Products and Capabilities

Diaphragm Seals


Molded diaphragm seals often provide the best possible solution to a sealing problem… and frequently they are the only solution.  They are widely used wherever accurate, reliable response to hydraulic or pneumatic pressure changes is needed. 

RPP Corporation specializes in custom, fabric reinforced diaphragm seals.  Our experienced engineering team works with customers and material suppliers to design highly engineered, high performing, cost effective diaphragms that exceed life cycle requirements.   

RPP diaphragms are routinely used in such diverse applications as process control equipment, water management, precision medical equipment and in the transportation industry.  Since they can be custom designed quickly and inexpensively to meet a wide variety of conditions and requirements, RPP diaphragms frequently represent invaluable solutions to equipment design problems.






Large Diaphragms


RPP is an expert at molding very large diaphragm seals.  With some of the largest compression molding presses in the industry, RPP can manufacture diaphragms up to 46 inches / 1.168 meters in diameter and up to 15 inches / 381 mm tall (assuming a 1:1 bore to height ratio).  Our raw material preparation equipment, large format compression molding presses and our knowledge of elastomers and fabrics give RPP the ability to manufacture large, high quality, fabric reinforced, single or double coated diaphragms that very few companies have the capability to provide.  Additionally, our customers obtain a customized elastomer/fabric combination that fits their targeted requirements.  Our largest diaphragms are generally used in control valves for the oil & gas, utility and nuclear industries.


Rubber Bonding to Metal, Teflon, Plastic & Other Elastomers


RPP has developed special material preparation, molding and post curing processes for bonding elastomer to metal, Teflon and plastic in diaphragm and non-diaphragm applications.  Typical applications include the bonding of aluminum or stainless steel valve seats, rings and stems to elastomer diaphragms or to Teflon coated elastomer diaphragms.  This component integration often improves often improves the overall product design and performance, and can reduce labor costs as well as material planning and inventory requirements. Our knowledge of materials also enables us to bond dissimilar elastomers to each other or on alternate sides of a diaphragm. 





Design Assistance


RPP’s technical team has decades of experience assisting customers with custom product designs focused on product performance, quality, manufacturability and cost.  From customer requirements, to Diaphragm Design and Design Validation, RPP is there to help customers develop the best products while avoiding costly mistakes.  RPP continually reviews mold design techniques and raw material availability to ensure we take advantage of technological advancements and new material capabilities.  We look forward to helping companies with their toughest problems and regularly “come to the rescue” of those who may have originally chosen a different sealing solution.   





Diaphragm Materials


Elastomer - The elastomer layer(s) of a diaphragm  must be extremely thin (for maximum flexibility), very tough (to withstand repeated flexing over a long lifetime), able to handle anticipated operating temperatures, and resistant to whatever chemicals, fluids or gases it may be contacting.

Over 45 standard and custom elastomers such as Nitrile, EPDM, Viton, AFLAS, HNBR are available, one of which usually meets the application requirements. RPP material specialists also work closely with our synthetic rubber compounders to develop custom materials to meet specific customer needs. RPP’s proprietary EPDM elastomer comes in three colors, white, purple and standard black. Its high degree of inertness and robust physical properties makes it ideal for harsh water environments with high chloromine & chlorine levels. A new low cost Type A FKM is a popular choice for the toughest chemical applications.  Additionally, because RPP manufactures its own coated fabrics, diaphragms can be produced with almost any combination of elastomers and fabrics.  RPP can even produce coated fabrics with different elastomers on each side of the fabric. 

Fabric- The fabric used in molded diaphragms is a highly engineered industrial textile employing a specially developed weavepattern with a unique property. In one direction, it stretches easily, allowing for the radial flexing of the diaphragm convolution. In the other (axial) direction, it provides high resistance to elongation and furnishes the tensile strength that enables the seal to withstand high differential pressures and transmit force to the piston head. RPP has over 20 standard and custom varieties of fabric designed to meet specific operating conditions including Polyester, Nylon and high temperature / high strength fabrics such as Nomex and Vectran. Special, low cost knit versions are also available for high volume and low hysteresis (for more sensitive applications).




Tool Design & Fabrication


RPP designs and fabricates molds and tools up to 30 inches in diameter in its fully equipped machine shop.  RPP utilizes nearby, outside shops to produce larger molds.  This combination of internal and local resources enables RPP to provide short lead times for your critical applications.  Because we have control of the process from design concept through mold fabrication, we get it right the first time.  Our in-house capability also facilitates the efficient and timely completion of mold maintenance and modification requirements.  This is just one of the valuable resources our creative technical team uses to provide customer solutions quickly and in a cost effective manner.





Nuclear, NSF & FDA Products


Producing product to tight tolerances and specifications and in accordance with 10CFR50 Appendix B, RPP is a leading supplier of diaphragms to the nuclear power industry.  RPP’s 10 CFR50 Appendix B Certified Material Option is a comprehensive program of testing and documented processes related to the tested physical characteristics of commercial grade material used in “safety related applications”.  With materials formulated to meet CFR21, RPP manufactures NSF and FDA compliant diaphragms suitable for food service and medical applications such as pumps, metering systems and life support apparatus.