Abstract: A control system is provided for providing a constant flow of air through a chamber, such as a fume hood, by measuring the pressure of the air outside of the hood and comparing it with the pressure of the air within the hood and adjusting the flow of air to achieve a constant pressure difference. The system is particularly applicable to fume hoods which have a sash which can be opened or closed or left in intermediate position; the present system will provide a constant air flow through the hood regardless of the sash position.

Abstract: An airflow measuring sound attenuator that profiles and stabilizes the pattern of air flowing out of attenuation throats and accurately measures the average velocity of air flowing through the attenautor by a pitot tube array mounted in the region of profiled and stabilized airflow.

Abstract: A traverse probe for insertion transversely with respect to the direction of bulk flow of an air or gas stream to sense and average a traverse of the static pressure and separately to sense and average a traverse of the combination of static and velocity pressure or total pressure of the stream. The probe includes along its length a spaced set of total pressure ports in the tube wall substantially aligned with the direction of flow in the zone of positive total pressure at the tube wall facing the direction of flow and first and second spaced sets of static pressure ports in the tube wall, one set aligned in each of the zones of static pressure only that lie at the tube wall adjacent to and on each side of the zone of positive total pressure. The set of total pressure ports is aligned on the bisector of the included angle between the sets of static pressure ports where the included angle is in the range of about 78.degree.-80.degree. for useful probe diameters.

Abstract: There is disclosed an improved "harmonic screw" type actuator wherein rotary motion of the power input component is converted into linear motion of the output component by means of a strain wave imposed upon a flexible sleeve member of the assembly, which is flexed into intermittent screw engagement by a member which is motor-driven to rotate relative to the periphery of the flexible sleeve; thereby causing progressively advancing/retreating inter-engagements of thread-like surfaces formed on the axially stationary and axially movable components of the system. A variety of automatic "fail-safe" provisions are included as well as means for manual operation in power loss situations.

Abstract: Methods and apparatus for determining the total flow rate of gaseous fluid passing through a plurality of conduits utilizing a plurality of total and static pressure sensing probes, the number of total pressure sensing probes being selected and deployed within each conduit to cover cross-sectional areas of substantially equal and corresponding size, each total pressure sensing probe being connected to one central pressure averaging manifold and each static sensing probe being connected to a second pressure averaging manifold, the pressure difference between the two pressure averaging manifolds being compared to determine the pressure difference as a measure of average velocity.In addition, the fluid flow to and from each manifold is controlled, as by means of a restriction, to impede the flow while providing a substantially laminar flow and a Reynolds number less than 4,000.

Abstract: Apparatus for equalizing the velocity of fluids flowing in duct work and the like which comprises one or more rigid honeycomb sections having a plurality of coaxial passages wherein the ratio of the surface area of each passage to its cross-sectional area is in the order of thirty or greater.

Abstract: Apparatus for equalizing the velocity of fluids flowing in duct work and the like which comprises one or more rigid honeycomb sections having a plurality of coaxial passages wherein the ratio of the surface area of each passage to its cross-sectional area is in the order of thirty or greater .Iadd.and the length of the individual passages is varied to provide longer passages in the center of the duct than along the sidewalls of the duct..Iaddend.