Abstract: A gas purification unit includes a gas purification vessel (12) and at least one of inlet conduit means (18, 20, 34) for connecting a feed gas source (16) to the gas purification vessel and outlet conduit means (36, 22, 24) for connecting the gas purification vessel (12) to at least one downstream gas processing unit. Each of said inlet and outlet conduit means includes at least two subsidiary pipes arranged in parallel and a common pipe (34, 36), each subsidiary pipe being in fluid flow communication with the common pipe and having a flow control valve (18, 20, 22, 24) operating in unison with the flow control valve of the or each other subsidiary pipe. The use of at least two valves in unison increases the reliability of the unit. The use of at least two smaller valves in place of a single large valve also increases the reliability.

Abstract: A gas purification unit includes a gas purification vessel (12) and at least one of inlet conduit means (18, 20, 34) for connecting a feed gas source (16) to the gas purification vessel and outlet conduit means (36, 22, 24) for connecting the gas purification vessel (12) to at least one downstream gas processing unit. Each of said inlet and outlet conduit means includes at least two subsidiary pipes arranged in parallel and a common pipe (34, 36), each subsidiary pipe being in fluid flow communication with the common pipe and having a flow control valve (18, 20, 22, 24) operating in unison with the flow control valve of the or each other subsidiary pipe. The use of at least two valves in unison increases the reliability of the unit. The use of at least two smaller valves in place of a single large valve also increases the reliability.

Abstract: A Measurement-while-Drilling method and apparatus for obtaining information about a formation uses sensors on substantially non-rotating pads attached to a rotating housing that is part of the drilling assembly. The pads make contact with the formation. The sensors may be density, NMR, resistivity, sonic or electromagnetic. The NMR sensors may use a static magnetic field that can be either radial or longitudinal in direction. The resistivity sensors may involve direct measurement of leakage current or may rely on induction methods. The sonic sensors may be three component transmitters and/or receivers for determining compressional and shear velocities of the formation and may also be used to image the formation in a VSP or a reverse VSP. In an alternate arrangement, the sensors rotate with the drill bit. A downhole microprocessor analyzes the data to improve signal-to-noise ratio and to reduce redundancy in the acquired data.