Polyurethanes are formed by reacting a polyol an alcohol with more than two reactive hydroxyl groups per molecule with a diisocyanate or a polymeric isocyanate in the presence of suitable catalysts and additives. In this example, the equivalent is 104. Dozens of specialized formulations have been developed to maximize performance in specific application situations like improved low temperature, acid, amines, plasma, steam, food and medical grade, high pressure and explosive decompression resistance. After being held for five minutes at 100% stretch, it must retract to within 10% of its original length within five minutes of release. However, silicone elastomers as a group, have relatively low tensile strength, poor tear strength and little wear resistance.
More precisely, a compound refers to a specific blend of chemical ingredients tailored for particular required characteristics to optimize performance in some specific service. Permeability and compression set are excellent. These two lubricants are described in the following paragraphs. Silicones can be synthesized with a wide variety of properties and compositions. See Tables below for description of these types. Click a compound number below to view the Parker material datasheet. Contact us to learn more about the incredible performance of our sealing solutions, or to reach a technical sales representative who can assist you with material selection for your specific application needs.
Superior mechanical characteristics, particularly high strength, helps reduce extrusion and wear. Use only a thin film of Super-O-Lube on silicone rubber if the temperature will exceed 149°C 300°F. A mold scrapped as defective will not be replaced unless demand justifies the expense. Click a compound number below to view the Parker material datasheet. Click a compound number below to view the Parker material datasheet. It has good mechanical properties over a wide temperature range.
It should be noted that although this method has been used successfully, it is not generally recommended. Extrusion Extrusion of O-rings may also be prevented by the use of anti-extrusion back-up devices. The rubber compounder may then add various reinforcing agents such as carbon black, curing or vulcanizing agents such as sulfur or peroxide, activators, plasticizers, accelerators, antioxidants, or antiozonants to the elastomer mixture to tailor it into a seal compound with its own distinct physical properties. The O-Ring is confined in a triangular recess made by machining a 45 degree angle on the male cover. Click a compound number below to view the Parker material datasheet. With higher pressures, the combination of pressure and material shore hardness determine the maximum clearance that may safely be tolerated see Limits for Extrusion. Contact Parker O-Ring Division at 859-269-2351 for design and pricing assistance.
The acrylonitrile content of nitrile sealing compounds varies considerably 18 to 50%. Materials with other than standard shrinkage will give different dimensions and tolerances. Gland design recommendations for a reciprocating seal are provided on pages 40 and 41. Contact the division for availability. It is caused by absorption of gas at high pressure and the subsequent rapid decrease in pressure. The Parbak Back- Up Rings in Zatkoff Product catalog, describes in greater detail Parker Parbak back-up rings, and provides size and part number data.
The following charts are included to facilitate engineering analysis. As with all chemical reactions, temperature is responsible for the speed of reaction. V1164-75 -29°C to +135°C -20°F to +275°F , cpd. Butyl has great chemical resistance and low permeability but not typically recomended in O-Ring and seal applications due to poor short term rebound. Extra charges may apply for testing and documentation.
An undercut or dovetail groove has proven beneficial in many applications to keep the O-ring in place. Port O-Ring Name Parker Part No. Dynamic seals are defined by one of the gland parts having movement relative to the other part. Normally acceptable tolerance extremes, wide service temperature ranges, and fluid media that cause high swell of the elastomer are conditions that cannot be tolerated in this type of groove design. Polyacrylate is a transmition fluid specialy material utilized in lower temperature applications with risk of slightly more swelling compared to Polyacrylate. Parker O-Lube Parker O-Lube is an outstanding general-purpose grease intended for use with O-ring and other seals in hydrocarbon service.