Pressure measurement and calibration apparatus using gravity-induced diaphragm deflection
First Claim
1. Pressure measurement and calibration apparatus, comprising:
- a pressure sensing assembly, said assembly including a deflectable diaphragm and means for detecting deflection of said diaphragm and for generating an output signal representative of said deflection;
means for controllably rotating said diaphragm about an axis normal to the direction of local gravitational acceleration on said diaphragm, whereby said diaphragm is capable of deflection in response to local gravitational acceleration on said diaphragm, said deflection of said diaphragm being variable as a function of the angle between said diaphragm and said direction of local gravitational force; and
means for controllably conducting a flow of a fluid against said diaphragm to substantially eliminate said deflection.
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Accused Products
Abstract
A pressure measurement and calibration apparatus for accurately detecting fluid pressures in the range of between approximately 0 and 1000 millitorr, and more particularly in the range of between 0 and 10 millitorr, and a method for calibrating an external pressure measuring device using the apparatus. The apparatus employs a pressure sensing assembly having a deflectable diaphragm and sensing electrodes. The assembly is rotated about an axis which is normal to the direction of local gravitational acceleration through preselected angles relative to the direction of local gravitational acceleration. The apparatus generates an output signal representative of the deflection of the diaphragm due to gravitational acceleration on the diaphragm at a given angular orientation. The apparatus then controllably conducts a fluid flow against the diaphragm at a sufficient pressure to substantially eliminate the deflection attributable to gravity on the diaphragm. The magnitude of the fluid pressure required to restore the diaphragm to its non-deflected state can then be computed with accuracy that is traceable to known primary standards.
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Citations
16 Claims
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1. Pressure measurement and calibration apparatus, comprising:
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a pressure sensing assembly, said assembly including a deflectable diaphragm and means for detecting deflection of said diaphragm and for generating an output signal representative of said deflection; means for controllably rotating said diaphragm about an axis normal to the direction of local gravitational acceleration on said diaphragm, whereby said diaphragm is capable of deflection in response to local gravitational acceleration on said diaphragm, said deflection of said diaphragm being variable as a function of the angle between said diaphragm and said direction of local gravitational force; and means for controllably conducting a flow of a fluid against said diaphragm to substantially eliminate said deflection. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of calibrating an external pressure measuring device at fluid pressures in the range of between approximately 0 and 1000 millitorr, comprising the steps of:
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a) providing a pressure measurement and calibration apparatus comprising a pressure sensing assembly, said assembly including a deflectable diaphragm and means for detecting deflection of said diaphragm and for generating an output signal representative of said deflection, means for controllably rotating said diaphragm about an axis normal to the direction of local gravitational acceleration on said diaphragm, whereby said diaphragm is capable of deflection in response to local gravitational acceleration on said diaphragm, said deflection of said diaphragm being variable as a function of an angle θ
between said diaphragm and said direction of local gravitational acceleration, and means for controllably conducting a flow of a fluid against said diaphragm to substantially eliminate said deflection;b) orienting said diaphragm to a reference orientation and establishing an output signal representative of said reference orientation of said diaphragm; c) rotating said diaphragm about said axis through a preselected angular increment relative to said reference orientation to establish a gravity-induced deflection of said diaphragm at a corresponding first angular position of said diaphragm; d) detecting said deflection of said diaphragm and generating an output signal representative of said deflection; e) controllably conducting a flow of a fluid against said diaphragm to substantially eliminate said deflection of said diaphragm; f) permitting said fluid flow to stabilize against said diaphragm at a pressure Px ; g) exposing said external pressure measuring device to said fluid flow at said pressure Px through isobaric coupling means disposed between said diaphragm and said external pressure measuring device; and h) calibrating said external pressure measuring device at said pressure Px. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification