Busak + Shamban now offers three solutions for sealing in EGR (exhaust gas recirculating) valves used in diesel engines. Although useful in preventing NOx emissions, EGR valves run into problems when diesel fuel builds up carbon deposits. Busak + Shamban offers Double Delta seals, Glyd Ring II seals and Variseals to combat these problems. A Double Delta seal, consisting of a PTFE component which rides on the shaft and is energised by an O-ring, can be used to improve valve performance by creating a balance between the desired leakage, friction and response time of the valve. To reduce tolerances and allow greater flexibility in electronic program controls, a Glyd Ring II, in which the elastomer is bonded to the PTFE, is available to control tolerance stack up and performance variation. For the most demanding applications, a Variseal, in which the elastomer is replaced with a slant coil spring to energise the seal, is available to make sealing function and friction more consistent, especially in near gas-tight and high temperature applications.
