Selection of materials and structures of pumps in

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Selection of pump materials and structures in food machinery

how to select the fluid treatment system of pumps in modern food processing devices? Designers and operators and managers of these devices face various health-related problems, which have gone beyond the scope of normal industrial product manufacturing. As the consumers of the final products are the public, product pollution must be avoided, corrosion is not allowed, and cracks and dead spots in the pump and pipeline system that can cause fluid retention and bacterial breeding are unacceptable

in addition to material selection and food contact surface selection during processing, the food industry must also select pipeline and storage tank equipment used to transport acidic and alkaline cleaning fluids during system maintenance, as well as equipment for sewage treatment using corrosive chemicals that meet various environmental standards

for pumps required in food applications, the manufacturing materials shall not react with the product or affect the taste, color and other characteristics of the product in any way. The design factors of non food contact fluid equipment include reducing maintenance and shutdown time, increasing production and reducing costs, as well as many uncertain factors related to supplier knowledge and services

one use causes another

people's interest in plastic pumps began more than 50 years ago, when a vanton flexible linear screw rotary pump was manufactured to meet the strict requirements for pumps in heart/lung surgery. The unique but simple structure of this original pump limits the fluid to only two basic components: the solid plastic pump body and the rough synthetic rubber molded lining. It solves the two main problems related to non polluting treatment of human blood or affecting blood. First of all, it avoids all the risks of metal contamination, because the contact material does not pollute or react chemically with blood. Secondly, its gentle movement does not damage blood cells in the process of blood transmission. Another reason why this kind of pump is accepted is its simple structure. It does not contain valves, seals, packing, or gaskets. Its disassembly, cleaning and reassembly are simple and fast

since then, with the help of chemical material manufacturers such as DuPont, Doyle, atofina and other chemical companies, new fields have been opened up. They are at the forefront of the development of a wide range of thermoplastic materials for the treatment of corrosive chemicals: acids, alkalis, salts, solvents, etc

advanced technology

the designers of pumps combine these new materials into the design of cost-effective pumps to meet the needs of the expanding processing industry. Today, about 150000 of these flexible line pumps - with a total capacity of 40gpm - are in use in the United States, and about twice the number in Europe. In addition to the need to use these thermoplastic rotary screw pumps to handle a wide range of sensitive and corrosive fluids at low to medium flow rates, in order to handle the higher delivery flow required by chemicals, food, drugs and related processes and industrial enterprises, the requirement for non-metallic pumps is to adopt new structures. Pump manufacturers responded to this request

currently available forms of thermoplastic centrifugal pump design are horizontal and vertical structures, which can be used for flow up to 1500gpm, lift up to 400ft, and can be used continuously or intermittently when the temperature is 275 ° f or slightly higher. They can be arranged in the model conforming to ANSI process pump standard, and can be arranged in the electromagnetic drive sealless mechanism and automatic starting device. The vertical pump is capable of dry operation and has a unique segmented shaft structure with an allowable length of 50ft. All these types can be used in the food industry because they are designed and constructed so that no metal components come into contact with the fluid

typical application

viscous this initiative aims to improve transparency and governance mustard and clear vinegar

flexible linear screw rotary pump allows it to handle clear and 6000ssu viscous fluids, slurries and even fluids with small particles. In this device, clear vinegar is stored at ground level and pumped into a tank above the floor. Then it flows into the batching tank by gravity, and mustard seeds and salt are added to the batching tank. These ingredients are discharged into a mixing/mixing tank, and the mustard product is pumped into a hopper and loaded into bottles on the moving conveyor belt

august barer & Sons' installed pumps are required to handle a flow of 10gpm at a pressure of 50psi and a viscosity of 5000ssu. Only two components are exposed to corrosive fluids. They are all plastic. The service life of the thicker polypropylene pump body is infinite because it does not react with food and its smooth interior also reduces wear. The flexible synthetic rubber lining also does not react with food, but the wrinkle of the lining will remove part of the product, especially when the fluid contains abrasive powder. According to a service report provided by the company, the lining of this kind of pump that has achieved 330wh/kg clear vinegar energy density only needs to be replaced once in its first 20 years of operation. Although pumps handling viscous mustard require regular and scheduled lining replacement, this work can be completed in a few minutes on site without the need for special tools

dairy processing and its environment

in the production of dairy products such as milk, cream, yogurt, ice cream, tofu, fruit juice and many sweets, the treatment of many corrosive chemicals used in washing equipment is similar to the treatment of these chemicals in the whole industry in many ways. It is also important to note that the pollutants discharged into the air or in the local water system or wastewater system should meet the requirements of environmental regulations. These require that the structure and manufacturing materials must be carefully selected to ensure that these pumps can resist the corrosion and abrasion characteristics of the fluid, that these fluids can be completely discharged after use, and that the food they handle will not be polluted after the cleaning work

tuscan dairies is a large regional dairy processor in the United States, which requires cleaning after daily production. Tuscan's standard procedures require that the fluid treatment system be washed and the equipment used be disassembled, cleaned, and reinstalled. This process is accelerated by the use of strong alkali and acid solutions and various chemicals to neutralize the waste liquid before it flows into the waste water system. Flexible line pumps are ideal for transporting various chemicals to and from storage tanks. There are 7 kinds of synthetic rubber materials that can be used for this lining and 4 kinds of materials that can be used for the pump body

a modern dairy plant in Scotland faces various problems in meeting the requirements of local water authorities. So far, these problems have been caused by the injection of dilute sulfuric acid into the wastewater treatment system to help coagulate the waste milk/wastewater. This is very strict for the adjustment and control of pH value of waste liquid. Steill, a British process design company, solves the problems of the dairy factory in this way:

■ in order to ensure the complete resistance to the corrosivity of the chemicals used, all pump components in contact with the fluid use homogeneous polypropylene, because the pH value range with which there is no chemical reaction is very large

■ for the treatment of water/milk and sulfuric acid, it is required that the pump can meet the requirements of vanton vertical centrifugal pump dump Gard, which has a hot plastic drainage riser and a reinforcing strip of the same material. The pump housing, housing cover and impeller are molded from pure polypropylene. Countersunk bearings include ceramic inner sleeves and Teflon or ceramic outer sleeves. The sleeve of stainless steel shaft is made of the same material

■ for the treated waste liquid, the requirements for the pump are to meet the requirements of the vanton vertical centrifugal pump pump pump, whose shell, shell cover, flange and impeller are molded from homogeneous polypropylene. The open sealing area of the drive bearing seat is large to simplify maintenance, and there is a retractable front bearing to minimize the suspension and deformation of the shaft. (end)

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