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Special Centrifugal Pumps Learn How Sturdy Horizontal Pump Meets High-Performance Material

| Author / Editor: Annette van Dorp / Dr. Jörg Kempf

The special challenges when a pump is used include the pumping of media which are simultaneously hot, abrasive and corrosive. A producer of fertilizers needed to take action urgently; the pumps used up to that time could not cope with the process medium: They stopped working after an extremely short period of use. Bungartz, the manufacturer of special centrifugal pumps, developed an intelligent combination for that scenario.

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Wear plates made of SiC protect the casing and also extend the service life of the impeller.
Wear plates made of SiC protect the casing and also extend the service life of the impeller.
(Picture: Bungartz)

The first success message came in September 2009. The conversion of the pump five months ago went off successfully. “We were using different pumps. The best of them only lasted four weeks,” is how the plant manager responsible for the system at the internationally renowned company described the situation. “Since the 30th of April the replaced pump has been running without a single breakdown, no abnormalities, no problems,” he goes on.

Pumps, compressors and fittings at Achema 2015
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For Bungartz, which has distinguished itself worldwide as a reliable problem-solver, this result is a further success. The initial situation on site was extremely unfavorable. The previous pump hardly ran for four weeks without incident. Not only had this normal-priming centrifugal pump struggled to cope with the extreme pumping medium, with which it had considerable problems.

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The manufacturing company had already tried various types of pump. None of the pumps that had been tried so far was able to cope with the difficult pumping medium. The consequence of this before the conversion was that there were repeated prolonged and unplanned downtimes, which also resulted in major repair costs. A solution was urgently required. The aim: to increase the period of use by replacing the entire pump and optimizing the costs over the long term.

Pumping Media with High Proportion of Solid Matter

The specialists from Bungartz took over the case. They carried out a precise analysis of the cause of the failures. “The pump and process medium did not match,” is how Hans-Wilhelm Möllmann briefly summarizes the situation. The Head of the Research & Development Division knows these damage patterns only too well. Here, the properties of the process medium, which is a mixture of nitric acid, phosphoric acid and abrasive sand, systematically destroys the material used and brings the pump to a standstill.

This contrasts with the sturdy M-MOR type pump made by Bungartz. It is equipped with a hydrodynamic seal without sealing or flushing liquid. Even in continuous operation, there is no risk of leakage. Despite their high performance, the pumps of the series MOS/UMOS are simple to operate. They are not susceptible to operator error, so no highly specialized technicians are required on site.

Good results are obtained even by the pump made of duplex stainless steel with a semi-open impeller and a casing which is equipped with wear plates made from the same high-performance material SiC in the front and rear section. Nevertheless, the team was not prepared to settle for what had already been achieved. In the next step, not only the wear plates are made of SiC, but also the impeller. At the spiral start of the casing, an insert made of the high-performance material zircon oxide provides additional stability.

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