Selecting rubber parts for water applications

Look beyond the products, says Jefferson Rubber Works, to companies that engineer custom-molded rubber solutions, and constantly tests, adjusts and refines its processes and materials to meet the latest specifications.

Dave Pentland President Jefferson Rubber

Look beyond the products, says Jefferson Rubber Works, to companies that engineer custom-molded rubber solutions, and constantly tests, adjusts and refines its processes and materials to meet the latest specifications.

Dave Pentland

Depending on the particular segment of the water and hydronics industry -- the production of potable drinking water systems or the treatment of wastewater -- a number of different essential variables should be considered when selecting rubber components for equipment. These rubber components can include everything from manhole connector boots and pipe seals, to diffuser membranes and well and expansion tank diaphragms.

In the potable water industry, a principle driving factor that affects rubber part selection is the need to keep water safe and clean. And in the wastewater treatment arena, key considerations include: will the rubber stand up over time to a range of caustic materials and harsh conditions? This article will discuss the most important variables in each end of the water/hydronics industry spectrum, setting some basic guidelines that will help you select the right rubber parts for your application.

Potable water is not what it used to be, and that is good. Stringent standards in place today are designed to ensure drinking water is purer, cleaner and safer than it has ever been before. This means that all parts and materials that come into contact with this water must meet high environmental standards, including standards set by organizations including NSF International and Underwriters Laboratory in the United States, Water Regulations Advisory Scheme (WRAS) in England, Attestation de Conformité Sanitaire (ACS) in France, and other governing bodies throughout the world.

NSF Standard 61 is centrally important to part procurement for the hydronics industry, as it is the testing protocol that measures and limits the amount of lead and other contaminants that a device may contribute to drinking water. Part of the Safe Drinking Water Act, NSF 61 applies to anything that supplies drinking water, including kitchen faucets, bar faucets, water coolers, ice cube maker, and of course, municipal drinking water equipment.

Dave Pentland President Jefferson Rubber
Dave Pentland, president of Jefferson Rubber Works, Inc.

The effect of many standards, such as NSF 61, in terms of rubber part procurement is that it is essential for companies to work with a rubber manufacturer that is constantly testing, adjusting and refining its processes and materials to meet the latest specifications. Custom molded rubber solutions, as opposed to off-the-shelf rubber products, can meet specific requirements of current environmental standards. The company Jefferson Rubber Works, Inc. (JRW), engineers its rubber parts to address industry changes. The company continually adjusts its cure systems, tweak formulations, make changes to molding processes, and works to virtually eliminate any residual material in drinking water.

For example, sparked by France’s ACS’s new tighter odor/taste restrictions, JRW recently initiated a new series of intense tests in which its rubber materials spend days soaking in water. These new tests greatly exaggerate any potential real-world conditions, but in testing the water after thorough soaking, the tests virtually eliminate any concerns customers may have about JRW products effect on the taste or smell of their drinking water.

As with drinking water applications, a rubber manufacturer’s ability to be flexible and custom-tailor compounds is an essential ingredient in that part provider’s make-up. One compound definitely does not fit all, when you’re dealing with a potential wide range of corrosive chemicals and climatic conditions.

For starters, different materials are better for certain applications: Neoprene is well-suited for an oil environment; silicone can stand up to extreme heat and cold; and EPDM is the right starting point for a typical water and sunshine environment.

Sealing Boots

But in many cases, that is just stage one of the selection process. Often an application calls for a custom engineered and molded solution. In some cases, engineers should be involved from the initiation of a project. For example, a JRW aeration equipment customer needed a newly formulated wastewater diaphragm, as their existing diaphragms were shrinking over time. After conducting an extensive analysis, JRW engineers determined that an excessive amount of chlorine content in the water was attacking the rubber compound and creating the gradual distortion. The engineers reformulated the plasticizer, reducing its quantity while maintaining the material’s plasticity.

Not every rubber part supplier has engineers at the ready, or even the equipment to quickly and cost-effectively manufacture a range of custom solutions. When considering a solution provider for hydronics applications, look beyond the products. Does the company use injection molding equipment that produces small and large parts? Does it operate machines from 100 tons to 800 tons? Can it produce these parts at a high volume to provide the greatest efficiency, repeatability, and value? Also, is the company working with the most advance rubber technologies, as opposed to outdated compression and transfer molding methods? And does the company have a team of experienced engineers on staff to research, test, design and formulate advanced rubber technologies?

Finally, rubber parts should last. Look for a company that conducts rapid cycle testing to simulate real-world use over the life of a product or system. Look beneath the surface and examine the manufacturer’s ability to engineer, design and mold a solution that meets the specific unique needs of an application.

Author’s Note

Dave Pentland is the president of Jefferson Rubber Works, Inc., and is based in Worcester, Massachusetts, USA. Website:

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