Capacitive manometer having reduced process drift
First Claim
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1. A capacitive manometer, comprising:
- a housing;
a diaphragm inside the housing;
a flow passage through which gas enters the housing; and
a filter in the flow passage, the filter including a body having a downstream end which is spaced less than about 5 mm from the diaphragm, the body having a length along the flow passage which is greater than a maximum transverse dimension of the body, the filter including at least one gas passage extending along the length of the body, the gas passage being capable of removing condensable vapors from the gas.
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Abstract
A capacitive manometer includes a flow passage through which gas can enter the manometer, a deflectable diaphragm, and a filter arranged in the flow passage. The filter is capable of removing condensable vapors from the gas so that the condensable vapors do not reach and deposit on the diaphragm. The capacitive manometer can include a cooling unit arranged to cool the filter so as to enhance removal of condensable vapors from the gas by the filter. The capacitive manometer can include a baffle having gas passages distributed to control distribution of condensable vapors, which pass through the baffle, on the diaphragm.
58 Citations
26 Claims
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1. A capacitive manometer, comprising:
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a housing; a diaphragm inside the housing; a flow passage through which gas enters the housing; and a filter in the flow passage, the filter including a body having a downstream end which is spaced less than about 5 mm from the diaphragm, the body having a length along the flow passage which is greater than a maximum transverse dimension of the body, the filter including at least one gas passage extending along the length of the body, the gas passage being capable of removing condensable vapors from the gas. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A capacitive manometer, comprising:
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a housing; a diaphragm inside the housing; a flow passage through which gas enters the housing; a filter in the flow passage upstream of the diaphragm, the filter including at least one gas passage and being capable of removing condensable vapors from the gas; and a cooling unit disposed along the flow passage and operable to cool the filter. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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19. A capacitive manometer, comprising:
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a housing; a diaphragm inside the housing; a flow passage through which gas enters the housing; and a filter arranged along the flow passage upstream of the diaphragm, the filter including at least one gas passage and being capable of removing condensable vapors from the gas, the at least one gas passage having (i) a maximum transverse dimension, (ii) a length and (iii) an aspect ratio defined by a ratio of the length to the maximum transverse dimension of at least about 10. - View Dependent Claims (20, 22)
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21. A capacitive manometer, comprising:
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a housing; a diaphragm inside the housing; a flow passage through which gas enters the housing; a filter arranged along the flow passage upstream of the diaphragm, the filter including at least one gas passage and being capable of removing condensable vapors from the gas, the at least one gas passage having (i) a maximum transverse dimension, (ii) a length and (iii) an aspect ratio defined by a ratio of the length to the maximum transverse dimension of at least about 10; and a cooling unit arranged along the flow passage and operable to cool the filter.
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23. A capacitive manometer, comprising:
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a housing; a diaphragm inside the housing, the diaphragm having a face exposed to a gas; a flow passage through which the gas enters the housing; and a baffle disposed in the flow passage upstream of the diaphragm, the baffle including a plurality of gas passages extending therethrough, the gas passages having an arrangement in the baffle that controls spatial deposition of condensable vapors contained in the gas, which pass through the gas passages and deposit on the face of the diaphragm, such that condensable vapors deposited on the face of the diaphragm cause substantially no drift of the capacitive manometer. - View Dependent Claims (24, 26)
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25. A capacitive manometer, comprising:
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a housing; a diaphragm inside the housing, the diaphragm having a face exposed to a gas; a flow passage through which the gas enters the housing; a baffle disposed in the flow passage upstream of the diaphragm, the baffle including a plurality of gas passages extending therethrough, the gas passages having an arrangement in the baffle that controls spatial deposition of condensable vapors contained in the gas, which pass through the gas passages and deposit on the face of the diaphragm, such that condensable vapors deposited on the face of the diaphragm cause substantially no drift of the capacitive manometer; and a cooling unit disposed along the flow passage and operable to cool the filter.
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Specification