CN202916258U - Calibration device for gas sensor - Google Patents
Calibration device for gas sensor Download PDFInfo
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- CN202916258U CN202916258U CN 201220605035 CN201220605035U CN202916258U CN 202916258 U CN202916258 U CN 202916258U CN 201220605035 CN201220605035 CN 201220605035 CN 201220605035 U CN201220605035 U CN 201220605035U CN 202916258 U CN202916258 U CN 202916258U
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Abstract
A calibration device for a gas sensor consists of a gas concentration regulation module and a gas sensor detection module which are connected in series, and is characterized in that in the gas concentration regulation module, a gas chamber, valves, a gas pump and a gas quantitative regulator form a circulating gas passage; after the gas pump and the gas quantitative regulator are connected in series, the two ends are connected with the gas chamber through two of the valves; and the other two ports of the gas chamber are respectively connected with the gas sensor detection module and a sample gas through the other two valves.
Description
Technical field
The present invention relates to the caliberating device of gas sensor.
Background technology
What material concentration is measured general using with sensor is incidence relation between sensor response and test substance concentration.And the zero point of sensor and sensitivity in use can be drifted about inevitably.In order to obtain more accurately measured value, before generally all requiring to measure sensor is demarcated.(as less demanding to accuracy of measurement, then in the certain error allowed band, can suitably relax spot frequency.)
Demarcation need to be measured sensor with the standard substance of concentration known, and for liquid, solid matter, the acquisition of standard substance concentration is relatively easy, generally passes through the analytical balance weighing in the laboratory, and the volumetric flask constant volume just can be accomplished.And the acquisition of the calibrating gas of low concentration is bothered relatively, generally all need by buying to the calibrating gas supplier who obtains China Metrology Accreditation.
Calibrating gas supplier is the weight method preparing calibrating gas of adopting international standards tissue recommendation generally, to the gas of low concentration owing to there being the problem such as adsorption equilibrium, need calibration check before dispatching from the factory, the conventional method of its check is gas chromatographic technique, and gas chromatography also needs the calibrating gas of higher level to demarcate, the problem that propagation of error is arranged here, in addition, calibrating gas dispatches from the factory rear because absorption, the factors such as infiltration can make its concentration continue to change, and the client is difficult for discovering to this variation.Non-type with this such as the client " Standard Gases " calibrated sensor measures inaccurate beyond doubt.
Even the demarcation to sensor is accurately, if sensor large (humiture and interference gas etc.) affected by environment, the difference of condition also can be introduced larger error during measurement and calibration.A method of dealing with problems is the characteristics according to sensor, temperature to sensor, humidity, the Characteristic Compensation of Medical Sensors such as pressure, the method can improve the accuracy of sensor measurement within the specific limits, but to the consistance of sensor performance, have relatively high expectations (prerequisite of compensation is that the above-mentioned characteristic of sensor does not change with environmental evolution in time) of stability.
Chemical analysis method can provide a kind of absolute measurement standard, but in order to obtain accurately the often a large amount of gas of needs of analysis result, even can exhaust whole bottle gas, is there there simpler absolute standard method?
US Patent No. 4829809 (Citytech 1989) has disclosed a kind of gas electrolytic analysis apparatus and method, it places an electrochemical sensor cavity of known volume, at first pass into the gas to be measured of unknown concentration in the cavity, timing signal seals cavity, owing to sensor consumes gas its response is constantly reduced, according to the Farady law, its electric current is decayed with exponential form, according to sensor current temporal evolution curve, sensor initial response electric current, cavity volume can be found the solution transducer sensitivity and gas concentration.But the value of this patent has been to provide a kind of just method of measure gas concentrations of transducer sensitivity that need not to know, but the method that this patent adopts is that gas in the cavity is carried out electroanalysis, the gas incomplete mixing can cause larger measuring error in the cavity, in addition, owing to employing in computation process is transient current, very high to the sensor signal quality requirements, very little measurement current error all can cause larger calculation deviation, thereby is not suitable for the light concentration gas detection.In fact, the method is not used at large.
US Patent No. 4833909 (Dragger, 1989) has been described a kind of similar coulometry device.
US Patent No. 6055840 (Industrial Scientific corporation, 2000) a kind of method of finding the solution gas concentration by quantitative adjusting control gas diffusion paths resistance has been described, the method need to be known the coefficient of diffusion of gas to be measured and the physical size of at least one gas diffusion paths, thereby practical application is also inconvenient.
Honeywell discloses the patent (US7975525B2 of multinomial transducer calibration and self-calibrating method recent years, US7661290B2, US2006/0266097A1, US2005/0262924A1, US7401493B2, US7581425B2, US7655186B2, US7071386B2, US6918281, US2006/0042351A1), Drager also discloses several transducer calibration patent (US7704356B2 recently, US7645362B2), a common ground of these patents is exactly that they all need calibrating gas, and the method that just produces calibrating gas is had nothing in common with each other.Integrate electrochemical gas generator such as US7645362B2, US7645362B2, US2005/0262924A1 in gas circuit or sensor; US7975525B2 connects a gas concentration modulating device and is used for gas pre-concentration and analytic signal modulation (carrying out the baseline correction) in gas circuit, gas circuit connects standard gas generating apparatus for Demarcate Gas simultaneously; US7661290B2 is stored in calibrating gas in the one parcel mounted box, is convenient to rolling and carries, and timing signal punctures packing and is used for transducer calibration etc. in the cavity that releases the gas into fixed volume.
Summary of the invention
The deficiency that the present invention is directed to present technology has proposed a kind of device and method that sensor is carried out on-site proving.It thes contents are as follows:
This device is composed in series by gas concentration adjusting module and gas sensor detection module, described gas concentration adjusting module is by air chamber, valve, air pump, the gasometry adjuster forms the circulation gas circuit, air pump is connected with air chamber by valve with the rear two ends of gasometry adjuster series connection, and two other port of described air chamber connects gas sensor detection module and sample gas by valve respectively.
A kind of gasometry adjuster is electrochemical cell described in the said apparatus, and the quantitative electrolysis of described electrochemical cell gas to be measured is by electrolysis electricity control gas concentration variable quantity.
Another kind of gasometry adjuster described in the said apparatus is controlled the gas concentration variable quantity for for gas to be measured occurs in the electrochemical gas generator electrolysis by the Electrochemical generation electric weight.
Above-mentioned air chamber is comprised of elongate conduit, and the vertical two ends of pipeline are connected with sample gas with the gas sensor detection module by valve, and described elongate conduit laterally is connected with valve in the described gas concentration adjusting module respectively by capillary array.
Above-mentioned air chamber also can be the air chamber of elongate conduit and moveable piston.
The present invention has disclosed a kind of device and method that directly sensor is carried out on-site proving with sample gas, has overcome the impact of sensor signal drift, humiture and part interference gas, thereby improves the Stability and dependability of measuring; Adopt the electrochemical electrolysis method to produce or consume tested gas, by the amount that electric weight control produced or consumed gas, method is easy to be controlled, has improved the convenience that device uses.
Description of drawings
Fig. 1: sensor calibration apparatus gas circuit structure schematic diagram of the present invention
Specific embodiment
Embodiment one
How the present embodiment is demarcated sensor with apparatus of the present invention to introduce in conjunction with Fig. 1.
This device is composed in series by gas concentration adjusting module and gas sensor detection module, it is characterized in that: described gas concentration adjusting module 500 is by air chamber 101, valve 401, valve 402, valve 403, valve 404, air pump 301, gasometry adjuster 201 forms the circulation gas circuit, air pump 301 is connected with air chamber 101 by valve 403,404 with the rear two ends of gasometry adjuster 201 series connection, and described air chamber 101 two other ports connect gas sensor detection module 600 and sample gas by valve 401,402 respectively.Described gas sensor detection module 600 is comprised of air pump 302 and sensor 202 in the present embodiment, according to circumstances also can be without air pump when practical application.
The adjuster 201 of gasometry described in this example and sensor 202 are the galvanochemistry nitric oxide sensor, and the air chamber volume is 30ml, measure demarcation with 75ppb nitrogen monoxide gas and characteristics of contaminated respiratory droplets gas respectively.The measurement calibration process is as follows
1) sensor 202 access devices to be calibrated are connected with air pump 302, open valve 401,402, enter air chamber 101 by pump 302 draw samples gas, the steady-state response electric current of record sensor 202, relation is satisfied in the response of this sensor:
S
1=kC=0.165（uA） （1）
S wherein
1For sensor response, k are that transducer sensitivity, C are gas concentration
2) valve-off 401,402 is opened valve 403,404, makes gas get back to air chamber 101 behind air chamber 101, valve 403, gasometry adjuster 201, air pump 301, valve 404 by air pump.In this cyclic process, the gasometry adjuster carries out electrolysis to the gas in the air chamber and causes its concentration to descend, and this process satisfies relation:
Q=∫i
201dt?=nFV*△C=4.95(uC) （2）
Wherein Q is that electrolytic cell 201 Faradaic currents, t are that cyclic electrolysis time, n are that Faraday constant, V are that air chamber volume, △ C are the variable quantity that electrolysis causes gas concentration for response consumes power, i201.
3) open valve 401,402, enter sensor 202 by the gas in the pump 302 extraction gas air chambers 101 and carry out double measurement, the steady-state response electric current of record sensor 202, relation is satisfied in the response of this sensor:
S
2=k(C-△C)=0.123（uA） （3）
Can be tried to achieve by equation (1) ~ (3) simultaneous:
k=nFV(S1-S2)/∫i
201dt?
=2.21(nA/ppb) （4）
C=?S
1/(S1-S2)
*∫i
201dt/(nFV)=75.2(ppb) （5）
The transducer sensitivity that said method is tried to achieve is 2.2nA/ppb, coincide with the sensitivity that directly calculates with Standard Gases (formula (1)).
With the characteristics of contaminated respiratory droplets gas collection in the Tedlar airbag, it is 2.25nA/ppb that repetition above-mentioned steps (1), (2), (3) calculate 202 pairs of nitric oxide production sensitivity of sensor, mouth expiration nitric oxide concentration is 16.7ppb, sensitivity and Standard Gases test result approach, mouthful breath tester result also with the test result 17.2ppb of the NIOX of Sweden Aerocrine company without significant difference.
This shows, said apparatus and method can be in the situation that when not needing calibrating gas to determine the sensitivity of sensor 202, also can measure sample gas concentration.
The method is on-the-spot demarcates with gaseous sample to be measured, can overcome to greatest extent the impact of humiture, interference gas and sensor signal drift, has improved accuracy and the reliability measured.
Above principle of work and the process that this device has been described by the example of demarcating by nitric oxide sensor, by principle as can be known, as long as response equation (1) is satisfied in the response of sensor, process (2) can be set up mass equation (2), carrying out double measurement by step (3) just can demarcate the sensitivity of sensor 202, and to not restriction of sensor type, can be electrochemical sensor, semiconductor transducer, catalytic combustion sensor, infrared sensor etc.
What easily expect is that by controlling the different cyclic electrolysis time, the gas that can produce different varied concentrations is used for demarcating, and by the system of equations that a plurality of mass equations and measurement equation form, finishes the demarcation to the nonlinear transducer parameter by construction.
This installs preferred a kind of air chamber structure and has following characteristics: air chamber is comprised of elongate conduit, the vertical two ends of pipeline are connected with sample gas with the gas sensor detection module by valve, and described elongate conduit laterally is connected with valve in the described gas concentration adjusting module respectively by capillary array.When carrying out analysis to measure, gas has suffered to flow in elongate conduit and has been piston flow, and not blend of gas before and after guaranteeing is when carrying out the concentration adjustment, gas in time upgrades the gas in the air chamber fast by the horizontal capillary array of pipeline, guarantees the homogeneity that gas concentration distributes in the air chamber.
This device air chamber also can be comprised of the air chamber of moveable piston, and when gas circulated through air chamber at every turn when concentration is adjusted, gas concentration can mix rapidly in the air chamber, promotes gas flow by piston during analysis to measure and measures demarcation through sensor.
Same thinking, electrochemical cell does not carry out electrolysis to sample gas if concentration regulating module is not sampled, and can reach the purpose that gas concentration changes in the quantitative control air chamber and with electrochemical gas generator sample gas occurs quantitatively yet.
Equally, concentration measurements and substances in liquids measurement of concetration are also different without essence in the gas, are applicable to thereby said method and device also are applicable to the measurement of substances in liquids concentration.
Claims (5)
1. gas sensor calibration device, be composed in series by gas concentration adjusting module and gas sensor detection module, it is characterized in that: described gas concentration adjusting module is by air chamber, valve, air pump, the gasometry adjuster forms the circulation gas circuit, air pump is connected with air chamber by valve with the rear two ends of gasometry adjuster series connection, and two other port of described air chamber connects gas sensor detection module and sample gas by valve respectively.
2. a kind of gas sensor calibration device as claimed in claim 1 is characterized in that wherein said gasometry adjuster is electrochemical cell, and the quantitative electrolysis of described electrochemical cell gas to be measured is by electrolysis electricity control gas concentration variable quantity.
3. a kind of gas sensor calibration device as claimed in claim 1 is characterized in that wherein said gasometry adjuster is that gas to be measured occurs in the electrochemical gas generator electrolysis, by electrochemical gas generation electric weight control gas concentration variable quantity.
4. a kind of gas sensor calibration device as claimed in claim 1, it is characterized in that wherein said air chamber is comprised of elongate conduit, the vertical two ends of pipeline are connected with sample gas with the gas sensor detection module by valve, and described elongate conduit laterally is connected with valve in the described gas concentration adjusting module respectively by capillary array.
5. a kind of gas sensor calibration device as claimed in claim 1 is characterized in that wherein said air chamber is the air chamber of moveable piston.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220605035 CN202916258U (en) | 2012-08-07 | 2012-11-16 | Calibration device for gas sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201220387546 | 2012-08-07 | ||
| CN201220387546.3 | 2012-08-07 | ||
| CN 201220605035 CN202916258U (en) | 2012-08-07 | 2012-11-16 | Calibration device for gas sensor |
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| CN202916258U true CN202916258U (en) | 2013-05-01 |
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| CN 201220605035 Expired - Lifetime CN202916258U (en) | 2012-08-07 | 2012-11-16 | Calibration device for gas sensor |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105486811A (en) * | 2015-12-22 | 2016-04-13 | 东南大学 | Device and method for testing rapid response characteristic of gas sensor |
| CN105527374A (en) * | 2014-10-24 | 2016-04-27 | 霍尼韦尔国际公司 | Automatic calibration system and gas supply method thereof |
-
2012
- 2012-11-16 CN CN 201220605035 patent/CN202916258U/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105527374A (en) * | 2014-10-24 | 2016-04-27 | 霍尼韦尔国际公司 | Automatic calibration system and gas supply method thereof |
| CN105486811A (en) * | 2015-12-22 | 2016-04-13 | 东南大学 | Device and method for testing rapid response characteristic of gas sensor |
| CN105486811B (en) * | 2015-12-22 | 2017-10-20 | 东南大学 | Test device and method of testing for gas sensing device fast response characteristic |
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Granted publication date: 20130501 |