CS series desander is the second class solids control equipment of drilling-fluid solid control system. The design of desander cyclones are based on the centrifuge-setting principle of particles. The separating drilling fluid goes into the cyclone along its inner-wall at a certain pressure and speed made by the pump. The great particles are going down spirally along the inner-wall of the cyclone at the centrifugal force and the gravity , then running out through the underset nozzle and falling down on the close-mush shale shaker for further separation . The other fluid goes up along the centre of the cyclone spirally, and goes into the second class separating equipment desilter for further separating.