US Patent 8408519 Gate valve with lubricated secondary seal

A gate valve includes a pair of opposing housing members, a gate, primary sealing sleeves and a secondary sealing member. The primary sealing sleeves are disposed in each of the housing members. The gate is configured to slidably pass through a transverse gate chamber defined when the housing members are joined together. The secondary sealing member is secured between the housing members and includes at least one passage or aperture configured to allow lubricating fluid to be applied through at least one of the housing members through the secondary sealing member and onto the gate.