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.

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.

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.

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.