EP0018221A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Method of and apparatus for measuring the amount of combustibles present in a gas
Assignee: Ametek Inc
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Filing: 1980-04-18
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Granted: —
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Expires: 2000-04-18
Abstract
Abstract A detector or measuring bridge (12) and a reference bridge (14) receive input signals from a regulated power source (20) and generate output signals through feedback control circuits (56, 68) to a galvanometer (76). Each bridge (12, 14) includes a filament (32, 40) exposed to a gas being measured. The detector bridge filament (32) is coated with a catalyst and the reference bridge filament (40) is not. Initially, the bridges are calibrated for operation of the exposed filaments at a preselcted resistance and temperature. In the presence of a gas containing combustibles, the catalyst on the detector filament (32) promotes combustion of the gas thereby increasing the temperature and resistance of the detector filament (32) to unbalance the detector bridge (12) and vary the magnitude of the output signal to the feedback control circuit (56). An operational amplifier (80) of the control circuit (56) is thus actuated at a reduced operating level to switch a transistor (TRI), connected to the power source (20) and an input (44) to the detector bridge (12), from a conductive state to a nonconductive state to thereby adjust the voltage level applied to the detector bridge. The bridge (12) is returned to a balanced condition, and the detector filament (32) is returned to its initial temperature. The variation in the voltage supplied to the detector bridge (12) is proportional to the concentration of combustibles present in the gas. The readout of the galvanometer (76) provides a quantitative measurement of the combustibles in the gas. Adjusting the voltage applied to the detector bridge (12) maintains the detector filament (32) at a constant temperature to increase the operating life of the detector filament and reduce evaporation of the catalyst on the filament.
Inventors
- 👤 Emilio G. Meyer
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 03:24
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/14; G01N27/16
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
171 words
A method of measuring the amount of combustibles present in a gas, comprising exposing the gas to a detector means (12) and a reference means (14), supplying a preselected input signal to the detector means (12) and to the reference means (14), and generating from the detector means (12) an output signal proportional to the amount of combustibles present in the gas, characterised by the steps of generating from the reference means (14) a regulated output signal, feeding back the output signal from the detector means (12) to a switching means (70), adjusting the magnitude of the input signal to the detector means (12)in response to the magnitude of the output signal fed back to the switching means (70) to restore the power supplied to the detector means (12) to a preselected magnitude, and measuring the magnitude of the adjusted input signal to the detector means (12) in comparison to the regulated output signal of the reference means (14) to indicate a quantitative measurement of the combustibles present in the gas.
Claim 2
Independent Claim
171 words
A method of measuring the amount of combustibles present in a gas, comprising exposing the gas to a detector means (12) and a reference means (14), supplying a preselected input signal to the detector means (12) and to the reference means (14), and generating from the detector means (12) an output signal proportional to the amount of combustibles present in the gas, characterised by the steps of generating from the reference means (14) a regulated output signal, feeding back the output signal from the detector means (12) to a switching means (70), adjusting the magnitude of the input signal to the detector means (12)in response to the magnitude of the output signal fed back to the switching means (70) to restore the power supplied to the detector means (12) to a preselected magnitude, and measuring the magnitude of the adjusted input signal to the detector means (12) in comparison to the regulated output signal of the reference means (14) to indicate a quantitative measurement of the combustibles present in the gas.
Claim 3
Dependent Claim
103 words
A method according to claim 1, which includes initially balancing the output signals of the detector means (12) and the reference means (14) in response to the gas being free of combustibles, detecting an unbalanced condition between the output signals of the detector means (12) and the reference means (14), adjusting the magnitude of the input signal to the detector means (12) to restore the detector means (12) to a balanced condition with the reference means (14), and measuring the combustibles present in the gas in proportion to the magnitude of the adjustment made to the input signal to the detector means (12).
Claim 4
Dependent Claim
41 words
A method according to claim 1, which includes controlling the rate of adjusting the magnitude of the input signal to the detector means (12) to provide a preselected signal proportional in magnitude to the concentration of combustibles present in the gas.
Claim 5
Dependent Claim
82 words
A method according to claim 1, which includes supplying the preselected input signal through the switching means (70) to the detector means (12), switching the switching means (70) between a conductive state and a non-conductive state in response to the magnitude of the feedback signal received from the output of the detector means (12), and thereby controlling the magnitude of the input signal supplied to the detector means (12) to maintain operation of the detector means (12). at a preselected voltage level.
Claim 6
Dependent Claim
120 words
A method according to claim 1, which includes exposing a catalytic coated detector filament (32) of the detector means (12) to the gas being measured, applying initially a voltage at a preselected level to the detector filament (32), increasing the temperature of the detector filament (32) by the burning of combustibles in the gas on the surface of the detector filament, changing the magnitude of the output signal from the detector means (12) in response to the burning of the combustibles in the gas on the surface of the detector filament, and adjusting the voltage applied to the detector means (12) to adjust the voltage applied to the detector filament and thereby maintain the detector filament at a preselected temperature.
Claim 7
Dependent Claim
41 words
A method according to claim 5, which includes measuring the concentration of combustibles in the gas expressed in terms of the adjustment to the voltage applied to the detector means (12) for maintaining the detector filament (32) at a preselected temperature.
Claim 8
Independent Claim
100 words
A method according to any one of claims 1 to 6, which includes feeding back an output signal from the reference means (14) to a switching means (72), adjusting the magnitude of the input signal to the reference means (14) in response to the magnitude of the output signal by switching the switching means (72) between a conductive state and a nonconductive state, and maintaining the voltage applied to the reference means (14) at a preselected level by switching of the switching means (72) to increase or decrease the magnitude of the input signal supplied to the reference means (14).
Claim 9
Dependent Claim
95 words
. A method according to claim 1, which includes actuating the switching means (70) between a conductive state and a non-conductive state to adjust the voltage applied to the detector means (12), maintaining a catalytic coated detector filament (32) of the detector means (12) at a preselected temperature, and recording the variation in the voltage applied to the detector means (12) when the switching means (70) is actuated for maintaining the detector filament (32) at a preselected temperature to thereby provide a quantitative electrical measurement of the concentration of the combustibles present in the gas.
Claim 10
Dependent Claim
106 words
A method according to claim 1, which includes actuating an amplifier means (80) in response to a change in the magnitude of the output signal of the detector means (12), generating a feedback signal by the amplifier means (80) to the switching means (70), actuating the switching means (70) in response to the magnitude of the feedback signal to regulate the voltage applied to the detector means (12) for maintaining the detector means in a balanced voltage condition, and measuring the concentration of combustibles present in the gas in terms of the regulated voltage applied to the detector means (12) for maintaining the balanced voltage condition.
Claim 11
Independent Claim
86 words
A method according to any one of claims 1 to 9, which includes operating the detector means (12) in a balanced condition at a first voltage level, operating the reference means (14) in a balanced condition at a second voltage level, and adjusting the output signal of a selected one of the detector means (12) and the reference means (14) so that under conditions for a gas free of combustibles the respective output signals are equal to provide a readout indicating zero combustibles in the gas..
Claim 12
Dependent Claim
256 words
Apparatus for measuring the amount of combustibles present in a gas, comprising detector means (12) for detecting the presence of combustibles in the gas, the detector means (12) having an input terminal (44) for receiving a preselected input signal and an output terminal (48) for supplying an output signal proportional to the amount of combustibles in the gas, reference means (14) arranged for exposure to the gas, and a power source (20) for supplying a preselected input signal to the input terminal (44) of the detector means (12) to operate the detector means at a preselected voltage level, characterised in that a feedback control circuit (56) is connected between the output terminal (48) of the detector means (12)and the input terminal (44) of the detector means, the feedback control circuit (56) includes a power switching means (70) for controlling the level of the input signal to the detector means input terminal (44) in response to the level of the output signal from the detector means (12) to restore the output signal to a preselected level, the reference means (14) is operative to generate a regulated output signal and is connected to receive a regulated input signal from the power source (20), and meter means (76) is connected to the detector means (12) and the reference means (14) for recording the difference in magnitude between the adjusted input signal to the detector means (12) and the regulated input signal to the reference means (14) as a quantitative measurement of the amount of combustibles present in the gas.
Claim 13
Dependent Claim
256 words
Apparatus for measuring the amount of combustibles present in a gas, comprising detector means (12) for detecting the presence of combustibles in the gas, the detector means (12) having an input terminal (44) for receiving a preselected input signal and an output terminal (48) for supplying an output signal proportional to the amount of combustibles in the gas, reference means (14) arranged for exposure to the gas, and a power source (20) for supplying a preselected input signal to the input terminal (44) of the detector means (12) to operate the detector means at a preselected voltage level, characterised in that a feedback control circuit (56) is connected between the output terminal (48) of the detector means (12)and the input terminal (44) of the detector means, the feedback control circuit (56) includes a power switching means (70) for controlling the level of the input signal to the detector means input terminal (44) in response to the level of the output signal from the detector means (12) to restore the output signal to a preselected level, the reference means (14) is operative to generate a regulated output signal and is connected to receive a regulated input signal from the power source (20), and meter means (76) is connected to the detector means (12) and the reference means (14) for recording the difference in magnitude between the adjusted input signal to the detector means (12) and the regulated input signal to the reference means (14) as a quantitative measurement of the amount of combustibles present in the gas.
Claim 14
Dependent Claim
83 words
Apparatus according to claim 11, which includes amplifier means (80) connected to the output terminal (48) of the detector means (12) for receiving the output signal of the detector means, the amplifier means (80) being operable in response to the output signal of the detector means (12) to actuate the power switching means (70) between a conductive state and a nonconductive state to thereby adjust the voltage supplied to the detector means (12) to maintain the detector means at a preselected voltage level.
Claim 15
Dependent Claim
45 words
Apparatus according to claim 11 or claim 12, which includes voltage storage means (92) associated with the power switching means (70) for controlling the rate of change in the voltage supplied to the detector means input terminal (44) from the power switching means (70). 1
Claim 16
Dependent Claim
129 words
Apparatus according to claim 11, claim 12 or claim 13, wherein the meter means (76) is operable to receive the adjusted input signal of the detector means (12) at a preselected magnitude, the meter means (76) is operable to receive the regulated input signal of the reference means (14) at a preselected magnitude, said adjusted input signal and said regulated input signal being unequal in magnitude for a gas free of combustibles, and a voltage adjustment means (102) is arranged to receive a selected one of said adjusted input signal and said regulated output signal to adjust said selected input signal to a magnitude corresponding to the other of said input signals to provide the meter means (76) with an initial zero reading for a gas free of combustibles.
Claim 17
Dependent Claim
100 words
Apparatus according to claim 11, which includes an amplifier (80) positioned in the feedback control circuit (56), the amplifier being operable to receive the output signal of the detector means (12) and to generate a corresponding feedback signal to the power switching means (70), the feedback signal from the amplifier (80) being proportional to the concentration of the combustibles in the gas and operable to actuate the power switching means (70) between a conductive state and a nonconductive state and thereby adjust the input signal to the detector means (12) for maintaining the detector means at a preselected voltage level.
Claim 18
Dependent Claim
158 words
Apparatus according to any one of claims 11 to 15, in which the detector means (12) includes a balanced bridge circuit having a detector filament (32) arranged to be exposed to the gas being measured, the detector filament (32) being coated with a catalytic material, the reference means (14) includes a balanced bridge circuit having a reference filament (40) arranged to be exposed to the gas being measured, the power switching means (70) is operable to adjust the voltage level of the input signal applied to the detector filament (32) to maintain the detector filament at a preselected temperature, and the meter means (76) is arranged to receive the adjusted input signal from the power switching means (70) and the regulated input signal to the reference means (14) and provide a quantitative readout of the combustibles concentration in the gas as expressed by the adjusted input signal required to maintain the detector filament (32) at a preselected temperature.
Claim 19
Dependent Claim
131 words
Apparatus according to claim 11, which includes an amplifier (80) for receiving the output signal from the detector means (12), the amplifier being actuable in response to the detector means output signal to transmit a corresponding signal through the feedback control circuit (56), the power switching means (70) being switchable between a conductive state and a nonconductive state in response to the signal from the amplifier (80) to control the voltage applied to the detector means (12) at a preselected level, and the meter means (76) being arranged to receive the adjustments in voltage applied to the detector means (12) by operation of the power switching means (70) and provide a quantitative readout indicating the combustibles concentration which is proportional to the adjustments in the voltage to the detector means (12).
Claim 20
Dependent Claim
44 words
Apparatus according to claim 11, in which the power switching means (70) includes a transistor (TR1) operable between a conductive state and a nonconductive state to adjust the voltage applied to the detector means (12) to maintain the applied voltage at a preselected level.
Claim 21
Dependent Claim
72 words
Apparatus according to any one of claims 11 to 18, which includes a feedback control circuit (68) connected between an output terminal and an input terminal of the reference means (14), the feedback control circuit (68) including a power switching means (72) for regulating the voltage applied to the reference means (14) to maintain the reference means at a preselected voltage with respect to the voltage applied to the detector means (12).
Claim 22
Dependent Claim
93 words
Apparatus according to any one of claims 11 to 19, wherein the detector means (12) and the reference means (14) can be arranged to operate at voltages of unequal magnitude, the detector means (12) and the reference means (14) being operable to generate output signals of unequal magnitude, and voltage adjustment means (102) is provided for adjusting a selected one of said output signals so that said output signals are of equal magnitude to provide the meter means (76) with an initial signal indicating the absence of combustibles in the gas being measured.
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