Apparatus for testing valve actuators

Abstract

An apparatus is disclosed for subjecting a test valve actuator to torque loads which simulate the torque loads an actuator would be expected to experience in field operation when opening and closing a butterfly-type valve in a fluid conduit. The apparatus includes a frame supporting both a drive shaft and a tail shaft mounted for rotation about horizontal axis of rotation. The test actuator is mounted on the frame and coupled to the drive shaft for rotating the shaft 90.degree. about its axis. A sprocket fixed to the drive shaft is connected by a link chain to a sprocket fixed to the tail shaft. The sprockets are selected to have a 3 to 1 gear reduction ratio with the tail shaft rotating 3 degrees for each degree of rotation of the tail shaft. A mass depending from the tail shaft generates a torque load at the tail shaft equal to one third the dynamic torque load for corresponding positions of the actuator. The torque load is transmitted to the actuator through the sprockets and link chain with the torque amplified three times to approximate the dynamic torque load. A second mass, pivotally supported away from the tail shaft, is engaged and rotated as the first mass approaches a position corresponding with a valve opened position. The torque produced by the second mass together with the torque produced by the first mass equals one-third the expected seating torque load which is transmitted to the actuator and amplified three times by the sprockets and link chain to approximate the seating torque. Circuitry is disclosed for permitting repetitious operation of the apparatus to cycle the actuator from opened position to closed position and back to opened position.