Flow measuring needle and orifice for flow meter

Abstract

A remote volume flow meter is disclosed in which a variable density optical filter attached to a moving diaphragm indicates flow by filter position. The diaphragm has a hole, which hole travels along a needle. The needle is mounted to the housing via a needle stem. Excursion of the diaphragm at the hole occurs against a spring force. Upon movement against this spring force the diaphragm hole sees a changing area defined by the needle. Typically, the needle is of overall cylindrical configuration with one or more linearly tapering grooves extending from one end of the needle to another end of the needle. These grooves taper from a small interruption of the cylindrical cross-section at the low mass flow rate end of the needle to a large interruption of the cylindrical cross-section of the needle at the high mass flow rate end of the needle. Centrally of the needle and protruding to the high flow rate end of the needle there is provided a threaded adjustment needle. This adjustment needle is for advancement into the deepest portion of the tapering grooves.

Dependencies are inferred from the claim text.