Erosion and clogging in china clay pumps


A customer specialized in the manufacture of pumps for china clay was suffering from short life time of the shaft seals, down to a few weeks. End users were not happy with the situation suffering from both down time and costs.

After an analysis of the application, the processed media and the equipment an especially designed cartridge seal was presented having a focus to manage current erosion as well as clogging problems. The design was well received bringing up the mechanical seal life time to end-user expectation.

Mechanical seals being clogged up with bentonite residues


End users was facing issues with the mechanical seals being clogged up with bentonite residues being dissolved in the water being pumped. A Roplan design using a rubber protective guard with a maintained double balancing ensures the proper operation of the mechanical seal under all operating conditions.

Critical pump failures solved with minimum downtime

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One of the pump producer’s global customers was experiencing pump failures at their facility in China. The situation was critical and the end user demanded a solution ASAP.

Roplan Ltd worked with the pump producers design engineering team in England while Roplan Ningbo worked with their sales and application engineering team in China. Due to different process media and the critical need for solution Roplan Ltd designed and provided 3 sets of samples.

The applications at the end user’s facility were demanding and unique, it was vital to gather information from the failures via analysing the failed pumps and seals before they were disassembled. Of course, the end user could not let this facility sit idle waiting for the pumps to be serviced. To address this, spare pumps were supplied with the trial seals installed along with seals to service existing pumps.

Roplan Ningbo met with the customer at the end-user’s facility to witness the installation of the new pumps, evaluate the failed pumps, collect application data train the pump builders team to install the new design seals and oversee the installation.

The initial trials showed improvement but did not reach the end users expectation. When there was an incident Roplan engineers were in the end-user’s facility within a matter of hours of analyse the failures, gather additional information, discuss potential application problems and install replacement seals to keep the plant running. They then communicated with Roplan Ltd. Based on this design modifications were made and additional samples were installed. The 2nd trial did reach the end users expectation and they plan to standardize one solution throughout their facility.

By utilizing Roplan’s expertise and global support the pump builder was able increase the capabilities of its team in China while satisfying and strengthen the relationship with a key customer.

Twin screw pumps (TSP) modified to meet EHEDG test


Twin screw pumps (TSP) are a challenge due to low speed pattern around the shaft seals. This in turn puts high requirements on shaft seal design and commonly moulded elastomers are required to ensure clean in place (CIP) procedures are successful. This is usually verified applying the EHEDG (European Hygienic Equipment Design Group) test procedure. The use of moulded elastomers are generally accepted however puts limitations on qualities available for use.

Having the incentive to only use standard sized O-rings within the design, a working solution being able to successfully pass the EHEDG test protocol was designed. The customer can now apply virtually any elastomer quality being requested by the end-users without being limited to what is available as moulded parts.

Solving Electro-chemical corrosion in high-speed equipment


Water for injection (WFI) is commonly used in the pharmaceutical process industry, however the very low conductivity of the media can cause electro-chemical corrosion of the Silicon Carbide when used in centrifugal pumps and other high-speed equipment. As a result, end-users were suffering stochastic life time from the mechanical seals applied.

From extensive testing in the Roplan test lab with different Silicon Carbide qualities in WFI, a best performing Silicon Carbide quality could be verified. Stochastic life-time has now been reduced to a marginal problem.