Method and apparatus for diagnosis of liquid losses in pressure measuring transducers filled with pressure transmitting liquids
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Abstract
Described are method and apparatus for diagnosis of liquid losses in pressure measuring transducers filled with pressure transmitting liquids. Such pressure measuring transducers include a pressure sensor (3) arranged in a pressure measuring chamber (1), and a pressure transfer means (5) connected to the pressure measuring chamber (1) and sealed against external surroundings by a separating diaphragm (7), on which a pressure to be measured acts in measurement operation. A sealed inner space (15) thereof is composed of the inner spaces of the pressure transfer means (5) and the pressure measuring chamber (1) and is filled with a pressure transmitting liquid (17), which, in measurement operation, serves for transmitting pressure acting on the separating diaphragm (7) to the pressure sensor (3). Such pressure measuring transducers further includes an apparatus for detecting liquid losses (L). The apparatus for detecting liquid losses (L) includes a test element (25) arranged in the sealed inner space (15). The outer volume of the test element (25) is reducible for diagnosis of liquid losses (L). The apparatus for detecting liquid losses (L) further includes an evaluating unit (29), which serves, during diagnosis, for registering, as a function of a volume reduction (ΔV) of the test element (25), a pressure (p) measured by the pressure sensor (3), and, on the basis of this pressure (p) measured as a function of the volume reduction (ΔV), for detecting whether liquid (17) has escaped.
17 Citations
22 Claims
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1-11. -11. (canceled)
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12. A pressure measuring transducer comprising:
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a pressure measuring chamber;
a pressure sensor arranged in said pressure measuring chamber;pressure transfer means connected to said pressure measuring chamber, which is sealed against external surroundings by a separating diaphragm, and on which a pressure to be measured acts externally in a measurement operation; a sealed inner space, which includes the inner spaces of said pressure transfer means and said pressure measuring chamber, which is filled with a pressure transmitting liquid, and which serves in measurement operations, for transferring a pressure acting on said separating diaphragm to said pressure sensor; and an apparatus for diagnosis of liquid losses, which includes, arranged in said sealed inner space, a test element, whose outer volume located in said sealed inner space is reducible for diagnosis of liquid losses, and an evaluating unit, which serves during diagnosis for registering a pressure measured by said pressure sensor as a function of volume reduction of said test element, and, on the basis of pressure measured as a function of volume reduction, detects whether liquid has escaped. - View Dependent Claims (13, 14, 15, 16)
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17. A method for diagnosis of liquid losses of a pressure measuring transducer including:
- a pressure measuring chamber;
a pressure sensor means;an apparatus for diagnosis of liquid losses including a test element; and
an evaluation unit, the method, comprising the steps of;reducing the volume of the test element, until either a non-linear falling off of the measured pressure occurs, or until an upper limit for volume reduction is reached; upon occurrence of a non-linear decrease, a volume reduction associated therewith is compared with a reference value recorded in the case of intact pressure measuring transducer, and on occasion, occurring liquid loss is quantified on the basis of a difference between the associated volume reduction and the reference value. - View Dependent Claims (18, 19, 20, 21, 22)
- a pressure measuring chamber;
Specification