Fluid measuring apparatus
First Claim
1. Fluid measuring apparatus comprising:
- a housing having an elongated cavity enclosed on its sides;
a first thin elongated hot wire bent in half to extend along the length of the cavity away from a junction;
a second thin elongated hot wire bent in half to extend along the length of the cavity away from the junction;
first means at the junction for supporting the ends of each hot wire in spaced electrically isolated relationship from each other and connecting one end of the first and second hot wires to each other to form in effect a first single hot wire equal in length to the first and second hot wires;
second means spaced along the length of the cavity from the junction for supporting the middle of the first hot wire to exert tension thereon as the length of the first hot wire changes;
third means spaced along the length of the cavity from the junction for supporting the middle of the second hot wire to exert tension thereon as the length of the second hot wire changes;
means for forming in the housing a fluid entrance to the cavity;
means for forming in the housing a fluid exit from the cavity longitudinally spaced from the entrance so the hot wires lie between the entrance and the exit; and
means for measuring the change in resistance of the hot wires.
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Accused Products
Abstract
A housing has elongated cavities in which four hot wires forming the arms of a bridge are disposed. Each hot wire comprises a first segment bent in half to extend along the length of the cavity away from a junction, and a second segment bent in half to extend along the length of the cavity away from the junction in the opposite direction from the first segment. The junction is centrally located relative to the ends of the cavity. The first and second segments are electrically connected to each other at one end and are electrically connected to other hot wires in the bridge at the other end by a printed circuit board at the junction. The middle of each segment is wrapped around first and second closely spaced rods deformed to exert tension on the segment. The circuit board is located in a chamber having a larger cross section than the cavities. In using the apparatus for chromatography, unknown gases in a carrier enter one of the cavities near the chamber. A reference gas enters the chamber to prevent the unknown gases from flowing to the chamber. The gases exit from the ends of the cavity.
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Citations
19 Claims
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1. Fluid measuring apparatus comprising:
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a housing having an elongated cavity enclosed on its sides; a first thin elongated hot wire bent in half to extend along the length of the cavity away from a junction; a second thin elongated hot wire bent in half to extend along the length of the cavity away from the junction; first means at the junction for supporting the ends of each hot wire in spaced electrically isolated relationship from each other and connecting one end of the first and second hot wires to each other to form in effect a first single hot wire equal in length to the first and second hot wires; second means spaced along the length of the cavity from the junction for supporting the middle of the first hot wire to exert tension thereon as the length of the first hot wire changes; third means spaced along the length of the cavity from the junction for supporting the middle of the second hot wire to exert tension thereon as the length of the second hot wire changes; means for forming in the housing a fluid entrance to the cavity; means for forming in the housing a fluid exit from the cavity longitudinally spaced from the entrance so the hot wires lie between the entrance and the exit; and means for measuring the change in resistance of the hot wires. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. Fluid measuring apparatus comprising:
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a housing having an elongated cavity enclosed on its sides; a thin elongated hot wire bent in half to extend along the length of the cavity; means at one area of the cavity for supporting the ends of the hot wire in closely spaced, electrically isolated relationship from each other; first and second closely spaced rods at another area of the cavity spaced from the one area to support the middle of the wire, the middle of the wire being wrapped around the rods and the rods being deformed to exert tension on the hot wire to keep the hot wire taut as its length changes; means for maintaining the spacing of the first and second rods; means for forming in the housing a fluid entrance to the cavity; means for forming in the housing a fluid exit from the cavity longitudinally spaced from the entrance so the hot wire lies between the entrance and the exit; and means for measuring the change in resistance of the hot wire. - View Dependent Claims (18)
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19. Gas chromatographic apparatus comprising:
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a housing having a first elongated cavity and a second elongated cavity; a chamber at one end of the first cavity having a cross section larger in area than the first cavity; a first thin elongated hot wire extending along the length of the first cavity; first means in the chamber for supporting the first hot wire in spaced relationship from the sides of the cavity; second means at an area of the cavity spaced from the chamber for supporting the first hot wire in spaced relationship from the sides of the cavity; means for forming in the housing a fluid entrance to the chamber; means for forming in the housing near the chamber a fluid entrance to the first cavity; means for forming in the housing a fluid exit from the first cavity longitudinally spaced from the entrance to the first cavity so the hot wire lies between the entrance to the first cavity and the exit from the first cavity; a second thin elongated hot wire supported to extend along the length of the second cavity in spaced relationship from the sides thereof; means for forming in the housing a fluid entrance to the second cavity; means for forming in the housing a fluid exit from the second cavity longitudinally spaced from the entrance to the second cavity so the hot wire lies between the entrance to the second cavity and the exit from the second cavity; a source of one or more unknown gases in a carrier of reference gas coupled to the entrance to the first cavity; a source of reference gas coupled to the entrance to the second cavity; means for coupling a reference gas to the chamber to prevent the one or more unknown gases in a carrier from flowing to the chamber; and means for measuring the difference in the change in resistance of the first and second hot wires responsive to the reference gas and the one or more unknown gases in a carrier.
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Specification