| 摘要 |
<p>A strainer for drilling, partic. in petroleum mining operations, comprises an internal armature and a cylindrical filtering device supported by the armature. The strainer includes a number of protective elements on its outer periphery. These protective elements are disposed longitudinally such that a plane tangent to two adjacent elements does not cut the outer surface of the filtering device. The protective elements are pref. rods regularly distributed around, and fixed directly by welding to, the outer surface of the filtering drive, in number such that the distance between a plane tangent to two adjacent rods and the filtering device is about 2 mm. Problems associated with high pressure drop through the strainer are avoided. The invention provides an outer armature which reduces the filtering surface only slightly and protects is effectively against deterioration caused by the surrounding strata and the casing.</p> |
