Flowguard’s Transfer Series was designed with the food, beverage and pharmaceutical industries in mind. It is a double elastomer bladder design with a fluid between the membranes which transfers the hydraulic pulsation from the process fluid to the upper membrane that holds the precharge gas. These vessels are ideal for hygienic services that require clean-in-place (CIP) components. In tests carried out by Campden & Chorleywood Food Research Association to the EHEDG protocol, it was found to clean better than the reference pipe.
The use of two membranes which are hydraulically connected with a transfer fluid overcomes the problems of crevices and product stagnation that are inherent in most other dampener designs. To ensure efficient cleaning during the CIP cycle, it utilizes a true flow through design with the product wetted lower shell being crevice free and having no small corners or “dead” areas.
The dampener shell is most often constructed of 316/316L Stainless Steel but other material options may be specified. Mechanical polishing, electro-polishing and bead blasting may be requested for normally wetted surfaces.
The lower (process wetted) bladder is normally specified as a food grade elastomer that is compatible with the process conditions as well as the cleaning regime and the transfer fluid. The upper (gas precharged) bladder is normally a standard grade elastomer that is compatible with the transfer fluid at the process and cleaning temperatures.
The transfer fluid is selected in conjunction with the client and should be compatible with the steel shell and elastomer bladders as well as the process fluid in case the lower bladder fails. There should also be a substantial margin between its boiling point and the maximum system temperature. Commonly used liquids include sterile water, food grade glycerin, vegetable oil, mineral oil and alcohol. In cases where a membrane failure detector is required, it is also an additional requirement to have a significant difference in conductivity between the process and transfer fluids.
The process connections are normally sized to match the adjacent piping to avoid constriction of flow and to maintain fluid velocity. The connection type is specified to suit the customers requirements, but commonly used connections include: NPT threaded, ANSI flanges, Tri-Clamp® Fittings, Anchor Fluid Power Flanges and Grayloc® Connector.
Other specialized features available include hot water/cold water jackets, mounting brackets and a membrane failure detection device (conductivity probe).