Because they’re better than packing nuts. That’s the shortest and simplest answer to the question we often get of why we use double stem seals in our ProPress valves.
Double stem seals are superior to packing nuts in durability, longevity and leak prevention, and Viega only engineers and manufactures the most reliable products.
Packing nut designs consist of packed Teflon that sits around the stem between the handle and ball of the valve. As the Teflon shifts or deteriorates, a leak path will form, requiring someone to tighten the packing nut. This creates additional hours for installation as well as continued maintenance.
This is an example of a valve with a packing nut:
Unlike packing nuts, which are used in many valves in the industry, the EPDM seals used in Viega’s valves will not deteriorate and leak. The double seals also eliminate the need to constantly tighten packing nuts, saving numerous hours on the front-end and back-end of installation. As many who’ve dealt with leaky valves can attest, a valve can only be tightened so many times before the packing no longer can hold the seal. At this point, the valve must be replaced.
Double EPDM seals between the handle and ball are standard on Viega's 2-piece valves. They are installed with a static seal, eliminating any wear and tear issues. EPDM is a synthetic, cured, all-purpose elastomer with excellent resistance to chemicals and other harsh environmental conditions. With operating temperatures from 0°F to 250°F, it is suitable to any type of water application, as well as compressed air and ketones.
This is an example of our valve with the double seal:
We offer seven models of ProPress two-piece ball valves for potable and non-potable copper applications, as well as a ProPress automatic recirculation valve, check valve and butterfly valve. They are configured with a mix of connections, including press, female pipe thread and hose.
Our ProPress valves include Smart Connect technology, which makes it easier to identify unpressed connections. In addition to valves, the ProPress system includes elbows, adapters, caps, couplings, venturi, crossovers, tees, flanges, unions, reducers, valves, stub-outs, tools and accessories.
More information about ProPress valves can be found here.