Valves Wedge

WHAT IF, AT BIRTH, YOU WERE ABLE TO CHOOSE YOUR HEART ? Would you choose a cheap heart which broke down regularly or would you choose a first-rate quality heart that remained healthy and strong throughout your entire life? 20-09-2017

Valves Have Long Life Specifications

When a valve is first made, it works wonderfully, however with time, wear and tear takes its toll and the major differences between good and bad quality valves become apparent. While the high-quality valve will continue to execute its job effortlessly, the cheaply made valve will require constant maintenance, at a hefty price too.

Below are the reasons as to why an AVK valve should be chosen -

The Rubber Absorbs Impurities

A correct rubber compound is soft enough to absorb impurities, yet strong enough to wash the impurities through when the valve is opened again. This means that the rubber surface will regain its original shape securing a drop-tight sealing. Tests prove that the rubber surface of a DN 250 wedge absorbs impurities up to Ø8.7 mm.

Safe Operation and Long Durability

A fixed wedge nut reduces the number of moveable parts and prevents vibration, thus preventing corrosion, malfunction and water hammer. The wedge nut is made of dezincification resistant brass with lubricating abilities which provides optimum compatibility with the stainless-steel stem. It is sealed at the top and bottom with rubber to prevent corrosion.

High Quality Rubber Compounds

The ductile iron core is fully vulcanized with rubber both inside and outside. A minimum of 1.5 mm rubber is applied on all pressure bearing surfaces and a minimum of 4 mm on all sealing surfaces, regardless of the design.

A unique vulcanization process ensures that the entire wedge core is covered with rubber and that the shoes are attached to the wedge core. This process is one of the secrets to keeping the wedge protected from corrosion and thus securing long life and smooth operation of the valve.

Double Bonding Secures Excellent Rubber Adhesion

The wedge core is immersed in two different baths. The first is implemented to prepare the ductile iron core and the second is to vulcanize the rubber to the core. Since no international bonding standard is available, AVK has developed its own harsh test method to ensure that the adhesion also withstands extremely intense situations. Testing is done both during production and after immersion in 90°C water for 3 weeks. When peeling off rubber from the core, the core must still be covered with rubber.

Compression Set Ability to Regain Original Shape

The rubber is deformed by 25% of its original thickness at a constant temperature for a specific time. The pressure on the rubber is relieved and the layer thickness is measured after half an hour. The smaller the deformation, the better the memory effect. EN 681-1 states that these are the minimum requirements for the compression set value. The smaller the permanent deformation, the better the compression set.

Resistance to Water Treatment Chemicals

The rubber, which is a complex formulation of many ingredients, is developed and tested by AVKs own R&D scientists. AVK has the most advanced state of the art mixing facility which ensures repeatability and high performance materials. Tests are continuously carried out to ensure that the correct rubber compound is applied for the right area of use. The rubber compounds are also ozone tested.

Avoid Contamination, Minimize Formation of Biofilm

AVK’s EPDM rubber recipes are composed with focus on minimizing the formation of biofilm. As a result, the rubber will not provide a breeding ground for bacteria.

Drinking Water Approvals

All rubber compounds are approved according to international standards such as WRAS and NSF-61.



The wedge is the heart of gate valves

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