(under subclass 231) Devices combined with a pipe having solid walls formed with perforations cooperating with the straining openings of the helical element to pass the strained fluid.
(1) Note. A skeleton structure built in the shape of a pipe
is not considered a solid pipe with perforations. See subclasses 231 and 232 for such structure.
SEE OR SEARCH THIS CLASS, SUBCLASS:
232, for screens having a perforated pipe and a helical element and in which the helical element has spacing lugs.
