Method for determining the trichloramine content in air and device for carrying out the method

Abstract

The invention relates to a method for determining, in particular calculating, the trichloramine content (NCl3) in air, in particular in a swimming pool, wherein a measurement of at least one surrogate of trichloramine (NCl3) present in the air in addition to the trichloramine (NCl3) is carried out and the determination, in particular calculating, of the trichloramine content (NCl3) is carried out at least partially on the basis of the at least one measured surrogate value.

Description

[0001] The invention relates to a method for determining the trichloramine content according to claim 1. Furthermore, the invention relates to a device for carrying out the method according to the invention, a computer-readable storage medium and the use of a specific trichloramine content for controlling a water treatment system and / or an air treatment system of a swimming pool.

[0002] For the safe disinfection of swimming pools, the WHO and most health authorities prefer chlorination of pool water, and it is usually mandatory. Free chlorine, as HOCl, is initially converted into monochloramine by the introduction of bound nitrogen (e.g., sweat and / or urea from swimmers) or other contamination sources. If chlorine is still available, especially free chlorine (excess chlorine), it is converted into dichloramine or trichloramine.

[0003] The reaction can be simplified as follows:

[0004] In indoor swimming pools, the increase in chlorine by-products in the water can be measured using various methods. Legally, colorimetric or even photometric monitoring of the auxiliary value "combined chlorine" is usually required at varying intervals. In addition, total chlorine and free chlorine levels are measured using sensors in some facilities, and the difference is sometimes used for control optimization.

[0005] In some countries, such as Belgium and the Netherlands, the measurement of urea was or is required by regulation or standard. Measurement of potassium permanganate (KMnO4) consumption, a TOC (total organic carbon), or a TON (total organic nitrogen) value can also be used to determine organic pollution. However, these water quality measurements can currently only be performed using complex laboratory methods.

[0006] With each oxidation of nitrogen compounds, the volatility of the chloramine compound is increased and so trichloramine, due to its high Henry's constant of 435, evaporates particularly easily from the water after the water interface has been breached, especially when this is facilitated by the wave movements on the interface caused by facilities such as bubbles, waterfalls, etc. and the movement of bathers.

[0007] The resulting contamination of indoor air caused by the release of trichloramine (NCl3) in swimming pools and other workplaces that use heavily chlorinated open pools, for example, for cleaning fruit and vegetables, is well known and was published more than 20 years ago by, among others, the French National Institute for Research and Security (INRS). This has led to the development of various measurement methods.

[0008] Trichloramine also accelerates corrosion, especially in warm, humid environments such as swimming pools, and has repeatedly caused damage in the past from falling structural components due to the breakage of suspensions. The collapse of entire roof structures is also known and is attributed to so-called "stress corrosion cracking."

[0009] Specifically, the release of trichloramine and other chlorine by-products can damage structural components of systems, for example, through the formation of hydrochloric acid from contaminated room air condensate, and thus significantly shorten their service life. Especially in suspended structures or other equipment such as soundproofing panels, these components are then subjected to severe static loads and, once weakened, can even break, and in extreme cases, lead to the collapse of such components or even suspension devices.

[0010] The problem of trichloramine contamination in indoor air, especially in swimming pools, has been discussed for years, so that recommended limit values have been published by various authorities, with the focus usually being on employee protection.

[0011] In France, secondary illnesses caused by high levels of trichloramine have now been recognized as occupational diseases among swimming pool staff, meaning that affected swimming pool staff are entitled to, for example, early retirement and appropriate rehabilitation. Determining the NCl3 concentration in the air is therefore of economic importance for avoiding claims for recourse by swimming pool operators.

[0012] The precise determination of trichloramine in the air is sometimes difficult due to interference with other chemicals in the air of swimming pools.

[0013] A well-known measurement method for specific monitoring periods, e.g., a one-hour peak exposure or an 8-hour continuous exposure, for monitoring trichloramine exposure for the purpose of worker protection largely eliminates these interferences. The measurement method utilizes enrichment from the hall air through targeted air circulation to a specific storage medium during a specific period, e.g., 8 hours, and analyzes the dissolved amount by diluting and adding a specific reagent and photometrically determining the color change. However, this method requires a significant amount of time and personnel due to the various required steps.

[0014] In addition, a reliable online method for determining trichloramine exposure has now been established. This technology is described, among other things, in EP 2 652 494 and allows determination at significantly shorter intervals of, for example, 10 minutes and significantly better accuracy through profiling of the results over the course of the day. The method is based on the color change that a monolith exposed to swimming pool air or other contaminated air, for example in the form of a plate that is stabilized and held by a holding device, undergoes over a certain period of time (e.g. 10 minutes) by means of photometric measurement as it binds trichloramine. The measurement result is then compared. The color change is designed for a specific exposure level, so that the monolith plate must be replaced after a certain time.

[0015] All recorded values can be stored chronologically with a time stamp and displayed externally via various software programs, or accessed via cloud access if necessary. However, as described above, the disadvantage is that the coated, dispersed monolith plates require regular replacement, e.g., daily.

[0016] Based on this prior art, the present invention aims to provide an advanced method for determining trichloramine levels, particularly for determining trichloramine levels in indoor swimming pools. The aforementioned disadvantages, particularly the need for daily replacement of dispersed monoliths, especially coated, dispersed monolith plates, are to be overcome by means of an advanced method. Furthermore, the present invention aims to provide a device for carrying out the advanced method.

[0017] A further object of the present invention is to provide a further developed use of a determined, in particular calculated, trichloramine content (NCl3) in air, wherein the trichloramine content was preferably determined, in particular calculated, according to the invention.

[0018] This object is achieved according to the invention with regard to the method by the subject matter of claim 1, with regard to the device by the subject matter of claim 12, by the inventive computer-readable storage medium of claim 14 and by the inventive use according to claim 15.

[0019] Numerous specific details are discussed below to provide a comprehensive understanding of the subject matter of the present application. However, it will be apparent to one skilled in the art that the subject matter of the application can be practiced and reworked without these specific details.

[0020] All features of one embodiment may be combined with features of another embodiment if the features of the different embodiments are compatible.

[0021] The terminology used in the description of the present disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the subject matter. As used in this description and the claims, the singular forms "a," "an," and "the" are intended to include the plural forms, unless the context clearly dictates otherwise. The reverse is also true, meaning that the plural forms are intended to include the singular forms. It is also to be understood that the term "and / or," as used herein, refers to and includes all possible combinations of one or more of the related listed elements.It is further understood that the terms "includes," "including," "comprises," and / or "comprising," when used in the present description and claims, specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0022] In the present description and claims, the terms "includes", "comprises" and / or "comprising" may also mean "consisting of", that is, the presence or addition of one or more other features, steps, operations, elements, components and / or groups is excluded.

[0023] The method according to the invention for determining, in particular calculating, the trichloramine content (NCl3) in air, in particular in a swimming pool, is based on measuring at least one surrogate of trichloramine (NCl3) present in the air in addition to trichloramine (NCl3) and determining, in particular calculating, the trichloramine content (NCl3) at least partially on the basis of the at least one measured surrogate value.

[0024] In the following, the determination of the trichloramine content (NCl3) in air is preferably understood to mean a calculation and / or estimation of the trichloramine content (NCl3) in air, whereby at least one (initial) measurement of the trichloramine content (NCl3) can also be carried out in combination for the calculation and / or estimation.

[0025] In other words, the method according to the invention can be based on the measurement of at least one surrogate of trichloramine (NCl3) present in the air, and the determination or calculation of the trichloramine content (NCl3) as an equivalent, at least in part, based on the at least one measured surrogate value. The explicit measurement of a trichloramine content can be used to calibrate the determination, in particular the calculation, of the trichloramine content based on the measurement of a surrogate value.

[0026] The at least one surrogate is preferably carbon dioxide (CO2) and / or nitrogen dioxide (NO2) and / or nitrogen monoxide (NO) and / or a volatile organic compound (VOC) and / or a particulate matter (PM) content.

[0027] In one embodiment of the invention, it is possible that at least two of the mentioned surrogates or surrogate values are determined for the determination, in particular calculation, of the trichloramine content (NCl3) in air.

[0028] In a first preferred embodiment of the invention, only a measured carbon dioxide value (CO2) is used as a surrogate.

[0029] In a further preferred embodiment of the invention, a measured carbon dioxide value (CO2) and a measured nitrogen dioxide value (NO2) are used as surrogates.

[0030] In a further preferred embodiment of the invention, a measured carbon dioxide value (CO2) and a measured nitrogen dioxide value (NO2) and a particulate matter content (PM) measured in the air are used as surrogate.

[0031] It is possible to use the number of people present in a swimming pool when determining, or in particular calculating, the trichloramine (NCl3) content in the air of a swimming pool. In addition or alternatively, it is possible to use the number of people in a swimming pool when determining, or in particular calculating, the trichloramine (NCl3) content in the air of a swimming pool. It has been shown that the release of trichloramine and other dissolved gases from the water increases with movement in the water and thus with increasing numbers of people.

[0032] It is possible that when determining, in particular calculating, the trichloramine content (NCl3) in the air of a swimming pool, at least one measured water parameter, in particular bound chlorine and / or UV254 and / or parameters that may represent similar organic contamination, is also used.

[0033] In one embodiment of the invention, for the determination, in particular calculation, of the trichloramine content (NCl3), an initial measurement of the trichloramine content (NCl3) is carried out at least before carrying out the determination, wherein the measurement of the trichloramine content (NCl3) is preferably repeated at regular time intervals.

[0034] With the aid of the initial measurement of the trichloramine content (NCl3) and / or with the aid of a regular repetition of the measurement of the trichloramine content (NCl3), a type of calibration of the determination, in particular calculation, of the trichloramine content (NCl3), preferably as an equivalent (surrogate), is preferably carried out. This calibration can concern the determination of a calculation factor to be used in the calculation and / or the calibration of a device, in particular a sensor device and / or sensor unit, for measuring at least one surrogate content.

[0035] Preferably, the measured trichloramine content (NCl3), in particular the initially measured trichloramine content (NCl3), can be used to determine a factor with the aid of which a determination, in particular calculation, of the trichloramine content (NCl3) is carried out on the basis of the at least one measured surrogate value.

[0036] For example, it has been shown that the following factors result for the surrogates carbon dioxide (CO2), nitrogen dioxide (NO2) and particulate matter (PM) in relation to trichloramine (NCl3): Table 1 NCl 3 [ppb] CO 2 [ppm] - as a difference value to a CO 2 -Baseline value of 424 ppm NO2 [ppb] PM [µm / m 3 or ppb] as the sum of 4 measuring ranges 1 3,16 1 3,64 1 0,17

[0037] A measurement of the trichloramine content (NCl3) repeated at regular time intervals can be used, for example, to recalibrate the calculation factor to be used and / or to recalibrate a device, in particular a sensor device and / or sensor unit, for measuring at least one surrogate content.

[0038] It should be noted that temperature and, depending on it, (relative) humidity can, under certain conditions, also influence the measurement accuracy and / or sensor accuracy, and thus indirectly the surrogate values. In other words, temperature and, depending on it, (relative) humidity can, under certain conditions, also influence the measurement accuracy and / or sensor accuracy, and thus indirectly the trichloramine measurement, its accuracy, and that of the surrogate values.

[0039] By taking these measured values, namely temperature and / or humidity and / or relative humidity, into account, the quality and accuracy of the results can be further improved if necessary.

[0040] In indoor swimming pools, there is also the problem that swimmers / bathers release significant amounts of urea, sweat and other organic compounds into the pool water, which then oxidise with the legally prescribed chlorine compounds to form organic chlorine side reaction products such as chloramine, chloroform and other trihalomethanes.

[0041] VOC sensors can detect such compounds. The detected VOC values can be used to determine, and especially calculate, trichloramine levels. Studies have shown that the use of UV systems for water treatment in conjunction with chlorine also increases the formation of trichloramine and other chlorine substitution products, which can be reflected in an increased VOC value.

[0042] In any case, NO2 is produced in such significant quantities that a clear measurement is possible. In other words, nitrogen dioxide (NO2) can be measured as an alternative or supplementary surrogate value.

[0043] It is possible to use NO2 sensors and / or NOx sensors to perform the process. The advantage of using NOx sensors is that they analyze both nitrogen dioxide (NO2) and nitrogen monoxide (NO), although NO is only present in small amounts in swimming pools. However, NO can be present in higher concentrations in other waters.

[0044] CO2 measurements are also suitable as surrogate measurements. However, it should be noted that due to the often high exchange with outside air, CO2 levels can be significantly influenced by meteorological and climatic fluctuations, as well as domestic combustion and other influencing factors.

[0045] It is possible to perform and / or calculate a CO2 measurement based on a baseline CO2 level. A baseline CO2 level could, for example, be the global average, i.e., the average CO2 level present in the atmosphere globally. In May 2022, this global average CO2 level was 421 ppm in the atmosphere. This global average CO2 level corresponds to approximately 0.04%.

[0046] Alternatively, a baseline CO2 level can be a minimum CO2 level measured locally outside a swimming pool. This minimum CO2 level is influenced by changing external contamination (e.g., from fossil fuels from traffic, domestic heating, or industry).

[0047] It is advantageous to regularly repeat the measurement of the minimum CO2 level prevailing locally outside a swimming pool. This allows a difference between the minimum CO2 level and the measured CO2 level to be calculated using a CO2 level measured in a swimming pool. This difference can be used as a surrogate value for a trichloramine level to be determined, particularly calculated. The local or other baseline CO2 level can also be retrieved from a weather database, for example, so that this retrieved baseline CO2 level can be taken into account when determining forecast values and for optimizing control systems.

[0048] As already stated above, visitor exposure to a swimming pool can have a significant impact on the level of trichloramine in the indoor air, especially in the indoor pool air. Measuring visitor exposure using access control values, e.g., from light barriers or turnstiles, and / or people counting using optical systems allows this influence to be taken into account, which can be directly incorporated into the scaling of individual measurement parameters.

[0049] It is possible for at least one optical system to be installed in a swimming pool of an indoor swimming pool. Such an optical system can be used to determine the number of people in the pool.

[0050] At least one optical system, which can be located both outside and inside a swimming pool, allows - optionally with the application of AI - to use the number of people in a swimming pool and / or in a swimming pool when scaling individual measurement parameters.

[0051] Some competition facilities also have larger visitor stands, so separate counting of this access area can significantly improve the quality of results, for example, in CO2 measurements. Furthermore, the number of swimmers in the pool itself can serve as an indicator of the expected organic contamination of the pool water. It has been shown that the type of movement and the resulting wave refraction can promote the release of dissolved substances, such as trichloramine, into the indoor air.

[0052] Regular recalibration can further optimize the quality of the calculation. AI solutions can also be applied in this process.

[0053] The method according to the invention enables a significant simplification of trichloramine determination, a reduction in costs through the use of sensors instead of chemical methods for trichloramine determination and an efficient method to optimize the control of ventilation systems and water treatment plants, as well as to determine criteria such as the determination of a corrosion index, bathing comfort and staff exposure.

[0054] For the preferred determination of values regarding trichloramine concentrations in the air, especially in a swimming pool, modeling calculations are also suitable. These calculations use not only the values measured in the swimming pool but also external values from on-site sensors or forecast values from meteorological services. Sensors such as people counting applications at the entrance (e.g., turnstiles, light barriers) or digital counting using room sensors, which can determine the number of people in a specific area based on movement profiles, can also be used. This can improve the quality of the forecast.

[0055] By performing predictions, for example, at least one water treatment plant and / or one air treatment plant can be controlled.

[0056] In addition to actual values, predicted values can also be calculated on-site or in a cloud application and used to control ventilation systems in order to save energy for circulation / ventilation and heating / heat recovery.

[0057] The determined, in particular calculated using a surrogate, trichloramine content (NCl3) in air can be used to control a water treatment plant and / or to control an air treatment plant, wherein the determined, in particular calculated, trichloramine content (NCl3) in air is / are preferably transmitted to a control device of a water treatment plant and / or an air treatment plant.

[0058] The control of a water treatment plant and / or an air treatment plant can be further improved by the present teaching by using the measured and / or determined and / or calculated trichloramine value or measured and / or determined and / or calculated surrogate value as control parameters for the control of the water treatment plant and / or the air treatment plant.

[0059] It is possible that the determined, in particular calculated, trichloramine content is compared with a previously defined and / or standardized and / or legally prescribed trichloramine limit value and / or a previously defined trichloramine range and, if the previously defined trichloramine limit value and / or the previously defined trichloramine range are exceeded and / or undercut, a change in the water treatment, in particular a change in the process combination of a water treatment plant, and / or a change in the air treatment is / are carried out with the aid of the control device of the water treatment plant and / or the air treatment plant.

[0060] In one embodiment of the invention, the circulation capacity of the water treatment plant and / or the added amount of at least one water treatment agent and / or the content of at least one water treatment agent and / or at least one treatment step in a device bypass can be controlled with the aid of the control device of the water treatment plant.

[0061] The water treatment agent may be chlorine and / or flocculants and / or flocculating agents and / or oxidizing agents.

[0062] The chlorine mentioned can be present, for example, as chlorine gas, sodium hypochlorite or calcium hypochlorite.

[0063] The flocculant can be, for example, polyaluminium chloride, sodium aluminate or iron III compounds or combinations thereof.

[0064] The flocculation agent can, for example, be a silicic acid aluminate solution.

[0065] The oxidizing agent may, for example, be a tetrachlorodecaoxide complex and / or a chlorine dioxide solution and / or a peroxide compound.

[0066] In a particularly preferred embodiment of the invention, the determined, in particular calculated, trichloramine content (NCl3) in air and additionally the measured value of bound chlorine in the water of a swimming pool are evaluated when controlling a water treatment plant.

[0067] The combined chlorine content can be measured, for example, by measuring free chlorine and total chlorine, followed by calculating the difference. The free chlorine and total chlorine are preferably measured using a separate electrode.

[0068] A treatment step in a device bypass may, for example, be stripping and / or UV irradiation and / or ozone treatment and / or cleaning / absorption by means of activated carbon filters.

[0069] To carry out at least one of the treatment steps mentioned, a device bypass of a water treatment plant preferably has at least one stripping device, for example at least one packing, and / or a UV irradiation device and / or at least one ozone generator and / or at least one filter filled with activated carbon or other absorbing material.

[0070] In a further embodiment of the invention, the amount of fresh air supplied and / or the total circulation capacity of the air treatment system can be controlled with the aid of the control device of the air treatment system.

[0071] It is possible that the determined, in particular calculated, trichloramine content (NCl3) in air is used to control a dehumidification device and / or a heating device and / or a cooling device and / or a ventilation device.

[0072] From an economic and qualitative point of view, this means that energy costs, operating times and treatment quality can be optimized, both with regard to water treatment and / or air treatment.

[0073] All or individual values measured and / or determined values and / or calculated values and / or predicted values within the scope of the method according to the invention can be stored chronologically with a time stamp.

[0074] Furthermore, it is possible that all or individual values measured and / or determined values and / or calculated values and / or predicted values within the scope of the method according to the invention are displayed via an external access and / or via various software programs or, if necessary, retrieved via a cloud access.

[0075] Particularly preferably, all or individual values measured and / or determined values and / or calculated values and / or predicted values within the scope of the method according to the invention can be output to external systems, such as an external memory and / or an external computer, by means of protocols such as Modbus / MQTT.

[0076] A further aspect of the invention relates to a device for carrying out a method for determining, in particular calculating, the trichloramine content (NCl3) in air, in particular for carrying out a method according to the invention.

[0077] According to the invention, the device comprises a sensor unit and a computing unit, wherein the sensor unit comprises at least one carbon dioxide sensor (CO2) and / or a nitrogen dioxide sensor (NO2) and / or a nitrogen monoxide sensor (NO) and / or a sensor for detecting volatile organic compounds (VOC) and / or a NOx sensor and / or a particulate matter sensor.

[0078] In a further embodiment of the invention, the sensor unit comprises a trichloramine sensor (NCl3). This is particularly advantageous if the method to be carried out for determining, in particular calculating, a trichloramine content (NCl3) comprises at least one initial measurement of the trichloramine content (NCl3), preferably one measurement to be repeated at time intervals.

[0079] A sensor unit can be understood as a device that has at least one of the above-mentioned sensors. A sensor unit can also be a device that has several of the above-mentioned sensors.

[0080] It is also possible for the sensor unit to be designed in such a way that, when multiple sensors are used, they are not structurally connected to one another. The sensors can be formed in several separate components. Alternatively, a component group can be formed. This facilitates the installation of a sensor unit in a room, for example, in a swimming pool.

[0081] It is possible for the sensor unit to comprise at least one of the sensors mentioned, i.e. at least one carbon dioxide sensor (CO2) and / or one nitrogen dioxide sensor (NO2) and / or one nitrogen monoxide sensor (NO) and / or one sensor for detecting volatile organic compounds (VOCs) and / or one NOx sensor and / or one particulate matter sensor, wherein this sensor is in the form of an optical particle counter (OPC). In the optical particle counter, particles are guided in a targeted manner through the beam of a light source (usually a laser beam), and the resulting scattered light is captured and evaluated by a photodiode.

[0082] In a preferred embodiment of the invention, the device comprises a plurality of particulate matter sensors, i.e., at least two particulate matter sensors. The design of four particulate matter sensors has proven particularly advantageous.

[0083] A further aspect of the invention relates to a computer-readable storage medium containing instructions that cause at least one processor to implement a previously described method according to the invention when the instructions are executed by the at least one processor.

[0084] In connection with the computer-readable storage medium according to the invention, the same or similar advantages arise as those already mentioned in connection with the method according to the invention.

[0085] A further aspect of the invention relates to the use of a specific, in particular calculated, trichloramine content (NCl3) in air, particularly preferably a trichloramine content (NCl3) in air determined according to the invention, in particular calculated, for controlling a water treatment plant and / or for controlling an air treatment plant of a swimming pool.

[0086] In one embodiment of the invention, the circulation capacity of the water treatment plant and / or the added amount of water treatment agents and / or the content of water treatment agents and / or at least one treatment step in a device bypass is / are controlled with the aid of the control device of the water treatment plant.

[0087] Alternatively or additionally, it is possible for the amount of fresh air supplied and / or the total circulation capacity of the air treatment system to be controlled with the aid of the control device of the air treatment system.

[0088] In connection with the use according to the invention of the determined, in particular calculated, trichloramine content (NCl3) in air, particularly preferably of a trichloramine content (NCl3) in air determined according to the invention, in particular calculated, for controlling a water treatment plant and / or an air treatment plant of a swimming pool, all details mentioned in connection with the method according to the invention and the advantages to be achieved thereby apply.

[0089] Within the scope of the use according to the invention, it is possible that the determined, in particular calculated, trichloramine content is compared with a previously defined and / or standardized and / or legally prescribed trichloramine limit value and / or a previously defined trichloramine range and, if the previously defined trichloramine limit value and / or the previously defined trichloramine range are exceeded and / or undershot, a change in the water treatment and / or air treatment is carried out with the aid of the control device of the water treatment plant and / or the air treatment plant.

[0090] The water treatment agent may be chlorine and / or flocculants and / or flocculating agents and / or oxidizing agents.

[0091] The chlorine mentioned can be present, for example, as chlorine gas, sodium hypochlorite or calcium hypochlorite.

[0092] The flocculant can be, for example, polyaluminium chloride, sodium aluminate or iron(III) compounds or combinations thereof.

[0093] The flocculation agent can, for example, be a silicic acid aluminate solution.

[0094] The oxidizing agent may, for example, be a tetrachlorodecaoxide complex and / or a chlorine dioxide solution and / or a peroxide compound.

[0095] A treatment step in a device bypass may, for example, be stripping and / or UV irradiation and / or ozone treatment and / or cleaning by means of an activated carbon filter.

[0096] It is possible that the determined, in particular calculated, trichloramine content (NCl3) in air is used to control a dehumidification device and / or a heating device and / or a cooling device and / or a ventilation device.

[0097] From an economic and qualitative point of view, this means that energy costs, operating times and treatment quality can be optimized, both with regard to water treatment and / or air treatment.

[0098] The invention is explained in more detail below using exemplary embodiments.

[0099] The figures described below show: Fig. 1 measured trichloramine, carbon dioxide and nitrogen dioxide values in direct comparison; Fig. 2 graphs of the measured values after value scaling and time adjustment; Fig. 3 Swimming pool in which the test setup was carried out; Fig. 4 Representation of the swimming pool according to Fig. 3 with dimensions; Fig. 5 Representation according to ASHRAE standard; Fig.6 Example surrogate measurements including particulate matter measurements; and Fig. 7 Further measurements using visitor numbers.

[0100] To demonstrate the functional principle of the inventive method, the trichloramine concentration in the air of a swimming pool was determined. In addition, measurements of additional parameters were carried out using NO2 sensors, CO2 sensors, and particulate matter sensors.

[0101] The comparison of the measured values shows that these additional values behave or occur in a certain proportion to the NCl3 measured value and can therefore be used as surrogates.

[0102] Preferably, a calibration should be carried out on the basis of a suitable NCl3 measurement and further preferably repeated several times or regularly, for example with several different sensors, in order to further increase the accuracy of the values to be determined or measured.

[0103] Fig. Figure 1 shows the NCl3 values measured using a technology for photometrically determining the color change of a monolith due to its chemical color change. The measured values from an NO2 sensor are also shown. The graph also compares the values determined using a CO2 sensor.

[0104] These data were collected in a swimming pool (see Fig. 3) measured or determined in normal operation without using the WAPOTEC®SYSTEM by using a Nemo TC XT measuring device and the CVS data were exported to an Excel file via the Profil'air data management system before being output in a graphic as shown in Fig. 1 is shown.

[0105] The changes in the determined values result in graphs according to Fig. 2, which are slightly parallel and overlap, but in this case differ in value by a factor to be calculated.

[0106] After correcting these deviations to the NCl3 value by - value scaling and - temporal adjustment by a time span of 10 minutes forward results in an almost congruent graph, which can therefore be clearly used as a surrogate, since the deviation lies within a small tolerance.

[0107] Regarding the Fig. The following typical characteristics apply to the swimming pool 100 shown in Figure 3 and used for the test setup, which essentially comprises a swimming pool 10, a deck 30 and a spectator area 20: • Treatment process consisting of - Flocculation - Sand filtration - CO2 for pH correction - Calcium hypochlorite for disinfection • The water quality is controlled by a measuring and control system and the water treatment chemicals are usually added via separate dosing systems. • Water volume of the semi-Olympic swimming pool with deep end and vertical flow from floor inlet and overflow channel (220,000 USgal) = 833 m 3 • Water temperature (80°F) = 26 °C • Circulation capacity (498 USgpm) = 113 m 3 / h • Filter area (vertical sand filter with 38.5 ft 2 ) = 3,6 m 2 • Filtration speed = 31 m / h • Theoretical circulation time = 7,4 h

[0108] When designing the ventilation system, the hall volume and the various usable areas must be taken into account. An overview of this is provided Fig. 4.

[0109] Fig. 4 shows a plan view of the swimming pool 100 according to Fig. 3. The rectangular placeholders in the figure indicate the lengths of the pool and deck in meters. Pool 10 is 75 m long and 50 m wide. The deck surrounding the pool has a minimum width of 10 m. At its widest point, the deck width is 12 m. The average ceiling height in the swimming pool is 26 m.

[0110] The Fig. 3 and Fig. The swimming pool indicated in Figure 4 comprises the swimming area (so-called “wetted part”) and the spectator area with the following characteristics: • Total hall air volume (176,540 ft 3 ) = 5.000 m 3 • Air temperature (82°F) = 28 °C • Primary dehumidification system consisting of a combined fresh system and a continuous capacity of 5,509 ft 3 / min = 9.360 m 3 / h • Secondary ventilation system with air pressure control and an air capacity of max. 2,000 ft 3 / min = 3.398 m 3 / h • Theoretical circulation time = 0,53 h • Theoretical circulation time (with secondary ventilation) = 0,44 h • Required minimum air capacity according to ASHRAE 6.2.1 standard (5,509 ft 3 / min)= 9.360 m 3 / h

[0111] The ASHRAE standard is used for American swimming pool facilities.

[0112] Fig. Figure 5 shows the various usage areas and the resulting requirements. ASHRAE Guideline 6.2.1 stipulates different air changes per hour depending on the area within the swimming pool hall 100. To enable the supply of fresh air FL, a heating, ventilation, and air conditioning system 40 is installed in the area of the swimming pool hall 100.

[0113] With the help of a ventilation system 50, air can be exchanged in different areas of the swimming pool 100. In the spectator area 20, the guideline calls for 6-8 air exchanges LW2 per hour. In the area of the swimming pool 10 and the deck area 30, however, 4-6 air exchanges LW1 per hour are provided for, according to the above-mentioned guideline.

[0114] According to the guidelines, the air flow rate is calculated as follows: 48 cfm (cubic feet per minute) of air flow should be achieved per square foot of pool and deck area. This results in an additional 7.5 cfm per visitor. The measurements were taken in this air exchange environment, as described in Fig. 1 and Fig. 2 and Fig. 6 and Fig. 7 are shown.

[0115] A further embodiment of the invention results from interval measurements of NCl3 levels. Exposure values are measured over a longer period of time, e.g., 1 hour or 8 hours. This NCl3 exposure total can also be divided using surrogates and further calculated after the measurement based on the surrogate calculation. In other words, the NCl3 exposure total can also be divided into interpolated surrogates using the measured additional parameters and further calculated after the measurement based on the surrogate calculation.

[0116] For example, an exposure value of n ppb is measured over an observation period of 8 hours as a sum parameter.

[0117] The total value can be broken down into individual values of, for example, 10-minute intervals using the surrogate values and then used for different applications.

[0118] Individual or multiple values can always be used together as surrogates to increase accuracy or to compensate for measurement peaks or measurement errors.

[0119] The use of surrogate analysis values thus enables a breakdown of the measured values, including the display of peak values over a longer period. Furthermore, the conversion also allows the display of values beyond the reference period. To increase accuracy, reference measurements using the above-mentioned procedures for recalibration / adjustment are possible and advisable. This is made possible by appropriate automated calculations, particularly via electronic processors and storage media, thus allowing for particularly simple commercial application.

[0120] Fig.Figure 6 shows very impressively that particulate matter can also serve as a surrogate in the determination, in particular calculation, of a trichloramine content in the air.

[0121] How Fig. As shown in Figure 6, the amount of particulate matter (PM) and the trichloramine content in the air of a swimming pool were simultaneously measured. Particulate matter (PM) can be chemical reaction products and / or radicals.

[0122] Over time, the determined values change, as shown in the graphs of the Fig. 6. It can be seen that the measured values coincide, albeit slightly shifted parallel, but in this case they differ in value by a factor to be calculated, so that the amount of measured particulate matter can serve as a surrogate for calculating the trichloramine concentration in the air.

[0123] The Fig.The PM value shown in Figure 6 is multiplied by a factor of 10 with respect to the actual measured PM value. The graph of the Fig. Figure 6 also shows the NO2 and CO2 values measured in parallel or simultaneously. The measured values are proportional to the measured NCl3 value.

[0124] Thus, Fig. 6 clearly shows that NO2 and / or CO2 and / or particulate matter (PM) can be measured as surrogates for NCl3. The resulting factors regarding the proportionality of the measured NO2, CO2, and PM values to the measured NCl3 values can be used in a subsequent calculation and / or prediction with regard to an existing NCl3 value, so that a determination, in particular calculation and / or prediction, of an NCl3 value can be carried out based on a measured surrogate (e.g., NO2 and / or CO2 and / or particulate matter).

[0125] In Fig.Figure 7 shows another measurement example that the particulate matter (PM) values are congruent with the trichloramine (NCl3) measurements during most of the day. However, deviations can be observed, which are due to strongly fluctuating visitor numbers. Fig. 7, the measurement evaluation also shows the number of visitors in a swimming pool as 100.

[0126] At the beginning of the day, the measured trichloramine level is significantly elevated or excessive, as the dissolved trichloramine from the oxidation of the contaminants—attributable to the previous day's visitors—is initially released disproportionately with chlorine during the night after the pool opens. The first peak in the temporal progression of the trichloramine level is attributable to this effect.

[0127] This effect stabilizes quickly due to the circulation of a ventilation system, so that the trichloramine levels in the swimming pool air during the morning are extremely proportional to the surrogate values, making them very easy to compare and allowing conclusions to be drawn about the trichloramine content using the surrogate values. As the day progresses, increasing visitor numbers contribute to the introduction of additional nitrogen compounds into the swimming pool, with oxidation—the conversion of nitrogenous contaminants into chloramines and consequently trichloramine—proceeding slowly over a longer period of time.

[0128] Contaminants attributable to bathers, particularly the entry of urea and other nitrogenous compounds, can also be detected and displayed using KMnO4 measurements. Alternatively or additionally, combined chlorine can also be measured. Combined chlorine can be determined, for example, by measuring free chlorine and total chlorine, followed by a differential calculation.

[0129] The Fig. The fluctuating number of visitors in a swimming pool during the course of the day, as shown in Figure 7, therefore has an influence on the air quality as well as on the substances present and measured in the air.

[0130] As in Fig. 7, in addition to the number of visitors, a CO2 value is also measured. Fig.7, the measured CO2 value is given as the difference between a baseline CO2 value and the actually measured CO2 value. In this case, the baseline CO2 value is the minimum CO2 value, which is determined based on a CO2 value measured locally outside a swimming pool. This minimum CO2 value is influenced by changing external contamination. The actual CO2 value measured in the swimming pool is subtracted from this minimum CO2 value, so that the Fig. The difference value shown in Figure 7 is determined. This CO2 difference value, or CO2-min (ppm), shows, when compared to the pollution due to the number of visitors, that the values correlate.

[0131] The combination of visitor data, air and water quality parameters thus increasingly improves the accuracy of the surrogate values. Reference symbol 10 swimming pools 20 spectator area 30 decks 40 Heating, ventilation and air conditioning device 50 Ventilation system 100 swimming pool FL Fresh air LW1 Air exchange 1 LW2 air exchange 2 QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 2 652 494

[0014]

Claims

[1] Method for determining, in particular calculating, the trichloramine content (NCl3) in air, in particular in a swimming pool, wherein the measurement of at least one surrogate of trichloramine (NCl3) present in the air in addition to the trichloramine (NCl3) is carried out and the determination, in particular calculating, of the trichloramine content (NCl3) is carried out at least partially on the basis of the at least one measured surrogate value. [2] Method according to claim 1, characterized by that the at least one surrogate is carbon dioxide (CO2) and / or nitrogen dioxide (NO2) and / or nitrogen monoxide (NO) and / or a volatile organic compound (VOC) and / or particulate matter (PM). [3] Method according to claim 1 or 2, characterized by that when determining, in particular calculating, the trichloramine (NCl3) content in the air of a swimming pool, the number of people in the swimming pool is taken into account. [4] Method according to one of claims 1 to 3, characterized by that when determining, in particular calculating, the trichloramine content (NCl3) in the air of a swimming pool, at least one measured water parameter, in particular bound chlorine and / or UV254 and / or parameters which may represent similar organic contamination, is also taken into account. [5] Method according to one of claims 1 to 4, characterized by that for the determination, in particular calculation, of the trichloramine content (NCl3), an initial measurement of the trichloramine content (NCl3) is carried out at least before carrying out the determination, wherein the measurement of the trichloramine content (NCl3) is preferably repeated at regular time intervals. [6] Method according to one of the preceding claims, in particular according to claim 5, characterized bythat the measured trichloramine content (NCl3), in particular the initially measured trichloramine content (NCl3), is used to determine a factor with the aid of which a determination, in particular calculation, of the trichloramine content (NCl3) is carried out on the basis of at least one measured surrogate value. [7] Method according to one of the preceding claims, characterized by that the determined, in particular calculated, trichloramine content (NCl3) in air is used to control a water treatment plant and / or an air treatment plant, wherein the determined, in particular calculated, trichloramine content (NCl3) in air is preferably transmitted to a control device of a water treatment plant and / or an air treatment plant. [8] Method according to claim 7, characterized bythat the determined, in particular calculated, trichloramine content is compared with a previously defined trichloramine limit value and / or a previously defined trichloramine range and, if the previously defined trichloramine limit value and / or the previously defined trichloramine range is exceeded and / or undershot, a change in water treatment, in particular a change in the process or process combination of water treatment, and / or a change in air treatment is triggered with the aid of the control device of the water treatment plant and / or the air treatment plant. [9] Method according to claim 7 or 8, characterized bythat with the aid of the control device of the water treatment plant, the circulation capacity of the water treatment plant and / or the added quantity of at least one water treatment agent and / or the content of at least one water treatment agent and / or at least one treatment step in at least one device bypass is / are controlled. [10] Method according to one of claims 6 to 8, characterized by that the amount of fresh air supplied and / or the total circulation capacity of the air treatment system is / are controlled with the aid of the control device of the air treatment system. [11] Method according to one of the preceding claims, characterized by that the determined, in particular calculated, trichloramine content (NCl3) in air is used to control a dehumidification system and / or a heating device and / or a cooling device and / or a ventilation device. [12] Device for carrying out a method for determining, in particular calculating, the trichloramine content (NCl3) in air, in particular a method according to one of claims 1 to 11, wherein the device has a sensor unit and a computing unit, wherein the sensor unit has at least one carbon dioxide sensor (CO2) and / or a nitrogen dioxide sensor (NO2) and / or a nitrogen monoxide sensor (NO) and / or a NOx sensor and / or a sensor for detecting volatile organic compounds (VOC) and / or a particulate matter sensor (PM). [13] Device according to claim 12, characterized by that the sensor unit has a trichloramine sensor (NCl3). [14] A computer-readable storage medium containing instructions that cause at least one processor to implement a method according to any one of claims 1 to 11 when the instructions are executed by the at least one processor. [15] Use of a determined, in particular calculated, trichloramine content (NCl3) in air, in particular a trichloramine content (NCl3) determined, in particular calculated, according to one of claims 1 to 6, for controlling a water treatment plant and / or an air treatment plant, wherein the determined, in particular calculated, trichloramine content (NCl3) in air is preferably transmitted to a control device of a water treatment plant and / or to a control device of an air treatment plant. [16] Use according to claim 15, characterized by , that the circulation capacity of the water treatment plant and / or the added quantity of at least one water treatment agent and / or the content of at least one water treatment agent and / or at least one treatment step in at least one device bypass is / are controlled by means of the control device of the water treatment plant, and / or the amount of fresh air supplied and / or the total circulation capacity of the air treatment system is / are controlled with the help of the control device of the air treatment system.

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