AIR SAMPLING SYSTEM

Abstract

The subject of the invention is a sampling system which comprises a suitcase, chest or box (1) with a base and a lid, watertight once closed, the suitcase, chest or box containing a plurality of sampling means connected to connectors (2, 3, 4) forming interface means between the sampling means inside the waterproof suitcase, chest or box and the outside, each sampling means comprising a sampling device (18, 24, 26) and a pump (51,...,57) associated with this sampling device.

Description

Field of invention The present invention relates mainly to the sector of ambient air sampling for laboratory analysis in all fields where the aim is to detect the presence of toxic substances, including at trace levels, in the form of gases and dust, when the sampling location is potentially contaminated. The fields of application are numerous and concern measurements in workplaces in the chemical industry, in particular in units using chemical warfare agents, measurements on asbestos removal sites, field measurements in the context of civil or military defense such as samples taken at the scene of accidents or malicious acts, and measurements in a radioactive environment. Technological background The problem in carrying out such samples is twofold. First, it is necessary to ensure the representativeness of the sample, in particular by precisely controlling the volume of air sampled (a source of error would be, for example, the existence of leaks in the sampling circuit). It is therefore necessary that the design of the sampling device guarantees control of the sample, both in terms of its principle and its implementation. in operation. Then it is necessary to prevent the sampling device from being polluted externally, for example by deposit and / or impregnation of pollutants, these external pollutants then being likely to contaminate the environment and personnel by polluting the ambient air or by contact when the sample is extracted from the contaminated area to be transferred to the analysis device. To avoid this pollution, the device must be decontaminated, which implies that the device is capable of withstanding the cleaning products and cycles and that the decontamination does not pollute the samples. The technologies currently available in this sector are of several types. On the one hand, there are sampling means or samplers in the form of adsorption sampling tubes or filters. These samplers constitute samples that can be directly analyzed by the laboratory using known chromatography / mass spectrometry methods. Among this family, we find either very lightweight equipment, allowing sampling on one or even two supports, or transportable equipment allowing multi-support sampling. In both cases, these means are not designed for optimized decontamination and expose individual elements, including sampling supports, which will be handled outside the contaminated area, to contamination. On the other hand, there are air samplers, including polyvinyl fluoride sampling bags (film known under the brand name Tedlar from the DuPont company) or vacuum containers or "canisters". These devices have the major disadvantage of not immediately fixing the substances sought on the analysis support, which can be deposited or adsorbed on the walls of the container during the transfer phase between the sampling location and the analysis location. The sampling yield is therefore reduced. This is particularly important in the case of war toxins such as mustard gas. Finally, still in the field of sampling, document FR2910629A1 concerns a system for sampling and confining chemical contamination intended for the chemical analysis of contamination in particulate and / or molecular form with adsorption by a support or trapping in a liquid and an associated transport device for the transport of chemical contamination to a chemical analysis unit. Brief description of the invention In this context, the present invention aims to design and produce a reliable and easily handled system for sampling atmosphere in contaminated environments and likely to disturb the measurements and the external environment of the device. The system also uses devices that comply with standards, according to standardized methods and can be used by a single operator without assistance, for example for handling the devices. In this context, the present invention proposes a sampling system which comprises a suitcase, chest or box with a base and a lid, waterproof once closed, the suitcase, chest or box containing a plurality of sampling means connected to connectors forming interface means between the sampling means inside the waterproof suitcase, chest or box and the outside, each sampling means comprising a sampling device and a pump associated with this sampling device. The sampling means preferably include gaseous sampling means, i.e. sampling pollutants in gaseous form. The gas sampling means may comprise one or more sampling tubes. The gas sampling means may comprise at least one hydrolyzable gas sampling filter. According to an advantageous embodiment, the sampling means comprise at least one dust sampling filter and a dedicated pump. The gas sampling means are advantageously connected to a first connection constituting a common connection for sampling gaseous substances outside the suitcase, chest or box through a distribution manifold. A dust collection filter is preferably connected to a second connection constituting a dust collection connection outside the suitcase, chest or box. Advantageously, the pump outlets are grouped towards a third connection for discharging air towards the outside of the case through a manifold. Advantageously, the sampling devices are removable. According to a particular embodiment, the sampling devices and the pumps are connected by means of flexible pipes. These pipes are preferably removable. According to a particularly advantageous embodiment, the feeders are connected to the bulkhead crossing fittings by union fittings. The pumps are advantageously programmable pumps in terms of flow rate and operating time. The invention further relates to a method for measuring pollutants using a sampling system according to any one of the preceding claims, comprising a configuration of the suitcase in the laboratory according to the sampling plan with programming of the desired sampling programs in the pumps, connection of the sampling tubes and / or filters; positioning of the sampling tubes and / or filters in the suitcase; a leak test of the complete device by comparing the inlet and outlet flow rates of the suitcase during the pumping phase with the sampling flow rate; a transfer of the suitcase near the sampling area outside the contaminated area; programming of the launch of programmable pumps with the necessary delay before sampling and programming of the sampling duration in line with the capacity of the tubes and filters; entry into a contaminated area; removal of plugs or installation of fitting opening tips; carrying out sampling with automatic triggering and stopping of the pumps; replacing the shutters or removing the opening tips to seal the sampling circuit; exit from the contaminated area with decontamination of the suitcase; a transfer of the suitcase to the laboratory; recovery of tubes / filters for analysis. According to a particular embodiment, the measurement being carried out in an enclosure, the case is connected to the enclosure by means of fluorinated polymer pipes (FEP fluoroethylene propylene) which offer excellent chemical inertia. The method may advantageously include one or more phases of measuring sample blanks before sampling in the contaminated area. The leak test can be carried out more specifically by connecting two flow meters to the inlet and outlet connections of the system, upstream and downstream of the system, by carrying out several simultaneous measurements on the two flow meters with the pumps in operation and by statistically comparing the measurement results using a statistical test. Brief description of the drawings Other characteristics and advantages of the invention will be apparent from reading the following description of a non-limiting example of embodiment of the invention with reference to the drawings which represent: in figure 1: a first example of embodiment of a sampling case according to the invention in top view; in Figure 2A: an exploded view of an example of assembly of the elements in a second example of suitcase according to the invention; in Figure 2B: an enlargement of a portion of Figure 2A; in figure 3: a perspective sectional view of a suitcase cover of the invention provided with a window. Detailed description of embodiments of the invention The invention consists mainly of a sampling system in the form of a suitcase, chest or sampling box comprising adsorption sampling tubes and / or filters. The system of the invention is portable, of low mass, that is to say preferably less than 25 kg; waterproof and decontaminable to ensure that pollutants do not spread beyond the contaminated area. The system includes sampling pumps chosen with reference to a standard relating to ambient air sampling, for example the French standard NF EN 13137 as applicable on the date of filing of this application. The system is designed to be energy-autonomous, particularly by being powered by batteries. It is sized to perform a wide variety of analyses and is modular to adapt to the analysis plan. The system's design in the form of a waterproof suitcase, chest or box protects all components and sampling media from contamination to prevent the spread of pollution during laboratory handling. It is designed to be robust for field use and to protect the integrity of the sampling media. As discussed above the use of analytical substrates such as sampling tubes or sampling filters compared to "air bag" devices allows for greater representativeness of the samples. Figure 1 shows a first example of embodiment of a sampling system of the invention in the form of a sampling case 1 provided with a base 1a and a cover 1b. According to the example shown in Figure 1, the system is sized to be able to take samples simultaneously or sequentially from 6 supports or sampling devices (tubes 24 or filters 18, 26) while ensuring perfect control of the scanning volume of each support. The waterproof case 1, for example of the PELICASE VAL1600 type, is equipped for taking samples with 3 bulkhead crossing connections 2, 3, 4. The connections comprise a first connection 3 for sampling gaseous substances, a second connection 4 for sampling dust, a third connection 2 for discharging all of the sampled air. The connectors provide interfaces between the sampling equipment inside the case, trunk or waterproof box and the outside. When the case is closed, these are the only means of communication between the inside and the outside of the case. According to the example in Figure 1, the connections are instantaneous pneumatic connections through which ambient air can be sampled directly or to which fluorinated polymer (FEP) pipes can be connected, not shown, connecting for example the case to a containment enclosure for controlling the emission of substances. Internal pipes / feeders are connected to the fittings of the case as will be seen later. Inside the suitcase, chest or box, a first gaseous substance sampling line is connected to the first connector 3 by means of a flexible pipe 15, an adapter connector 13, a first multi-way distribution manifold 11, for example reference 3310.06.13 from the company LEGRIS, with a cap 14. The flexible pipe 15 is for example a pipe with a diameter of 6 / 8 mm. In the example of Figure 1, four sampling tubes 24 for thermodesorption analysis are connected to the manifold 11. The sampling tubes 24 are, for example, quarter-inch diameter tubes connected to the feeder after possible diameter adaptation using 23 fittings. Depending on the measurements to be carried out, the tubes are filled with sampling means such as adsorbent substrates and in particular activated carbon intended to capture defined pollutants. For real-time detection use, the case can also be used with colorimetric tubes (Draeger or equivalent) instead of adsorption tubes (tubes visible through the window). The feeder according to the example also includes a sampling channel on an impregnated filter 26 dedicated to the sampling of hydrolyzable gases. Each tube or filter in the line is connected to a programmable independent pump, references 51 to 57, operating on battery power and conforming to a sampling standard, for example in France the NF EN 13137 standard. The pumps are, for example, pumps known under the reference GILAIR Plus from the company SENSIDYNE with a wide flow dynamic between 20 and 5000 cc / min. They must be able to sweep the sampling tubes according to a given flow rate and a given time. The pumps are equipped with a rechargeable battery and USB or other type connection means allowing the recovery of the measured data. The tubes and the filter are connected to their pumps via flexible pipes such as PVC or thermoplastic elastomer pipes, for example, with a quarter-inch diameter. The dust sampling line connected to the connection 4 comprises a flexible pipe 16 with a diameter of 6 / 8 mm, adaptation connections 16, 19, a cassette filter 18 here with a diameter of 37 mm, a programmable independent pump 10, operating on battery of the same type as for the sampling channels above. The case also includes a second multi-way feeder 12 (for example, reference 3310.06.13 from the company LEGRIS), with a cap 31. The second manifold is connected to the outlets of pumps 51 to 56 by means of flexible pipes 21. These pipes are in particular quarter-inch diameter pipes. This second manifold is intended to collect all the flows leaving the pumps and is connected to the discharge connection 2 via a flexible pipe 32, for example a pipe with a diameter of 6 / 8 mm and possibly an adapter connection 30. The material of the various flexible pipes of the sampling systems of the version described in Figure 1 is chosen to minimize losses of substances by absorption on the walls. This material should preferably be a fluoropolymer (FEP). The case is designed to reduce the length of the flexible pipes upstream of the adsorption tubes and sampling filters, always to minimize adsorption losses. The use of the first manifold 11 makes it possible to group the samples of gaseous substances on a single wall crossing at the level of the first connection 3. However, the sampling of dust, when necessary, is carried out on a dedicated path via the second connection 4, so that there is no accumulation of dust in the manifold 11 which would be detrimental to the accuracy of the sampling. Plugs can be used to block the unused connections. The use of dedicated pumps 51, ..., 57 programmable in flow rate and operating time and not a single pump suction via a manifold allows for an exact measurement of the volume of air that has swept through each tube and / or filter and consequently for obtaining reliable concentration measurements. The pumps are programmable. The unique combination of a sampling support and a pump allows for slightly delayed pump starts without compromising measurement accuracy due to the flow rate and sampling time control on each pump. Programmable pumps may include sets of pre-established sampling programs selected by the user depending on the sampling to be carried out. Programming and exploitation of pump results can be done with the pumps outside the case and mounted on a docking station equipped with means of recharging the pump battery and a computer link to a computer workstation or directly on a pump interface screen. Figure 2A shows a variant of the suitcase comprising 7 sampling supports. According to this example, which constitutes the preferred embodiment of the invention, the manifolds 11 and 12 are directly connected to the bulkhead crossing fittings by means of union fittings allowing the manifolds to be oriented in the case. Similarly, the gas sampling tubes are connected directly to the manifold by cap fittings, which makes it possible to avoid the use of FEP pipes with a large radius of curvature. The gaseous substance sampling, dust sampling and discharge lines are integrated into the case, for example of the PELICASE 1600 type. These lines constitute the internal fluid circuit of the sampling system. The sampling of gaseous substances is carried out through 6 sampling channels. Each channel consists of the following elements: A sampling pump 51 to 56 of known type with data acquisition and pressure and temperature correction, a sampling tube 24 for channels 1 to 5 and a filter cassette 34 for channel 6. An 8-way stainless steel connection block or manifold 11 more particularly shown in Figure 2B on which the filters are mounted directly, via ring or cap connectors 111 for the tubes, and via a luer connector 112 for the filter holder cassette 34. The manifold or connection block 11 allows a common supply of these 6 sampling channels. The inlet of this connection block is connected via a union connector 63 to a connector 3 mounted across the bulkhead on the case. The connections between the filters and the sampling pumps are made with flexible tubing such as a thermoplastic elastomer known under the brand name TYGON. A single channel allows dust sampling and its supply is separate from the sampling of gaseous substances. It consists of the following elements: A sampling pump with data acquisition and pressure and temperature correction, an 18a filter cassette equipped with luer adapters, a 4 connector, for example a connector manufactured by the Staubli company under the reference NCB04, mounted across the bulkhead on the case and connected to the filter cassette by a 63 union connector. The connection from the 18a filter to the sampling pump is made with flexible TYGON tubing with an internal diameter of h4 inches. Returning to Figure 2A, the discharges from the 7 sampling channels are channeled to an 8-way stainless steel connection block or manifold 12 equipped with barbed fittings. The 7 pumps are equipped with an adapter allowing a connection using TYGON tubing with an internal diameter of h4" to the stainless steel connection block. This connection block is connected to a connection 2, for example of the Staubli NCB04 type, mounted across the bulkhead on the case. As seen previously, the connections 2, 3, 4 for example of the Staubli NCB04 type mounted across the bulkhead on the case allow the case to interface with the equipment. Still shown in Figure 2A and in order to reduce the number of holes in the case and to reduce the risks of loss of internal sealing, all of the internal elements needing to be held in position are fixed on a mounting plate 6 0 for example an aluminum plate. Fixing means 61 on the mounting plate allow it to be held in position thanks to non-opening holes made inside the case. The pumps are fixed on supports 62 which are themselves fixed on the mounting plate 60. The pumps 51 to 57 have sufficient space allowing them to be easily removed and replaced. The union fittings 63 mounted between the bulkhead fittings 2, 3, 4 and the connection blocks make the elements easily removable and allow them to be positioned angularly in the case. In the example of figure 2A and more particularly visible in figure 2B, one of the tubes 241, connected to the pump 55 is preceded by a filter with desiccant material 33. and an additional channel connected to the pump 56 comprises a filter holder cassette 34. In the embodiment of Figure 2A, the bulkhead crossing connections 2, 3, 4 are naturally closed (self-sealing) connections and their opening is achieved by the introduction of a tip or plug 64 adapted to open the connection. These fittings are self-sealing with no dead volume (e.g. NCB fittings from STAUBLI). They are therefore not passable during the waiting phase, which guarantees the case's watertightness. The 64 plugs are added during the sampling phase to make them passable and then removed before decontamination. The fittings and feeders will be metallic in order to allow decontamination by washing with solvent following sampling of substances causing residual internal contamination. Such contamination can be detected when carrying out sampling blanks which consist of taking measurements in an unpolluted environment, then allowing the blank measurement values to be subtracted from the measurements subsequently carried out in the place to be tested to obtain the actual value of excess pollutants (In the case of a non-ubiquitous substance such as a war toxicant, the value of this blank must be zero). In addition, in the event of persistent contamination, the selection of standard components in the field of pneumatic networks makes it possible to consider replacing parts at a controlled cost. In the case of Figure 1, following a sample taken in an area that is actually polluted, pipes 15, 16 and 22 between the inlet connections 3, 4 and the sampling devices will preferably be replaced. In the case of the example in Figure 2A, the fittings and manifold are cleaned. Figure 3 shows the cover of a sampling case provided with a glass wall 40 integrated on the top of the case in order to have visibility on the pump screen when the case is used closed. To integrate the glass wall, an opening is made on the top of the lid 1b of the case. The glass is held in a vice between 2 flat gaskets 43, 44 which provide a seal at the joint plane. A stainless steel upper frame 42 and a stainless steel counter plate 41 inside the case assembled by a set of screws, washers, gaskets, washers and nuts allow the glass to be held in position and fixed to the case. The implementation of the invention involves the following steps: Configuration of the suitcase in the laboratory according to the sampling plan with programming of the desired sampling programs in the pumps, connection of the sampling tubes and / or filters; Positioning of the sampling tubes and / or filters in the suitcase; Leaktightness check of the complete device by comparing the inlet and outlet flow rates of the suitcase during the pumping phase with the sampling flow rate; The leak test is carried out in particular by connecting two flow meters, preferably soap blade flow meters to increase measurement accuracy, to connections 2 and 3, i.e. upstream and downstream of the system. With the pumps in operation, the operator takes simultaneous measurements on both flow meters. Even if these precision devices have a low measurement dispersion, this still exists, which has the following consequences: consequence that a perfectly sealed circuit will not give strictly the same measurement value upstream and downstream. This is why it is advisable to compare the measurement results statistically. For example, two samples of 20 measurements (one upstream sample and one downstream sample) can be created and compared using a statistical test, for example a Kolmogorov-Smirnov test, with a confidence level of 95%. Then, one or more phases of measuring sample blanks are possibly carried out; The following phases are: Transfer of the suitcase near the sampling area outside the contaminated area; Programming the launch of programmable pumps with the necessary delay before sampling and programming the sampling duration in line with the capacity of the tubes and filters; Entry into contaminated area; Removing the plugs or installing the fitting opening tips; Carrying out sampling with automatic triggering and stopping of the pumps, the operator being able to check that the pumps are triggered correctly through the window; Installation of shutters or removal of opening tips to seal the sampling circuit; Exit from the contaminated area with decontamination of the suitcase; Transfer of the suitcase to the laboratory; Recovering tubes / filters for analysis. If the measurement is carried out in an enclosure, the case is connected to the enclosure using fluorinated polymer pipes (FEP fluoroethylene propylene) which offer excellent chemical inertia. The invention is not limited to the examples shown and in particular as indicated above it is possible according to the invention to design a case comprising more or fewer measuring channels.

Claims

CLAIMS » 1 - Method for measuring pollutants by means of a sampling system comprising a suitcase, chest or box (1) which is watertight once closed, the suitcase, chest or box containing a plurality of sampling means connected to connectors (2, 3, 4) forming interface means between the sampling means inside the suitcase, chest or watertight box and the outside, each sampling means comprising a sampling device (18, 24, 26) and a pump (51, ..., 57) programmable in flow rate and operating time associated with this sampling means, characterized in that it comprises: configuration of the suitcase in the laboratory according to the sampling plan with programming of the desired sampling programs in the pumps of each sampling device, connection of the sampling tubes and / or filters; positioning of the sampling tubes and / or filters in the suitcase; - a leak test of the complete device by comparing the inlet and outlet flow rates of the suitcase during the pumping phase with the sampling flow rate; - transfer of the suitcase near the sampling area outside the contaminated area; programming of the launch of programmable pumps with the necessary delay before sampling and programming of the sampling duration in line with the capacity of the tubes and filters; - entry into a contaminated area; - carrying out sampling with automatic triggering and stopping of the pumps; - exit from the contaminated area with decontamination of the suitcase; - transfer of the suitcase to the laboratory; - recovery of tubes / filters for analysis. 2 - Method according to claim 1 for which the connections being provided with removable shutters or opening tips, the method comprises before sampling a step of removing the shutters or installing the opening tips of the connections and after sampling, a step of replacing the shutters or removing the opening tips to seal the sampling circuit; 3 Method for measuring pollutants according to claim 1 or 2, for which, the measurement being carried out in an enclosure, the suitcase is connected to the enclosure by means of fluorinated polymer pipes (FEP fluoroethylene propylene). 4 - Method for measuring: pollutants according to claim 1, 2 or 3 comprising one or more phases of measuring sample blanks before sampling in the contaminated zone. 5 - Method for measuring pollutants according to any one of claims 1 to 4 for which the leak test is carried out by connecting two flow meters to the inlet and outlet connections of the system, upstream and downstream of the system, by carrying out several simultaneous measurements on the two flow meters with the pumps being put into operation and by statistically comparing the measurement results by a statistical test. 6 - Sampling system for implementing the method according to any one of claims 1 to 5, characterized in that it comprises a case, watertight once closed, the case, trunk or box containing a plurality of sampling means connected to connectors (2, 3, 4) forming interface means between the sampling means inside the case, trunk or waterproof box and the exterior, each sampling means comprising a sampling device (18, 24, 26) removable and a pump (51, ..., 57) programmable in flow rate and operating time associated with this sampling device and a station for programming the measurements of said suitcase. 7 - Sampling system according to claim 6 for which the sampling means comprise gas sampling means (24, 26) comprising sampling tubes (24) and / or at least one filter (26) for sampling hydrolyzable gases. 8 - Sampling system according to claim 6 or 7 for which the sampling means further comprise at least one dust sampling filter (18) and a dedicated pump (10). 9 - Sampling system according to any one of claims 6 to 8 for which the gas sampling means (24, 26) are connected to a first connector (3) constituting a common connection for sampling gaseous substances 20 from outside the suitcase, chest or box through a distribution manifold (11). 10 - Sampling system according to claim 9 for which the sampling filter is connected to a second connection (4) constituting a dust sampling connection 25 outside the suitcase, chest or box. 11 - Sampling system according to any one of claims 6 to 10 for which the outlets of the pumps (51, ..., 57) are grouped towards a third connection (2) 30 for discharging air towards the outside of the case through a distribution manifold (12). 12 - Sampling system according to claims 9 and 11, for which the distribution feeders are connected to the bulkhead crossing fittings (2, 3) by union fittings (63). ' 13 - Sampling system according to any one of claims 6 to 12 for which the sampling devices and the pumps are connected by means of removable flexible pipes. 14 - Sampling system according to any one of claims 6 to 13 for which the programming station is a docking station equipped with means for recharging the battery of the pumps and a computer link to a computer workstation.

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