How to choose a fluid handling system for pumps in modern food processors, designers and operators and managers of these devices faces a variety of health-related responsibilities that go beyond the typical manufacture of industrial products. As consumers of the final product are public, product contamination must be avoided and corrosion is not tolerated. Cracks and dead spots in pumps and piping systems that allow fluid retention and bacterial growth are unacceptable.
In addition to the selection of food contact surfaces for material selection and processing, the food industry must also choose the piping and tank equipment used to deliver acidic and alkaline cleaning fluids for system maintenance, as well as the use of corrosion that meets the various environmental standards Sex chemicals for sewage treatment equipment.
Pumps required in food applications where the material of manufacture does not chemically react with the product or in any way affect the taste, color and other characteristics of the product. Design factors for non-food contact fluid equipment include reduced maintenance and downtime, higher throughput and lower costs, as well as many difficult-to-determine factors related to supplier knowledge and service.
One use causes another use
The interest in plastic pumps began more than 50 years ago when a Vanton flexible linear screw-rotor pump was manufactured to meet the stringent pump / cardiac requirements for heart / lung surgery. The unique but simple structure of this original pump restricts fluid access to only two basic components: a solid plastic pump body and a rough synthetic rubber molded liner. It addresses two major issues related to non-polluting treatment of human blood or blood. First, it avoids all the dangers of metal contamination because the contact material does not pollute the blood or react with it. Second, its gentle motion does not damage blood cells during blood delivery. Another reason why such a pump is accepted is its simple structure. It does not contain valves, seals, packing or gaskets. Its disassembly cleaning and reassembly simple and quick.
Since then, new areas have been opened up with the help of chemical manufacturers such as DuPont, Doyle, Atofina and other chemical companies. They are at the forefront of developing a wide range of thermoplastics for treating corrosive chemicals: acids, bases, salts, solvents and the like.
Moving forward
Pump designers incorporate these new materials into cost-efficiency pump designs to meet the needs of an expanding processing industry. Today there are about 150,000 flexible linear pumps of this type - with a total capacity of 40 GPM - for use in the United States and roughly double the number of pumps in Europe. In addition to the need to handle a wide range of sensitive and corrosive fluids at low flow rates to medium flow rates with these thermo-plastic rotary screw pumps, the higher delivery required for handling chemicals, food, pharmaceuticals and related processes and industries Flow, non-metallic pump requirements is the use of new structures. Pump manufacturers responded to this request.
Thermoplastic centrifugal pump designs are available in horizontal and vertical configurations for flow rates up to 1500 GPM, lift of up to 400 ft and continuous or discontinuous operation at 275 ° F or slightly above. They are available in ANSI-approved pump models and can be housed in solenoid-actuated sealless mechanisms and automatic starters. Vertical pumps have the ability to dry run, and have a unique segmented shaft structure that allows for a length of 50 ft. All of these types can be used in the food industry because of their design and construction without metal components in contact with the fluid.
typical application
Sticky mustard and vinegar
The flexible linear screw-rotor pump allows it to handle clear and 6000 SSU viscous fluids, slurries and even fluids with small particles. In this device, vinegar is stored at ground level and then pumped into a tank above the floor. Then it flows into the ingredient tank due to gravity and adds mustard seeds and salt to the ingredient tank. The mixing ingredients are discharged into a mixing / mixing tank and the resulting mustard product is pumped into a hopper and placed in a bottle on a moving conveyor belt.
The pump installed by August Barer & Sons requires a throughput of 10 GPM at a pressure of 50 PSI and a viscosity of 5000 SSU. Only two parts come into contact with corrosive fluids. They are all plastic. The life of a thicker polypropylene cylinder is unlimited as it does not react with food and its smooth interior also reduces wear. The synthetic rubber flexible liner also does not react with the food but buckling of the liner pulls away a portion of the product, especially if the fluid contains abrasive powders. A service report provided by the company states that such pumps for the treatment of vinegar require only a change of liner in the first 20 years of its operation. Although pumps that handle viscous mustard require regular and scheduled liner replacement, this work can be done in the field in minutes without the need for special tools.
Dairy processing and its environment
In the production of dairy products such as milk, butter, yogurt, ice cream, tofu, fruit juices and many confectionery, many of the processing of caustic chemicals used in washing equipment are in many ways similar to the treatment of these chemicals throughout the industry. It is also important to note that the discharge into the air or the contamination of the local water system or waste water system should comply with the requirements of the environmental code. These require that the structure and materials be carefully chosen to ensure that these pumps are resistant to the corrosive and abrasive nature of the fluid and that these fluids can be thoroughly discharged after use and that they do not contaminate the food they handle after cleaning is complete.
Tuscan Dairies is a larger dairy processor in the United States that requires daily cleaning after production. Tuscan's standard procedure requires washing the fluid handling system and disassembling, cleaning, and reinstalling the equipment used. This process is accelerated by the use of strong base and strong acid solutions as well as a variety of chemicals to neutralize waste streams before they flow into the wastewater system. Flexible linear pumps are well suited for delivering chemicals to tanks and draining them from these tanks. There are seven types of synthetic rubber materials that can be used for this type of liner, and four for the body of the pump.
A modern dairy company in Scotland faces a variety of problems in meeting local water agency requirements. These problems arise because of the dilute sulfuric acid injection in the wastewater treatment system to help coagulate waste milk / wastewater. This regulation of effluent pH and control requirements are very strict. Steill, a British craftsman, tackles the problem with the dairy:
To ensure complete resistance to aggressive chemicals used, all fluid-contacting pump components use homogeneous polypropylene because of the wide range of pH values ​​with which they will not chemically react.
For the treatment of water / milk and sulfuric acid, the pump is required to meet the Sump-Gard Vanton vertical centrifugal pump with a thermoplastics drain riser and stiffeners of the same material. The pump housing, housing cover and impeller are molded from pure polypropylene. Shen bearings include ceramic inner sleeve and Teflon or ceramic outer sleeve. Stainless steel shaft sleeve with the same material.
For treated effluents, the pump is required to meet the Sump-Gard Vanton vertical centrifugal pump, the pump housing, housing cover, flange and impeller are made of homogeneous polypropylene molded, The open area for the drive housings is large for easy maintenance and a retractable front bearing to minimize shaft overhang and distortion.