Mid pulse valve for measurement-while-drilling system

摘要

A metering valve (80A) for producing a mud-pulse in a mud-flow. The metering valve comprises a straight passage (182,482,582,682) for a straight stream of the mud flow and a detour passage (183,483,583,683) providing a tortuous path for the mud flow. A changeover means shifts a main stream of the mud flow between the straight passage and the detour passage.