Bombas centrífugas de acionamento por ímã de plástico
Processos de acabamento e revestimento de metal são reconhecidos como estando entre as aplicações mais desafiadoras para bombas. Isso geralmente ocorre como resultado do ambiente no qual as bombas estão operando, juntamente com a ampla gama de fluidos agressivos usados em muitos desses processos de tratamento e acabamento de superfície. A linha de bombas centrífugas de acionamento por ímã de plástico da Thompson, disponíveis através da MICHAEL SMITH ENGINEERS, tem sido usada com sucesso em algumas das mais exigentes aplicações de acabamento de metal.
Um exemplo interessante é a Wright McGill, fabricante da marca Eagle Claw Fishing Tackle, uma empresa localizada no Colorado que usa bombas da série Finish Thompson DB. A empresa produz milhões de anzóis de alta qualidade a cada ano em uma infinidade de estilos e cores, o que exige uma gama incrivelmente eficiente de processos de acabamento de metal de precisão. Esses processos incluem níquel, níquel eletrolítico (EN), estanho, latão, zinco, bronze e até chapeamento de ouro. Os ganchos são fabricados em tantas cores porque as cores específicas foram consideradas atraentes para certas espécies de peixes. Além do revestimento, os seus processos de acabamento de metal incluem também a lavagem, o tratamento térmico e a aplicação de vários revestimentos de tipo de tinta.
In 2005, Finish Thompson were completing the design of their latest magnetic drive pump, the DB Series, which featured engineered plastics and other specialised materials to ensure optimum corrosion resistance.
As well as using these materials they benefitted from the latest engineering technology including computational fluid dynamics, finite element analysis and custom magnetic design software.
To complete the development and testing process Finish Thompson needed an appropriately demanding test site and the Eagle Claw manufacturing site was happy to oblige. One of the processes involved concentrated nitric acid, used as a stripping agent to remove built-up plating materials on barrels and other items used in their plating processes. Nitric is an extremely aggressive highly oxidizing acid capable of dissolving most metals and has a severe effect on many other materials. Eventually, the nitric acid became saturated with the various plating products removed during the stripping process and engineers started to look at ways of reducing the use of nitric acid. This led to the installation of the DB Series pump on a trail basis within a filtration system which was designed to recycle the nitric acid.
A DB test pump was manufactured from extremely corrosion resistant materials including precision moulded carbon fibre filled PVDF, PTFE bushing, high purity ceramic and powerful neodymium drive magnets encapsulated in pure PVDF. It was then installed in the nitric acid recycling system, a truly challenging application. Once installed on the filtration system it was used to circulate approximately 680 litres of nitric acid through a series of filters with each filter removing progressively smaller particles. The goal was to re-circulate the tank about three times per hour until the nitric acid was clean enough for reuse. The pump was in regular operation for six months while the effectiveness of the filtration process was evaluated. Due to the excellent performance and reliability of the pump in that test, Wright McGill continues to use Finish Thompson magnetic drive pumps for handling corrosive and hazardous fluids in applications throughout its facility.
As a result of the non-metallic materials used for both the housing and all the key wetted components, DB pumps are ideal for transferring corrosive liquids in chemical manufacturing, metal plating, surface treatment, wastewater treatment, electronics manufacture or wherever hazardous liquids need to be pumped safely.
They are available in a close-coupled design configuration for optimum magnet alignment and provide extended dry-running capability when specified with a carbon bushing and are therefore protected from system upsets.
Other features and benefits include; high operating efficiency resulting in lower energy consumption, improved hydraulic coverage for both 50 and 60 Hz operation. They have evenly spaced impeller trims enabling duty points to be precisely met and a two-piece impeller design which allows the impeller or inner drive magnet to be individually replaced. Also, the DB Series pumps offer high working pressure capability which means fluids with a high specific gravity can be easily pumped without the need for impeller trimming.
The pumps are designed for either horizontal or vertical installation (vertical when equipped with an IEC motor), they have a maximum operating temperature of 180°F (82°C) for the polypropylene model and 220°F (104°C) for the PVDF option.