pqq caps with biopqq
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On the other hand, HALS are a unique class of stabilizers that work by scavenging free radicals generated during the photodegradation process. By trapping these free radicals, HALS significantly slow down the degradation of the polymer chains, preserving the mechanical properties of the plastic. This mechanism allows HALS to be effective even in small concentrations, making them a popular choice in various applications.
light stabilizers for plastics...
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VMQ (silicone)
Oil seals come in a wide range of types, and they also have various sizes.
When selecting the right oil seal for your machine from among these many varied types of oil seals, the following two criteria are very important.



Replacing the sump gasket
This is a specific type of synthetic rubber that’s commonly used in o-rings, gaskets, oil seals, sterile & chemical resistant gloves, and other molded items. Viton has a high density and it possesses the widest temperature range of -40 degrees Fahrenheit to more than 400 degrees Fahrenheit. This is why it’s highly preferred as the best material for higher temperature applications.



The most important function of an oil seal is to protect all types of sleeves, roller bearings, and balls located in the rotary shafts. These seals also prevent two fluids from mixing, such as water and oil.
The major cause of extrusion and nibbling is stress caused by high pressure. This is commonly noticed when the oil seal has a chipped or nibbled look. In fact, in some cases, the surface of the seal tends to peel on its own, which makes it have a shaved look. What the stress does is that it increases the clearance gap between the mating edges, which causes the seal to get entrapped, and then leads to severe physical damage.
Material selection is important to the life of a radial shaft seal. The elastomer’s resistance to temperature, abrasion, chemicals, weather, sunlight, and ozone can affect a profile’s longevity and performance. The two most prevalent materials are Nitrile and Viton. See our Oil Seal Materials page for details on compounds and chemical compatibility.
Metal O.D. wall
(with a reinforcing inner metal case)
Thoroughly clean the sleeve at the back of the pulley, and look for any roughness on it where it touches the seal. If necessary, smooth it with fine wet-and-dry abrasive paper.


There are a wide range of oil seals to select from for any number of uses, so this guide will break down the most common seals to help you choose the right one for whatever piece of machinery you are working on.