FR2806163A1 - Continuously operating analyzer for volatile organic compounds to monitor air quality - Google Patents

Abstract

An analyzer contains a measuring module with a carbon monoxide (CO)/organic volatile compound (VOC) detector (15) and a water detector (16). A control valve (13) operated by a sequencer (14) commutes the flow between two parallel branches of an air treatment circuit, with a cartridge which selectively retains VOCs mounted on a first branch (12) and a second, direct branch. An analyzer contains a measuring module with a carbon monoxide (CO)/organic volatile compound (VOC) detector (15) and a water detector (16). A control valve (13) operated by a sequencer (14) commutes the flow between two parallel branches of an air treatment circuit, with a cartridge which selectively retains VOCs mounted on a first branch (12) and a second, direct branch. A pump (17) operates downstream of the detectors so the air to be analyzed is drawn through a filter (11) to the detectors either directly or after passing through the cartridge. The analyzer also contains a treatment circuit for the signals from the detectors and the sequencer to determine the water content of the air, the CO content of an air sample free of VOC and the VOC content derived from the difference in signals from the CO/VOC detector depending on the route the sample took. Independent claims are also included for the following: (i) a device for measuring the quality of ambient air, comprising the above device with the addition of nitrogen dioxide (NO2) and carbon dioxide (CO2) detectors (20, 21) upstream of the VOC and water detectors, where the NO2, VOC and water detectors are all metal oxide chemical micro-detectors and the pump is a membrane pump; and (ii) a process for operating the above device by calibrating each detector, calculating the correction due to the influence of majority component interference, transposing the output signal for each detector taking into consideration the calibration and correction, determining a quality index for each component by referring to an evaluation chart giving different threshold values and thus obtaining a global quality index as a function of the component indices obtained.

Description

 CONTINUOUS <B> ANALYZER OF VOLATILE ORGANIC COMPOUNDS, <B> DEVICE AND </ B> METHOD OF <B> CONTINUOUS <B> QUALITY <B> AIR QUALITY </ B > INTERIOR AMBIENT <B> AND USE OF THIS </ B> <B> DEVICE FOR THE CONTROL OF A VENTILATION </ B> INSTALLATION <B> DESCRIPTION </ B> <B> DOMAIN </ B> TECHNIQUE The present The invention relates to a continuous analyzer for volatile organic compounds (VOC), a device and a method for continuously evaluating the quality of the indoor ambient air and a device for controlling a ventilation installation. <B> STATUS OF THE </ B> PRIOR TECHNIQUE Different parameters are likely to characterize the quality of the indoor ambient air and in particular the contents of H20, C02, C0, NOx and VOC. If we successively analyze each of these compounds we have.

 H20: Humidity and water content are recognized comfort factors. They are also indicators of human presence such as C02, but much less precise given the great variability of the natural moisture content of the air, and the low emissions related to human presence compared to the high levels of air ambient. C02: Carbon dioxide is not really considered a pollutant, but it is an excellent indicator of human presence in tertiary sector premises. It is also a good indicator of poor ventilation in living quarters especially when using cooking appliances or auxiliary heating.

CO: Carbon monoxide is a pollutant whose presence inside the premises of the tertiary sector mainly due to the inflow of polluted outside air, to a defective combustion or to smoke of tobacco. In living quarters it is responsible for a considerable number of fatal accidents each year due to defective combustion equipment, or not connected to smoke evacuation ducts.

 NOx: Nitrogen oxides can be represented as NO2 dioxide, which is the most harmful and the only one affected by the regulation of outdoor ambient air. In the premises of the tertiary sector, the presence of NOx is essentially due to the inflow of polluted outside air.

Volatile organic compounds include a considerable number of compounds whose harmfulness is highly variable. Of these, formaldehyde (HCHO) is chosen as an indicator; it is a product of degradation of materials, frequently emitted inside premises, irritating mucous membranes and whose long-term toxicity is now recognized.

These different compounds can be used to establish an "index" of air quality. However, it is excluded, mainly for cost reasons, to use specific analyzers with high metrological performance. Indeed, a semi-quantitative determination with good reliability is acceptable.

The invention therefore firstly for and a continuous analyzer of volatile compounds. It also relates to a device and a method for continuous evaluation of indoor air quality, compact, easy to use and maintenance, moderate cost, and able to restore a quality index of air defined from the contents of pollutants and their relative harmfulness; to reliably and selectively quantify the five compounds defined above, in real time using commercial micro-sensors. The present invention relates to a continuous analyzer for volatile organic compounds, characterized in that it comprises a measuring module comprising sensitive elements of H20 and CO / VOC sensors, a circuit for sequential treatment of the air, a module for processing and operating the output signals of these sensors, and in that the sequential treatment circuit the air is such that this air is sucked by a pump. Through a dust filter and scans the first H20 sensor and the second CO / VOC sensor, either directly through a first channel, or after passing through an organic species retention cartridge through a second way; the switching on one or other of these two channels being provided by a solenoid valve controlled by a sequencer. The present invention also relates to a device for continuous evaluation of the indoor ambient air quality comprising such a continuous analyzer of volatile compounds, in which the measurement module also comprises the sensing elements of NO 2 and CO 2 sensors, and wherein the sequential treatment circuit of the air sucked by the pump through the dust filter first scans the third NO2 sensor and the fourth CO2 sensor before being transferred to the first H2O sensor and the second CO / VOC sensor through the first or second lane.

Advantageously, the first, the second and the third sensors are chemical microsensors with metal oxides. The pump is a diaphragm pump.

The present invention also relates to a method of continuous evaluation of indoor air quality using the above device and which comprises the following steps.

the calibration curve of each of the measuring sensors of the various compounds H20, CO / COV, NO2 and CO2 is determined, the influence of the majority interfering compounds is calculated by calculation, the output signal of each sensor is transposed into measured compound content, taking into account its calibration curve, - a quality index is determined for each compound measured by referring to an evaluation grid which gives an index value for each compound according to different thresholds of compound contents referring to health data, - one obtains an overall index of the quality of the 'according to the various composite indices obtained.

The preceding device can be advantageously used for controlling a ventilation installation.

 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates the device of the invention.

FIG. 2 illustrates the response curve of the sensor 20.

Figure 3 illustrates the calibration curve of the sensor 16.

Figure 4 illustrates a measurement sequence.

FIG. 5 illustrates the exploitation of the output signals of the sensors 15 and 16. <B> DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS </ B> As illustrated in FIG. 1, the continuous analyzer of volatile organic compounds 10 comprises successively a filter 11, which may be a coarse dust filter, a cartridge 12 for selectively retaining volatile organic compounds disposed on channel 2 in parallel with a direct channel 1, a solenoid valve 13 controlled by a sequencer 14, which provides 1-way channel switching 2, - a first CO / VOC sensor 15 and a second H20 sensor 16, - a pump 17 which may be a diaphragm pump, - a signal processing circuit 18 from the sensors 15 and 16 and the sequencer 14. The air to be analyzed is sucked by the pump 17 through the filter 11 and is transferred to the sensors CO / VOC 15 and H20 16, either directly or after passing through the cartridge. sequential action being provided by the solenoid valve 13.

The pump 17, which makes it possible to ensure the sampling of the air, is placed downstream of the analysis circuit so as to avoid any contamination or retention of species.

The analyzer of the invention therefore comprises two main parts - a measurement module, which comprises the sensitive elements of the CO / COV and H20 sensors 15 and 16, the supply and measurement circuits and a sequential processing circuit of sampled, - a module 18 for processing signal exploitation.

The device for continuously evaluating the quality of the indoor ambient air according to the invention illustrated in FIG. 1, comprises all the analyzer elements 10 of the invention, as defined above. I1 further comprises a third N02 sensor and a fourth CO2 sensor 21 disposed between filter 11 and lanes 1 and 2.

The method for continuously evaluating the quality of the indoor ambient air according to the invention implementing the device defined above comprises the following steps: the calibration curve of each of the sensors 15, 16, 20 is determined and 21 different measuring compounds: H20, CO / VOC, NO2 and CO2, - the influence of interfering majority compounds is calculated by calculation, - the output of each sensor is transposed into measured compound content, taking into account its curve. For calibration and majority interferants, a quality index is determined for each compound measured by reference to an evaluation grid, such as that shown by way of example in Table 3, which gives an index value for each compound. according to different thresholds of contents of compounds referring to sanitary data, - one obtains a global overall index of the quality of the air according to the different indices composed s thus obtained.

 EXAMPLE In one embodiment, the CO / COV, NO 2 and NO 2 sensors 15, 16 and 20 used are commercially available metal oxide chemical microsensors. type sensor consists of a semiconductor sensitive element, most often based on tin oxide Sn02, brought to its optimum operating temperature by means of a heating element, and whose electrical characteristics vary according to the presence in the ambient air of gaseous compounds.

The sensitive element is the seat of absorption-desorption and oxidation-reduction phenomena whose equilibrium is mainly determined by temperature. The electronics of such a sensor is very simple.

The C02 sensor 21 is an infrared (IR) sensor. Indeed, CO2 has the property of absorbing infrared radiation with an absorption maximum between 4000 nm and 4400 nm. For a given measurement cell geometry, the radiation absorption is directly related to the CO2 concentration (Beer-Lambert law). This sensor 21 could also be a chemical microsensor: Among the different types of possible sensors, the following sensors 15, 16, 20, 21 have been chosen, for example:

CO / COV <SEP>: <SEP> Sensor <SEP> FIGARO <SEP> TGS <SEP> 2620
<tb> sensor <SEP> FIGARO <SEP> TGS <SEP> 2180
<tb> N02 <SEP>: <SEP> Sensor <SEP> FIGARO <SEP> TGS <SEP> 2105
<tb> C02 <SEP>: <SEP> sensor <SEP> IR <SEP> SAUTER / type <SEP> EGQ220F001 The sensitive elements of the sensors 20 and 21 of NO2 and CO2 can be arranged on a support and be exposed directly to the ambient air sampled by the membrane pump.

The sensor 21 CO 2 is integral with its electronics and is used as provided by the supplier after being removed from protective housing for reasons of space.

The sensors 15 and 16 CO / VOC and H20 are arranged under a hood. allowing a sweeping alternately, either directly by the ambient air, or after passing through the cartridge 12.

Cartridge 12 for selectively retaining volatile organic compounds can be made using potassium permanganate.

Aldehydes, ketones, alcohols indeed, react with potassium permanganate and are stopped, by oxidation, in a quantitative manner; the benzene compounds are retained, a priori, by adsorption; The air flow to be purified must be low so as to ensure a sufficient contact time for complete trapping, in practice a flow rate of 0.3 l / min and a cartridge of 200 mm are usable. A lower flow rate reduces the size of the cartridge without affecting battery life. Activated aluminum oxide (Al 2 O 3 alumina) in microporous beads 2 mm in diameter is used as a carrier for the active compound consisting of potassium permanganate (KMnO 4). To obtain a preparation for 100 g, very simply carries out the immersion impregnation of 100 g of alumina in an acidified aqueous solution (H2SO4 10-2N) at 60 g / l of potassium permanganate. After wringing, the alumina balls are dried at 60-70 ° C. for approximately 4 hours and stored under air, this treatment makes it possible to obtain an alumina containing 5% by weight of KMnO 4. 100 g of this preparation make it possible to fill 6 cartridges of 200 mm / diameter 20 mm.

The pump 17 may be a WISA type diaphragm pump used in gas analyzers, separated from the sensors for reasons of space; but it can also be a pump of smaller size which can be easily arranged in the measuring case.

The duration of the control signal cycle of the solenoid valve 13, supplied by the sequencer 14, can be chosen between 30 seconds and three hours, for example 5 minutes.

The circuit 18 for processing the output signals delivered by the sensors 15, 16, 20, 21 is produced using an acquisition unit AOIP 70 I channels coupled to a PC type computer; the mathematical processing of the signals is done using EXCEL software. It is also possible to use microprocessors integrated in the device of the invention.

In this embodiment, the following measurements were made.

<U> Measurement of Nitrogen Dioxide </ U> (NO 2) The measurement is made by exposing the NO 2 sensor to the sampled air stream.

As illustrated in FIG. 2, the sensor 20 offers a response to nitrogen dioxide in a relatively narrow concentration range (0 to 200 ppb), but adapted to the levels encountered in the premises under consideration, with a fairly good selectivity that allows direct exploitation. of the signal.

The impact of NO2 measurement, effective for high CO / NO2 concentration ratios (greater than), could be neglected without significant errors.

<U> Moisture Measurement </ U> (H20) The measurement is made by the sensor 16 which offers good sensitivity and good selectivity to water, its response is related to the water content (expressed in mass / m3 or ppm), and not the relative humidity of the air C0, CO2, NOx and VOCs have no influence on the measurement in the areas concerned by ambient air.

The response of this sensor 16, illustrated in FIG. 3, is used both for measuring the water content but also for correcting the influence of the latter on the response to and the VOC of the sensor 15.

<U> Associated measurements of C0, </ U> H20 <U> and </ U> VOC The contents of C0, H20 and VOC are measured using the two sensors 15 and 16.

The CO and Volatile Organic Compounds (VOC) contents are evaluated using the multi-pollutant sensor which offers good sensitivity to VOCs but requires a correction of 1 influence of the water content effected by the second specific sensor 16. some water.

Inside the premises, VOCs are present at very low concentrations with regard to the levels of potentially interfering compounds such as CO or H20 which make the corrections very purely mathematical. This difficulty is circumvented by performing a selective trapping VOCs using the cartridge 12, upstream of the sensor 15, and alternately admitting this sensor 15 purified air and air to be analyzed. The major interferers are not stopped the difference of the signals allowed to access with a good sensitivity to the VOC content. The areas concerned are as follows. H20: 5000 to 25000 ppm CO: 0 to 25 ppm Total VOC: a few tens of ppb '1 ppm. By operating by calculated differences on the stabilized signals during each sequence, it is possible to access the masked compound concentration while avoiding the interfering compound contents as well as zero drifts of the sensor.

The two associated sensors 15 and 16 thus make it possible, depending on the sampling period of the signal, to access the following three parameters with good accuracy - the water content of the ambient air, - the CO content of the air ambient on a sample cleared of VOCs, - the VOC content, operating by difference of the signals.

The air sampled by the pump 17 is thus admitted to the two sensors 15 and 16, either directly or after passing through the cartridge 12 as shown in FIG. 4. 5 minute sequences are chosen.

The raw signals delivered by these sensors and 16 are sampled after stabilization, in the following way lane 1 (ambient air) => sensor 16 => measurement of ambient H20, lane 2 (cartridge) = * sensor 15 = * measurement of ambient CO I cleared of trapped VOCs (1-way lane 2) = * measurement of trapped VOCs. The signal sampling phases are illustrated in Figure 5 showing a typical evolution of the signals during the test.

<U> CO2 measurement </ U> The measurement is performed using the sensor. This infrared sensor, without protection box, is integrated without modification of the device. This sensor has a good linearity of response in its measurement range (0 to 2 ppm), and a good sensitivity.

For processing the output signals of the sensors, the following calibration curves are considered <U> Nitrogen dioxide </ U> (NO2) / sensor <U> 20 </ U> The calibration curve is of type [N02 ] = aE, nl or: [N02] represents the concentration expressed in ppb E represents the sensor signal (in volts). <U> Water content </ U> (H20) / sensor <U> 16 "channel 1" </ U> The equation of the sensor calibration curve 16 is of the type H20in ppm = b. (E-Eo) 2 + C. (E-Eo) + from where. E represents the raw voltage delivered by the sensor (in Volts) and Eo represents the base voltage of the sensor. <U> carbon monoxide </ U> (CO) / sensor <U> 15 "lane 2" </ U> The equation of the sensor calibration curve with respect to CO is a second degree polynomial of type COen ppm = e. E-EO-E (H20) + 2 + f. [E-Eo-E (H20) 1 + g where E represents the raw voltage delivered sensor 0 (in volts), E0 represents the base voltage of the sensor, E (H20) represents the correction of the influence of the content in water on the sensor 15, from the content delivered by the sensor 16.

 Formaldehyde <U> and volatile organic compounds expressed </ U> <U> in "equivalents </ U> formaldehyde" / sensor <U> 15 "lane 1 - lane </ U> 2" Among the major VOCs in the air polluted environment, the cartridge 12 quantitatively stops the compounds and families of the following compounds - formaldehyde and other aldehydes, - ketones (acetone ...), - alcohols (methanol, ethanol ...), - benzene compounds.

All these compounds have a recognized toxicity and the sensor 15 presents them with comparable sensitivities. Among these pollutants, formaldehyde is predominant inside the premises and it is all of these "undesirable" VOCs that is expressed in "formaldehyde equivalents".

The CO (and the alkanes) present in the air at levels which can reach several ppm, is not stopped by the cartridge 12.

The toxic CO 2 is measured during the sequence corresponding to channel 2. The measurement of CO integrates the possible presence of alkanes. In case of presence of these compounds, the measurement is made by excess; this is an advantage in allowing the device to react to the presence of methane in case of natural gas leakage, for example.

For each response level the averages in lane 1 and lane 2 are calculated eliminating the stabilization phases (approximately 1 minute before and after each switching).

 # For the sensor 15 we have - Channel 2 (trapping). 0.5 [average (t0 + 7 to t0 + 9) + average (t0 + 17 to t0 + 19)] (average of sequence signals "channel 2" preceding and following a "channel 1" sequence) - channel 1 (passage direct). average (t0 + 12 to t0 + 14) # For sensor 16 on - Channel 2 (trapping): 0.5 x [average (to + 7 to t0 + 9) + average (to + 17 to + 19) ] (average signals from the "channel 2" sequences preceding and following a "channel 1" sequence) - channel 1 (direct passage): average (to + 12 to t0 + 14) The influence of the content variations on the sensor 15 is corrected very simply by affecting the deviation of the signals "channel 1-channel 2" measured on the sensor 16 of a coefficient S representing the respective water sensitivity ratio of these two sensors, that is to say the ratio of the slopes of the two response curves in a humidity range of 5000 to 25000 ppm.

The responses of the sensors 15 and 16 (differential raw voltages in volts) in the areas of extreme moisture content encountered in outdoor air is given in Table 1 at the end of the description. The equation of the curve of variation (assimilated to a straight line) of this ratio as a function of the water content is: Coefficient S = 2.10-5 [H20] The variations of water contents at the level of the sensor 15, downstream of the cartridge 12, are between 0 and + 6000 ppm; a fixed ratio of 1.67 is therefore retained between the raw voltages delivered by the sensors 15 and 16 for the same water content.

The value of 1.67 corresponding to the maximum water content deviation is preferentially retained at an average coefficient, since it allows a better correction adequacy insofar as only the high differences have a significant impact on the results. Thus, after correction of response to the water content of the VOC sensor (in mg / m 3 HCHO) = K1 x / (0 (V1-V2) 2620-1, 67 x 4 (V1 V2) 2180) where K1 is obtained is the slope of the response of the sensor 15 to the Si the second term makes it possible to correct response to the water of the sensor 15, the difference "lane 1-lane 2" of the first term makes it possible to correct the sensor response to the non-trapped CO the cartridge 12 to overcome any zero drifts of the sensor 15 over time.

Calibration is performed by injection and vaporization of known amounts of HCHO in 37% aqueous solution; Table 2 at the end of the description provides the values of the signals after treatment described above. The calibration curve is a line in a concentration range between 0 and 6 mg / m3. <U> Carbon Dioxide / Sensor 21 </ U> The equation of the calibration curve is CO2 in ppm = a x E + b where E is the signal expressed in volts (10 V for 0-2000 ppm).

 ESTABLISHING <B> AIR QUALITY <B> INDEX </ B> Various approaches for establishing such an index may be considered; one solution is to compare the measured content of each selected compound: H 2 O, CO, NO 2, HCHO, CO 2 at different thresholds as in the table 3 grid.

 The concentration levels likely to be reached by each of these levels are divided into 10 classes established from either regulatory thresholds where they exist or recommendations from the World Health Organization for the protection of health and constitute each elementary index.

The overall index is represented by the largest index of the elementary indices corresponding to each of the selected compounds.

An example of a CO index is the following: Regulatory limit in working environment: 50 ppm over 8 hours.

<SEP> WHO <SEP> recommendations: <SEP> 60 <SEP> mg / m3 <SEP> (= <SEP> 50 <SEP> ppm) <SEP> for <SEP> 30 <SEP> min
<tb> 30 <SEP> mg / m3 <SEP> (25 <SEP> ppm) <SEP> during <SEP> 1 <SEP> h
<tb> 10 <SEP> mg / m3 <SEP>(<SEP> 5 <SEP> ppm) <SEP> during <SEP> 8 <SEP> h

Maximum <SEP> retained
<tb> for <SEP> 1 <SEP> index <SEP> 20 <SEP> ppm <SEP> (23 <SEP> mg / m3 <SEP><B>,#-></B><SEP> index <SEP> 10 Similarly, an index of 10 corresponds to -1 mg / m 2 of COv expressed as HCHO equivalents (0.8 ppm to pg / m 3 of NO 2 (109 ppb at 20 ° C.) - 2000 ppm of CO 2 (3667 mg / m 2). m3)

Table <SEP> 1
<tb> H20 <SEP> in <SEP> m <SEP><U> Signal </ U><SEP> TGS <SEP> 2620 <SEP><U> Signal </ U><SEP> TGS <SEP> 2180 <SEP><U> report </ U>
<tb> 2500 <SEQ> 0.1938 <SEQ> 0.1194 <SEP> 1.623
<tb> 5000 <SEP> 0.3750 <SEP> 0.2275 <SEQ> 1.648
<tb> 6000 <SEQ> 0.4440 <SEQ> 0.2676 <SEQ> 1.659
<tb> 7000 <SEP> 0.5110 <SEP> 0.3059 <SEP> 1.670
<tb> 8000 <SEQ> 0.5760 <SEQ> 0.3424 <SEQ> 1.682
<tb> 9000 <SEP> 0.6390 <SEP> 0.3771 <SEP> 1.695
<tb> 10000 <SEP> 0.7000 <SEP> 0.4100 <SEP> 1.707
<tb> 11000 <SEP> 0: 7590 <SEP> 1.4411 <SEQ> 1.721
<tb> 12000 <SEP> 0.8160 <SEP> 0.4704 <SEP> 1.735
<tb> 13000 <SEQ> 0.8710 <SEQ> 0.4979 <SEQ> 1.749
<tb> 14000 <SEP> 0.9240 <SEP> 0.5236 <SEQ> 1.765
<tb> 15000 <SEP> 0.9750 <SEP> 0.5475 <SEQ> 1.781
<tb> 16000 <SEP> 1.0240 <SEP> 0.5696 <SEP> 1.798
<tb> 17000 <SEP> 1.0710 <SEP> 0.5899 <SEP> 1.816
<tb> 18000 <SEP> 1.1160 <SEP> 0.6084 <SEP> 1.834
<tb> 19000 <SEP> 1.1590 <SEP> 0.6251 <SEP> 1.854
<tb> 20000 <SEP> 1.2000 <SEP> 0.6400 <SEP> 1.875
<tb> 22000 <SEP> 1.2760 <SEP> 0.6644 <SEP> 1.921
<tb> 25000 <SEP> 1.3750 <SEP> 0.6875 <SEP> 2.000

Table <SEP> 2
<tb> HCHO <SEP> / m3 <SEP> Signal <SEP> in <SEP> Volt
<tb> 0 <SEP> 0.0064
<tb> 28.5 <SEP> 0.0118
<tb> 28.5 <SEP> 0.0113
<tb> 47.5 <SEP> 0.0168
<tb> 47.5 <SEP> 0.0153
<tb><B><U> -95 - </ U></B><SEP> _ <SEP> 0.225
<tb> 142.5 <SEP> 0.241
<tb> 190 <SEP> 0.301
<tb> 237.5 <SEP> 0.359
<tb> 237.5 <SEP> 0.347

Table <SEP> 3
<tb> Content <SEP> in <SEP> Content <SEP> in <SEP> Index <SEP> Content <SEP> Index <SEP> Content <SEP> Index
<tb> CO <SEP> HCHO <SEP> C02
<tb> mg / m3 <SEP> pg / m3 <SEP> N02 <SEP> ppm
<tb> p <SEP> m3
<tb><1<SEP><50<SEP> 0 <SEP><20<SEP> 0 <SEP><650<SEP> 0
<tb> 1 to 2 <SEP> 50 to 75 <SEP> 1 <SEP> 20 to 40 <SEP> 1 <SEP> 650 to 800 <SEP> 1
<tb> 2 <SEP> to <SEP> 4 <SEP> 75 <SEP> to <SEP> 100 <SEP> 2 <SEP> 40 <SEP> to <SEP> 60 <SEP> 2 <SEP> 800 <SEP > to <SEP> 950 <SEP> 2
<tb> 4 <SEP> to <SEP> 8 <SEP> 100 <SEP> to <SEP> * 150 <SEP> 3 <SEP> 60 <SEP> to <SEP> 80 <SEP> 3 <SEP> 950 <SEP> to <SEP> 1100 <SEP> 3
<tb> 8 <SEP> to <SEP> 10 <SEP> 150 <SEP> to <SEP> 200 <SEP> 4 <SEP> 80 <SEP> to <SEP> 100 <SEP> 4 <SEP> 1100 <SEP > to <SEP> 1250 <SEP> 4
<tb> 10 <SEP> to <SEP> 12 <SEP> 200 <SEP> to <SEP> 300 <SEP>. <SEP> 5 <SEP> 100 <SEP> to <SEP> 5 <SEP> 1250 <SEP> to <SEP> 1400 <SEP> 5
<tb> 12 <SEP> to <SEP> 14 <SEP> 300 <SEP> to <SEP> 400 <SEP> 6 <SEP> 120 <SEP> to <SEP> 6 <SEP> 1400 <SEP> to <SEP > 1550 <SEP> 6
<tb> 14 <SEP> 16 <SEP> 400 <SEP> to <SEP> 600 <SEP> 7 <SEP> 140 <SEP> to <SEP> 7 <SEP> 1550 <SEP> to <SEP> 1700 <SEP > 7
<tb> 16 <SEP> 18 <SEP> 600 <SEP> to <SEP> 800 <SEP> 8 <SEP> 160 <SEP> to <SEP> 8 <SEP> 1700 <SEP> to <SEP> 1 <SEP > 8
<tb> 18 <SEP> 20 <SEP> 800 <SEP> to <SEP> 1000 <SEP> 9 <SEP> 180 <SEP> to <SEP> 9 <SEP> 1850 <SEP> to 2000 <SEP> 9
<tb>CO> 20 <SEP><B><U>> 1000 </ U></B><SEP> 10 <SEP>><SEP> 200 <SEP> 10 <SEP>><SEP> to <SEP> 2000 <SEP> 10

Claims (3)

1. Continuous analyzer for volatile organic compounds characterized in that it comprises - a measurement module comprising the sensitive elements of CO / VOC (15) and H20 (16) sensors, and a sequential treatment circuit the air a module (18) for processing and operating the output signals of these sensors, and in that the circuit (18) for the sequential treatment of the air is such that this air is sucked by a pump (17) through a filter (11) and scans the first sensor (15) and the second sensor (16), either directly through a first channel, or after passing through a cartridge (12) of organic species retention through a second way; the switching on one or the other of these two channels being provided by a solenoid valve (13) controlled by a sequencer (14). A device for continuously evaluating the indoor ambient air quality comprising a continuous volatile analyzer according to claim 1, wherein the measurement module also comprises the sensor elements of NO2 (20) and C02 (21), and wherein the sequential treatment circuit of the air sucked by the pump through the filter (11) first scans the third sensor (20) and the fourth sensor (21) before being transferred to the first sensor (15) and the second sensor (16) through the first or second channel. 3. Device according to claim 2, wherein the first the second and the third sensors (15, 16, 20) are chemical microsensors metal oxides. <B> 4. </ B> The device of claim 2, wherein the pump (17) is a diaphragm pump. 5. A method of continuous evaluation of the indoor ambient air quality, using the device according to any one of claims 2 to 4, which comprises the following steps: the calibration curve of each of the sensors (15, 16, 20, 21) for measuring the various compounds: CO / COV, H2O, NO2 and CO2 is determined; the influence of the majority interfering compounds is corrected by calculation; the output signal of each sensor is transposed into measured compound content, taking into account its calibration curve, - a quality index is determined for each compound measured by referring to an evaluation grid which gives a value of index for each compound according to different thresholds of contents of compounds referring to sanitary data, - one obtains overall index of the quality of the air according to the various composite indices obtained. 6. Use of the device according to any one of claims 2 to 4 for controlling a ventilation system.