ValveEdition.pdf | Page 89

Ball Valve Accessories Repair Kits for High Pressure Ball Valves BV2, BV2B & BV3 Repair Kits Repair kits for use with high pressure ball valves (BV2, BV2B & BV3) BV2 & BV3 (Block Style) Standard Repair Kit 2 POM Ball Seats 2 NBR Adapter O-Ring 1 Stem O-Ring 1 POM Stem Seal Ring BV2B (Round Body) Standard Repair Kit 2 POM Ball Seats 2 NBR Adapter O-Ring 1 Stem O-Ring 1 POM Stem Seal Ring O-Ring General Principles The simple geometry is the main characteristic of an O-Ring which in conjuction with proper elastomer selection results in a low cost, easy to use and efficient sealing system. Elastometric materials, when compressed, react like a high viscosity fluid which transmits applied stress in every direction; consequently, the O-Ring serves as a barrier, blocking the leak paths between the sealing surfaces. Technical sealing has been defined by DIN standards as follows: • “Static Seal” - The sealing action created between two mating surfaces with no leakage of liquid or minimal duffusion of gas. • “Dynamic Seal” - The mating surfaces have relative movement with minimal leakage of liquid (useful to protect the sealing efficiency, acting as a lubricant). O-Rings offer several advantages over the sealing systems: simplicity of construction, standardized seal dimensions, wide selection of materials, suitability for both static and dynamic applications, standard dimensioning of glands, low cost due to high volume manufacturing. Sealing is always acheived through a positive compression of squeezing action, resulting in a deformation of the O-Ring cross section. The most important sealing characteristic of an O-Ring is its resistance to compression set or residual deformation. 88 DNP Americas | 281-388-0253 | fax 281-388-1902 | www.dnpamericas.com