced by wavelengths below 320 nm, with the optimum effect occurring at around 260 nm.the phenomenon whereby micro-organisms can be disfigured or destroyed is independent of host state (fluid or solid). Indeed with ph or temperature, the important feature of the action is that radiation can reach the organism; this means that a bacterium shadowed by another or by a particle will escape attack. Unlike other techniques, UVC photolysis rarely produces potentially dangerous by-products. RESULTS AND DISCUSSIONS Performance test against human cleaning Water consumption test
The results of the water consumption test are tabulated and a graph is plotted showing the variation of water consumption with the number of utensils washed in case of manual washing and commercial utensil sterilizer. The observations derived are When the load is less that is number of utensils washed is less customer utensil sterilizer consumes less or same amount of water as that of manual washing. As the load increases amount of water used by customer utensil sterilizer is more than that of manual washing. In case of manual washing the same water is used to soak many utensils. In case of manual washing only soap water washing is employed. This results in less consumption of water as the load increases. Time consumption test
The results of the time consumption test are tabulated and a graph is plotted showing the variation of time consumption with the number of utensils washed in case of manual washing and commercial utensil sterilizer. Observations In case of manual washing the time taken for washing is the function of number of utensils washed. In case of Commercial utensil sterilizer time taken is not a function of number of utensils washed; it remains constant that is 5 min. Time calculated in case of commercial utensil sterilizer consists of time taken for washing as well as sterilizing. The time taken for manual washing increases linearly because fatigue factor affects efficiency of human cleaning. SCOPE FOR FUTURE WORK To incorporate ultrasonic cleaning technology Ultrasonic cleaning is the rapid and complete removal of contaminants from objects by immersing them in a tank of liquid flooded with high frequency sounds waves. These nonaudible sound waves create a scrubbing brush action within the fluid. The process is brought about by high frequency electrical energy that is converted by a transducer into high frequency sound waves ultrasonic energy. Its ability to clean even the most tenacious substances from items derives from the core of the unit: the transducer. The cleaning power of a unit stems from the transducers performance. The ultrasonic energy enters the liquid within the tank and causes the rapid formation and collapse of minute bubbles: a phenomenon known as cavitations. The bubbles rapidly increase in size until they implode against the surface of the item immersed in the tank in an enormous energy release, which lifts contamination off the surface and innermost recesses of intricately shaped parts.