Diaphragm valves: CIP

Sometimes the solution to a problem comes by turning it on its head. Alcon, a member of the Nestlé group, is a leading eye care company with a plant in northern Belgium. It manufactures and markets products especially formulated for ophthalmology, including vision care products and surgery sets.

The brief when Alcon needed to redevelop its facilities included upgrading and reconfiguring its manufacturing and clean processing areas to reduce the amount of process piping, and to comply with today's prevailing production standards. Dirk De Rudder, senior project engineer at Alcon's facility at Puurs, near Antwerp, Belgium, believed that they could increase efficiency in the CIP cycle by redefining the valve configurations to reflect their specific processes. The company had undertaken a feasibility study on designing process vessels and integrating standard HC4 tank bottom valves into the top dome. Alcon then took the findings to CPFT to develop the solution. David Birch, CPFT's HC4 product manager based at the company's production facility in Cwmbran in Wales, says Alcon Belgium wanted to develop a prototype tank top valve to enhance the renovation programme of its process vessels for sterile production. In addition, to transform the overall aesthetic feel of the processing system, it specified all topworks, including actuators and switchboxes, would be manufactured from stainless steel.

Innovative unit "Alcon's demand for a stainless steel actuator and switchbox combination mirrors its desire to present an upgraded cleanliness concept," he adds. "It would combine the functional aspect of improved material quality with the aesthetical aspect of a harmonised processing system." The specifications for the modified Saunders HC4 devices were innovative as the new unit would greatly speed up regular cleaning cycles by eliminating the need for additional CIP systems to clean the valve's diaphragm. Having accepted the challenge, CPFT began the design and development work. Remodelling options were created using 3D CAD software, which incorporates a Virtual Reality Modelling Language (VRML) tool. Technicians and designers from both Alcon and CPFT decided it would be wise to base the remodelling upon the standard HC4 valve design. This would allow the use of existing fabrication tools and preserve the desired interchangeability of the new units. "We've always been satisfied with the efficiency and quality of Saunders HC4 aseptic valve design," adds De Rudder. "It was natural, therefore, to avoid remodelling options that would require modifications to the diaphragm's fitting arrangements. The decision would not only ensure a fast turnaround of the prototype but also keep development costs to a minimum." CPFT remodelled the Saunders HC4 tank bottom valve with two mounting options. The first could be welded directly into the process vessel's top dome surface and the second option used a tri-clamp type fitting, combined with a flush mounting assembly, allowing the valve to be removed easily. The counterpart of the tri-clamp flange could be integrated into the tank valve body and machined to accept an inducer, designed to train incoming fluid against the vessel's interior wall instead of directly into the product blend to prevent foaming. Alcon stipulated the inducer could not be incorporated as a fixed element of the vessel's overall construction, as doing so would dramatically hinder polishing the inside vessel surface. In addition, the company placed a mandatory rider limiting the overall weight of the valve in order to prevent undue stress to the piping system. "Of course, we knew we'd have a problem with drainability if we attempted to fit standard diaphragm valves in this orientation," continues Birch. "So we considered a number of further modifications such as diminishing the width of the metal weir that supports the diaphragm itself and were able to achieve acceptable performance, even with a very shallow-curved vessel dome and the fact that the sealing surface had become smaller as a result."

Minimum downtime In effect, the valve has become an integral part of the compounding vessel rather than a mounted accessory, no matter which of the two fitting options is employed. The final design provides an optimum basis for maintaining minimum potential process downtime resulting from Alcon's CIP regimes. Having remodelled the standard Saunders HC4 valve, CPFT fitted the unit with a silicon diaphragm and undertook extensive trialling of the prototype unit on site in Puurs. It was then fitted to one of Alcon's new process vessels and subjected to 7bar pressure. The 'bottom-to-top' valve development concept passed all integrity targets. Alcon Belgium is the first pharmaceutical processor to use the 'one-size-fits-all' stainless steel actuator/switchbox combination in significant numbers. In excess of 200 units are currently incorporated into the company's compounding system. "Alcon has always placed a great emphasis on the quality of its products," continues De Rudder. "A high degree of cleanliness, in terms of modelling our process environment and the design of our production equipment, is an ongoing evolution in this company. We have benefited from availing ourselves of the proven flexibility of CPFT's approach to meeting our requirements." This project is the latest in a series of collaborations that have seen Alcon and Saunders working jointly for the past 15 years. The result is a successful solution to the challenge of integrating Saunders HC4 tank bottom diaphragm valves into the domes of pressure vessels for sterile production, which has resulted in reduced CIP cycle times.