Saunders Diaphragm Valves

For the most part engineers have a good understanding of metallurgy used in aseptic processing. However, the critical importance of non-metallic components, such as the diaphragm, has previously tended to be underestimated.

Diaphragm and other non-metallic ‘wetted’ components are now becoming increasingly important to plant engineers in terms of standards compliance and product quality.

Customers have become aware of the complexities of elastomer utilisation in the total plant process system. Elastomers are a complex mix of ingredients chosen to provide the right properties for the function of the component and the intended application. Elastomer ingredients may include carbon black, fillers, process aids, activators, accelerators and curing agents, as well as the base polymer. All these ingredients can, to some extent, affect the properties of the elastomer in terms of resistance to and tolerance of temperature, abrasion and chemical attack.

The correct base polymer is the starting point for an elastomer. This is crucial in creating the desired physical properties, environmental and chemical attributes in the finished diaphragm. Depending on diaphragm material there can be up to 40 to 50 commercially available base polymers. It is very important, therefore, to select the right one to obtain the required diaphragm properties for any application.

The design, ingredients, manufacturing process and control all play a major part in ensuring the finished diaphragm provides optimum performance in the customers’ process. For acceptance within the Biopharmaceutical industry, all ingredients must be FDA and USP Class VI conforming, but this is only the beginning.

Over many years, the expertise of Crane ChemPharma & Energy’s Saunders® brand in polymer processes has continually progressed so that all diaphragm solutions are developed, processed and controlled in-house, from base polymer mixing through to reinforcing, curing, testing, packaging and shipping.

Today, customers are also demanding traceability and Saunders® has been instrumental in complying with the end user’s validation requirement by providing fully certified traceability for the range of FDA/USP-conforming Saunders® HC4 Diaphragms. It is mandatory that all diaphragms used in Life Science applications must be manufactured from FDA conforming materials.

Diaphragm materials such as Modified PTFE, EPDM and silicone rubbers have to conform to the FDA code of Federal Regulations (CFR) Chapter1, Title 21, Part 177 paragraph 1550 (Perfluorocarbons) and paragraph 2600 (Rubber Articles). A further pre-requisite for any diaphragm supplier is to provide not only FDA conformance but also USP Class V and VI certification, which includes a detailed series of tests to determine the biological response of elastomers and polymers used in medical applications. All certified diaphragms must meet the criteria in section ‘88’ Biological Reactivity Tests, In Vivo Plastic Classes I to VI.

Saunders® Unique Drivers
• 85 year old history and accumulated polymer expertise
• Front to back ownership of all elements of the manufacturing process (raw ingredient to finished product)
• Conformance to all international regulatory and test accreditations
• Life Science industry commitment

Ethylene Propylene Diene Monomers (EPDM) is the most commonly used elastomer in aseptic applications due to a number of inherent properties - excellent resistance to aqueous media, heat and ozone resistance, and high performance steam resistance. The Saunders® new ER Resilience EPDM has been specially formulated in-house to provide industry leading performance.

Landmark developments
1. First Modified Steam grade TFM

2. NEW Saunders ER Resilience EPDM Diaphragm
• Enhanced surface finish integrity to assist process purity (ASME BPE compliant)
• 30% improvement in compression set ratio versus typical EPDM to reduce need for re-torque and ensure seal to atmosphere
• Excellent chemical resistance to typical Biopharm process media
• Front to back technology ownership optimizes security & reliability

3. EX Endurance Diaphragm
• Outstanding high temperature performance and resistance to long term exposure at elevated temperatures (up to 175C constant steam)
• Ideal for steam distribution and supply, sterile barrier, and block-and-bleed applications
• Improved seal-to-atmosphere performance and reduced requirements for re-torqueing of fasteners after thermo cycling

4. Passivation Diaphragm
• Reduced cost and TCO (Total Cost of Ownership) benefits versus single use of PTFE diaphragm
• High visibility tag reduces risk of diaphragm not being replaced after passivation
• Interchangeable fixing with Saunders PTFE diaphragm range
• Materials suitable for use with citric acid and EDTA-based passivation chemicals and typical post passivation clean and rinse solutions

Tel: 01633 486 666

Published in Valve User Magazine Issue 45

Winter 2018 // Issue 47
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