Usually black O-ring material popular for NBR, Taiwan brand - Wall top seal OTP, specialized for Ningbo, Guangzhou, Shanghai, Beijing and other sales of imported O-ring. Of course, there may be a silicon fluorine rubber and silicone rubber, then how is the difference? Nitrile rubber O-rings and fluorine rubber O-ring compared to fluorocarbon rubber tensile rate is relatively low, so it would be more difficult to pull. Silicone silicone rubber O-rings are relatively soft texture, stretch rate is high. Usually see black O-rings are generally nitrile rubber material. Select O-ring hardness choose to import O-ring hardness is more important to use the O-ring in a ring. O-ring low hardness, easy to O-rings, but if the O-ring hardness is too low, then the O-ring is prone to flaking, and extrusion installation damage and other adverse conditions; if the O-ring hardness is too high, it is not easy O-ring installation. Typically O-ring hardness of 40 to 90 degrees (Shore hardness), in use O-ring is generally used in 70 degrees is more appropriate, but the silicone O-ring is an exception, the general use of 60 degrees. The specific O-ring hardness selection, please consider the environmental conditions O-ring actually used. We sell in Ningbo NBR nitrile rubber O-ring made of acrylonitrile and butadiene polymerization, the general temperature range of -40 ~ 120 ℃. NBR rubber is one of the most commonly used rubber seals and O-rings now. b. Use NBR NBR rubber manufactured parts, especially the sealing parts (such as O-rings, star-ring, ED ring, polyurethane seal, rubber flat gaskets, etc.) are widely used in the fuel tank, oil tank , petroleum-based hydraulic oil, gasoline, water, silicone grease, silicone, diester-based lubricants, hydraulic oil, glycol-based fluid medium. NBR can say is currently the most widely used and lowest cost rubber seal. Advantages c. NBR nitrile rubber O-rings? resistance to oil, water resistance, solvent resistance and excellent resistance to high pressure oil properties.