Abstract: An apparatus for the condition checking of a screen cloth in a vibrating screen for drilling fluid, comprising a pump for drawing a drilling fluid sample from the bottom tray of the vibrating screen into the apparatus, a filter for filtering the drilling fluid sample, and a pressure gauge for measuring the pressure difference across the filter. A method for the condition checking of a screen cloth in a vibrating screen, comprising drawing a drilling fluid sample from the bottom tray of the vibrating screen, filtering the drilling fluid sample through a filter, and measuring the pressure difference across the filter.

Abstract: An apparatus is provided for cleaning a drill string of drilling mud during tripping, the apparatus being provided with a mass and a volume such that it is able to float on a surface of the drilling mud in the drill string during the tripping operation. The apparatus includes a wiper device which is bellows-shaped, and a weight which is fastened to the top of the wiper device.