The customer was requesting a mechanical seal having the involved materials to comply with WRAS but with a maintained cost structure as present solution used. Working together with our suppliers we were able to present a solution that was meeting both cost and compliance requirements.
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.