Abstract: An assembly for measuring the mass flow and flow rate of gases such as are used in semiconductor fabrication processes. The assembly includes an axial flow passage, viz., a capillary tube with a bore of about 0.050 inch diameter and a wall thickness of about 0.002 inch, having a downstream end connected to a diffuser section having an axially symmetric, diverging passage. Gas exiting the diffuser section has a low pressure drop because the gas has expanded at a low, controlled rate, converting velocity head into pressure head, and because the tube and diffuser section passage are in-line, eliminating right-angle turns. The assembly also includes two resistance thermometers, coils of iron-nickel alloy wire about 0.0004 inch in diameter, providing a differential temperature measurement with a time constant of less than 4 seconds.

Abstract: A split path mass flowmeter includes a housing having a longitudinally extending bore within which a flow splitter is positioned. The flow splitter includes a tapered portion having a taper corresponding generally to that of a tapered portion of the bore. The tapered portion of the flow splitter is nested within the tapered portion of the bore, the tapered portions of these elements thereby forming a self-holding retention section for non-adjustably retaining the flow splitter within the bore. The retention section may taper outwardly or inwardly in the direction of fluid flow. A calibration section may precede or follow the retention section or may be combined into the retention section. Further, a recovery section may be separately disposed downstream of the retention and calibration sections or may be combined along with the calibration function in the retention section.

Abstract: A flow meter has an elongate housing with a fluid inlet, a fluid outlet and an axial passage therebetween. The fluid passage contains a flow sensor assembly operationally connected in parallel to a flow splitter section. The flow sensor assembly has a flow tube forming an axial passage therethrough and the flow tube has a thermally diffusive sensor region. An upstream resistance thermometer and a downstream resistance thermometer are in thermal contact with the sensor region. The sensor region can additionally contain an electrically insulating coating on its outside surface and resistance thermometers formed by winding a single layer of a fine, uninsulated wire around its outside surface. The sensor assembly can be surrounded by inner and outer housings made of electrically and thermally conductive material connected to the flow tube near the ends of the sensor region and grounded to a printed circuit board.

Abstract: A disconnectable flow connector is formed of (a) a frusto-conical taper pin having a longitudinal bore through which the end portion of a flow tube of a mass flow sensor is inserted and secured and (b) a connector base containing a matched frusto-conical taper bore. The taper pin can be press-fit into the taper bore to form a fluid flow passage having a leakage level less than about 10.sup.-9 scc/sec helium.

Abstract: A disconnectable flow connector is formed of (a) a frusto-conical taper pin having a longitudinal bore through which the end portion of a flow tube of a mass flow sensor is inserted and secured and (b) a connector base containing a matched frusto-conical taper bore. The taper pin can be press-fit into the taper bore to form a fluid flow passage having a leakage level less than about 10.sup.-9 scc/sec helium. with a series of spaced apart, transverse grooves separated by lands in sealing engagement with the matched taper bore.

Abstract: A hermetically sealed, precision fluid valve assembly including a ball valve element is disclosed. The assembly includes a valve element retainer comprising a thin, flexible member having a first portion operatively associated with the valve element and a second portion, extending from the first, secured to the body of the valve assembly. The valve element retainer guides the motion of the valve element and is designed to reduce friction and eliminate the generation and entrapment of contaminants, thereby minimizing hysteresis in the operation of the valve.

Abstract: An improved thruster for propelling borescopes by the reaction forces generated by pressurized fluid expelled from the thruster has a desirably small cross-sectional profile made possible by its novel construction. The basic embodiment of the thruster comprises an elongated hollow cylinder sealed at one end by a bulkhead and supplied with pressurized fluid at the opposite, open end. A thin slot cut through the cylinder wall permits pressurized fluid to exit the hollow interior space of the cylinder, producing a reaction force useful in propelling a borescope tip to which the thruster is fastenable.

Abstract: An apparatus for remotely orienting the distant tip of a flexible borescope cable to point in a desired direction utilizes a plurality of vertabrae-like annular disks disposed transversely within the hollow interior of the distal end of the flexible cable. Fine, flexible wires fabricated from a shape memory effect (SME) alloy are fixedly attached to outermost disk, and extend longitudinally backwards slidably through aligned holes in the other disks, and slidably through hollow flexible tubes rearward of the innermost of the disks.

Abstract: A method and apparatus for spatially orienting a remote flexible member such as the tip of a borescope to point in a desired direction employs heating to its transition temperature a shape memory efffect SME alloy actuating element coupled to the tip and cable. In one embodiment, an elongated helical spring fabricated from an SME alloy such as NI--TI or CU--ZN--AL is longitudinally disposed between the remote end of a borescope cable, and the borescope tip. An electrical resistance wire heater in contact with the spring and energized by an electrical power source controlled by an observer at the near end of the cable is used to heat a selected part of the spring to the transition temperature of the SME alloy of which it is fabricated, producing a controlled deflection of the borescope tip to point in a direction directed by the observer.

Abstract: A method and apparatus for propelling a borescope being used to inspect inaccessible areas comprises one or more reaction jets attached to the borescope, the reaction jets expelling gas, liquid or other fluids to produce a reaction thrust force on the borescope. In one embodiment, a reaction jet is fastened to the remote head of an articulateable borescope, and the propulsion direction is controlled by an operator who views a desired aim point at the output end of the borescope cable, and articulates the borescope head to point at the desired aim point. In another embodiment, the orientation of the thrust vector of the reaction jets is controllable, permitting an operator to control the direction of travel of a borescope not necessarily possessing an independent articulation capability.