EDUR is a valued partner in development and implementation of industrial cleaning processes with its centrifugal pumps
The EDUR centrifugal pumps have become key system components for leading cleaning plant manufacturers in order to transport the cleaning medium efficiently and reliably to surfaces and objects. Due to fulfilling complex, application-specific tasks in industrial cleaning processes, EDUR is a valued partner in development and implementation for years.
Differently used conveyed fluid and cleaning procedures require careful selection of all pump components in terms of design. The compatibility of the conveyed fluid with the pump materials and the realization of flow requirements are an additional special task. The different requirements for wet-mixed cleaning with high component volume or cleaning with solvents containing hydrocarbon or chlorinated hydrocarbon in batch or single part cleaning are in the centre of our pump selection. Typical, albeit adverse conveying conditions such as dry run, vacuum operation, particles coming through gaps in the flow rate or slurping mode are taken into consideration and considered, for example, by means of special sealing systems and especially adjusted impellers. Depending on the cleaning system and process conditions, close-coupled pumps, in-line pumps or torque-flow pumps from EDUR are used. EDUR multi-phase pumps are used for downstream recovery of substances used and for wastewater treatment.
The requirements of different cleaning systems for centrifugal pumps are versatile. Basically, processes with aqueous cleaners as well as processes with hydrocarbons and solvents are distinguished here. Another focus represent pre-treatment plants for colouring and powder coating.
Cleaning systems with aqueous cleaners
For low-alkaline and slightly acidic cleaners – e.g. in food processing – centrifugal pumps in low-alloy stainless steel are basically used. Cleaning-in-place capability is here often a precondition of the pump systems, however hygienic sealing systems are required and implemented.
In industrial cleaning of components, a large number of different alkaline and acidic cleaning media are used in practice. These are often not exactly known in advance and are also changed in the course of the operating time of the systems. Pumps of high-alloy stainless steel with single-acting mechanical seals as shaft seal and elastomers of Kalrez / polytetrafluorethylene (PTFE) have proved very well in practice. These higher quality elastomers are suitable here for all usual media and thus offer safety for a continuously reliable plant operation.
For plant drainage pumps, which have to convey more or less impurities depending on the relevant application, impellers with a large ball passage are selected so that solids do not block the pumps. Used are either torque-flow impellers or closed impellers with a small number of blades. The pumps mainly operate with simple mechanical seals. Modifications also enable fulfilment of special requirements such as gas conveyance, e.g. with outgassing and residual discharge. Double mechanical seals, e.g. in tandem version with oil bath, allow “slurping mode” and short-time dry run.
If very fine solids have to be expected in the cleaning medium (e.g. due to polishing pastes), or very contaminated parts are cleaned (e.g. during reconditioning of old parts), it has to be reckoned with premature wear and tear of a simple mechanical seal. Therefore, centrifugal pumps are designed with a double mechanical seal in back-to-back arrangement. A suitable barrier pressure system ensures fault-free operation.
Cleaning systems with hydrocarbons and solvents
In metal surface cleaning, hydrocarbon compounds were often used in the past. Solvents such as perchlorethylene and trichloroethylene are today less commonly used. Because of explosion protection, hydrocarbon plants are operated under vacuum. The tempered medium is thus close to its boiling point. Also under these conditions, the pumps must fulfil their tasks.
For this, the centrifugal pumps are equipped with special suction impellers exhibiting very good flow characteristics and ensuring high process safety also under these conditions. A lot of these pumps are tailored to the customer's processes: These “special pumps” have a double mechanical seal (tandem or back-to-back). On the product side, the special mechanical seal reliably seals, also in case of system standstill under vacuum.
Depending on the requirement, the pumps can be delivered in grey cast iron version and also in stainless steel.
Pre-treatment plants for colouring and powder coating
With many pre-treatment plants, partly very acidic media are used. Furthermore, it often comes to precipitation of solids. As a result, an exact pump design is indispensable by means of the product data sheets in order to determine and implement the right sealing concept above all. Nowadays, high-alloy stainless steel pumps are almost exclusively delivered for these applications or low-alloy ones for flushing processes.
With bathes for degreasing, iron-phosphating, stain and passivation, high-alloy stainless steel pumps with single special shaft seals fulfil a large number of imposed requirements.
With acidic stain, higher quality stainless steel pumps in cast iron construction are used with double shaft seals which have sufficient wear and tear reserves.
In case of processes with very strong solid precipitation - e.g. zinc-phosphating - sealless container submersible pumps made of high-alloy stainless steel are mainly delivered nowadays.
Here, heavy deposits would limit the service life of shaft seals.
Basically, EDUR is prepared for all special requirements of industrial cleaning processes.
Their application specialists provide reliable concepts during joint design with the customer.
Source & Pictures: EDUR Pumpenfabrik