Abstract: A method and apparatus for the measurement of fluid flow through a conduit comprises determining, from one or more measuring elements, a first value related to the velocity of fluid flowing through the conduit. A second value, related to the temperature of fluid ambient to the conduit, is also determined. The method further includes establishing a third value related to the physical configuration of the measuring means. The first, second and third values are then used to calculate a power dissipation factor of the measuring means to be used in calculating a velocity indication which substantially eliminates errors due to changes in ambient temperature and caused by velocity cooling within the conduit.

Abstract: An apparatus for the measurement of fluid flow through a conduit comprises at least one thermally sensitive element capable of producing a measurement value related to temperature located within the conduit. This element is exposed to the flow of fluid through the conduit. A second thermally sensitive element is capable of producing a reference value related to temperature of fluid ambient to the conduit. The reference value is substantially unaffected by heat generated by the second thermally sensitive element. An electrical circuit is provided for determining the measurement and reference values and for using the same to produce an indication which substantially eliminates errors due to changes in the ambient temperature and caused by velocity cooling of the first thermally sensitive element. This indication is representative of fluid flow through the conduit.

Abstract: Improved structure for measuring the air flow in large conduits, such as those used to supply air conditioning and heating ducts, by sampling substantially all of the cross sectional area of the conduit in a given transverse plane to obtain an average electrical signal which is compared with a reference signal to obtain a measured voltage corresponding to average flow.

Abstract: A quick-disconnect coupler for a light-transmitting flowcell having in a sight path light-input and light-output windows, respectively, for interposition intermediate a light source and a light detector, respectively, at least in part through a pair of elongated light-transmitting elements, and a support member for the flowcell. There is provided a slip-on flowcell supported on the support member, and a quick-release clamp comprising a pair of jaw members having a pair of corresponding end portions and comprising mounting means for movement of said end portions respectively toward and away from each other and said flowcell windows. The light-transmitting elements have terminals supported in the respective jaw members for alignment with the respective flowcell windows and in contact with said flowcell in the operative positions of the jaws.