to determine the concentration of harmful substances is necessary to begin to produce samples of air.This process is extremely important and painstaking.This is due to the fact that even with the most accurate analysis results produced properly bleed distorted.Because there are a number of requirements for the process:
- need to get a sample, which corresponds to the actual composition of the air;
- accumulate in the sample is desired amount of the desired substance to be detected in the laboratory.
sampling air depends on several factors:
- physical state of a substance in the environment (condensation aerosol, gas, steam);
- possible chemical interaction of a substance with the surrounding atmospheric environment;
- number of substances in the air;
- methods.
During research in the laboratory using different methods of air sampling.The most common - aspiration and method of selection of the vessel.
Aspiration
method is the most common method of hygienic practice.The peculiarity of this method is the aspiration.In other words, the air filtration test using special substances which are able to absorb a certain ingredient of all passing therethrough.This material is called the absorbent medium.Disadvantages of the aspiration method of air sampling:
- This is a very laborious process.
- takes a long time (about 30 minutes).During this period can occur an average concentration of a toxic substance.A desired concentration of the substances in the air changes too quickly.Methods of air sampling carried out by professionals.
selection in vessels
This method is characterized by its speed.It is used when limited to small volume test air and there is no need to accumulate the desired substance in the sample.Thus the selection and use a variety of container vessels: cylinders, bottles, syringes and gas pipettes and rubber chamber.This method of sampling the air is very sensitive and accurate.
In practice, a few varieties of aspirators.The simplest of them - water.The appliance for air sampling consists of a pair of identical glass bottles, which are pre-calibrated.These vessels can accommodate about 3-6 liters, closed with plugs, which come from two glass tubes.One long and reaches the bottom of the bottle, and the other - short, ending just below the cap.Long tubes connected to a pair of bottles rubber tube with a clamp.It joins a short absorber.When you open the clip, the water enters the empty container placed above the one in which is initially liquid.At this time, above the surface of water is vacuum whereby air is sucked through the analyzed absorber.The rate for such sucking from 0.5 to 2 liters per minute and the volume of air passed through the absorber, the same as the amount of water that has passed the way from the top to the bottom of the bottle.
This method is time-consuming and is one of the most difficult.Convenient to use elektroaspirator Migunova considered.This device combines the electric blower with a rheometer which is a glass tube flowmeters, two of which are needed to measure the velocity of air sampling, and the other two are designed for high speed.Low speed is from 0.1 to 1 L / min, and more - from one to 20 liters per minute.The lower part of flowmeters connected to fittings, removing the front of the device.These nipples attached rubber tubes with absorptive devices.Through this scheme, at the same time can be selected just four samples.The upper part has a handle valves flowmeter which similarly derived in a front portion.This helps to regulate the rate of air sampling.
principle of operation of this device is that during the switching network via the motor rotates the blower rotor.At the same time it lowers the pressure housing.And the air, the device is placed, passes through the nozzles.Then it comes out.Learning time spent on its passage through the aspirator and its velocity can determine the amount of air passing through the absorption device which is attached to the nozzle.Existing
absorbers designed to collect chemical impurities from the air by means of solid and liquid media.And sinks, and the environment for his chosen not by chance.This takes into account the aggregate state of the substances that pass the study.And also need to provide prolonged contact and absorption of the material environment.
If the test substance is a gas or vapor in the air in large quantity, the method of determining if a very sensitive, it is therefore necessary small amounts of air being analyzed.This requires cross-sectional sampling methods.For them, using rubber chamber, calibrated bottles and vessels that can accommodate from 1 to 5 liters, as well as gas pipette 100-500 ml.However rubber camera may be used only if the test substance does not respond accurately to the rubber.They air is not stored for more than three hours.It is pumped back by a bicycle pump.To study the air is transferred to the calibration bottle or other absorbent to an appropriate environment.
selection by sharing
When the air is filled with the investigated gas pipettes and bottles, such a method is called by the exchange.
air that lends itself to laboratory studies, is blown through the dropper or bottle many times.The pipette is filled with a rubber bulb, pump.This is possible with open terminals or taps if they are.Upon completion of sampling they close.In the case of bottle gauge, it is equipped with a stopper and two glass tubes.These outer ends are attached rubber tubes with clamps.Before the start of the selection of the clips are removed.And one of the tubes joined by a pump or a rubber bulb.Then the bottle is purged with air investigated many times.At the end of the sampling tube clips overlap.
vacuum method
indoor air samples are made using thick-gauge bottle.It is necessary to create it using a special vacuum pump Komovskogo.Analyzed air is sucked from the bottle to the residual pressure that ranges from 10 to 15 mm Hg.Then you need to close the clamp on the rubber tube.Disconnect the pump from the vessel.And at the end of the rubber tube inserted glass stick.In place of the sampling container is opened.She quickly filled the air through equality of pressure.At the end of the sampling clamp screwed, and to place the opening rubber tubes put a glass stick.
method of pouring
air sampling is performed with a pipette or a calibration gas bottle.They are filled with a special liquid, which should not react with the target substance and especially dissolve it.For these purposes are often used plain water.When this option is omitted, resorting to the use of saturated (hypertonic) solutions of sodium or calcium chloride.
the place of sampling the liquid is poured, and the vessel is filled with air under investigation.Then, cover the rubber tube with special clamps, and put the glass on the ends of sticks, or simply close both valves on the gas pipette.
Sanitary sample
These samples were collected for chemical analysis and determine the total dust in the breathing zone of rights and a half meters above.
studying air pollution due to industrial emissions, and determine the average daily maximum single concentration of harmful substances in the atmosphere.Sanitary air samples are usually taken up in the moment of greatest pollution from the windy side of the source.Take at least ten samples of all points and at regular time intervals.Sampling of the air takes about twenty minutes.With increasing distance from the source, from which comes the pollution (no more than five kilometers, more accurate analysis is simply impossible), the duration is also increased to 40 minutes.
To determine radioactive and carcinogenic substances sucked through the necessary large volume of air filters.Because in populated areas investigated elements are contained in very small quantities.In the process of sampling the air in large industrial enterprises to study the content of toxic substances (such as gases, vapors) or large amounts of dust occupies an important place point selection.In industrial premises or buildings unevenly distributed pollutants.The air environment is constantly and randomly mobile.For these reasons, devices for a sample of the atmosphere in the place where the workflow at a half meters from the floor.It is considered the level of the worker's breathing.During one shift, take three samples: the beginning, middle and end of the working day.During their capture must take into account the humidity and the temperature in the room.Absorption devices that are needed to produce the sampling of air in industrial plants, reminiscent of glass tubes, which are sealed at the top and sealed even with a pair of glass tubes.After a long tube enters the air analyzed.And it passes through the brief further to the blower through the rheometer.The lower part of the absorber is designed for absorbing liquid through which the test gas must be sucked.Air sampling of the working area is essential for normal functioning of the enterprise and to ensure working conditions for staff.In accordance with current legislation and labor protection requirements is a mandatory process.
gravity selection method
This method of sampling the air in the room or on the street based on the fact that dense particles that are suspended in it, settle under the influence of gravity.Probozabornik Durham - basic device, which is used for the gravitational sampling ambient air.The essence of his work is as follows.The holder of the device is inserted into a special slide that is covered with glycerine gel.He then left in the air for a day.The particles are transported by air flow, are deposited on the slide.Further, in the laboratory under the microscope determined the composition and amount of the particles.The results represent the number of particles that have settled on a square centimeter per day.Gravitational air sampling method inexpensive and simple enough, however, and it does have its disadvantages:
- results of the analysis may be inaccurate due to factors such as the direction, wind speed, precipitation and humidity;
- per day have time to settle a small number of particles;
- on the slide mainly large particles fall;
- samples collected by professionals, for this they require special equipment and aspirators for air sampling.
volumetric method
The essence of this method is that the particles which are suspended in the air, held up by obstacles set by its flow.Air samples in heavy industry needs to collect no less than once a year.In terms of the method used, such probozaborniki:
- Rotary.His collecting surface is covered with a special substance, then it rotates over time at the correct speed.The result of the sample with the help of this device is expressed by the number of particles that have time to settle down for the night in one square centimeter.This method eliminates the influence of wind speed and direction on the result of the analysis, thereby giving more accurate analysis.Academy of Allergology and Immunology recommends the use of such a device to find in air pollutants.
- Aspiration probozabornik can pass through the membrane analyzed the air filter with a given pore diameter.The collecting surface is necessary to settled on it particles of a certain size.This principle is the key to a spore trap Buharda where the collecting surface can be moved at a speed of about 2 millimeters per hour.This makes it possible to monitor how changing the concentration of particles in the test air.We have a wind vane device, but because the wind direction does not affect the final results.
Evaluation of the results of gravitational selection method can detect coarse particles (eg, ragweed pollen).The research purposes are used more powerful and accurate obemometrcheskie ways.
Research
pollution in accordance with applicable law takes air sampling.GOST 17.2.3.01-86 required for proper analysis and calculation errors.
In order to study the degree of air pollution in the Russian Federation have developed a special term - "maximum permissible concentration".To date, we identified the maximum permissible limits.Concentration in air pollutants shall be not more than five hundred substances.Air samples can control the situation.
Maximum allowable considered the most concentrated admixture of air, which refers to a specific period of time or periodically throughout the life of a person will not have a harmful influence on him (and long-term effects are taken into account) or on the environment.
In the case of high concentration of gas is carried out air breakdown voltage in this case is about 33 kV / cm.When pressure is increased and the voltage increases.
existing laboratories, research institutes and private qualified professionals, who with the help of modern appliances and high-tech devices to identify and remove harmful substances in homes, apartments, offices, plots, etc. Sampling of air is made workers sanepidemstantsii, and then testedstudies in the laboratory.
How to protect your home
If you begin to notice that one of your family members (or yourself) suffering from allergic reactions, for unknown reasons, and the invisible, then you need to analyze samples of air in the room.There are several methods.Ordinary dust, mold, radon or different pathogens in the air negatively impact on the health of people, especially young children.Sampling of the air necessary in case of allergic reactions and of other one of the family members.Methods that help to analyze the air in the premises:
- must install a carbon monoxide detector.This unit plays an important role and, without exaggeration, saves lives.To install this small unit is only necessary to wall outlets.If the sensor has issued a warning sound, so the apartment changed level of carbon monoxide.As is known, the gas is colorless and virtually odorless, and therefore part of the sensor is indeed very large, it can save your life.
- Another way to protect your home - an analysis of air quality in indoor radon.This is especially useful if the house is near the site of the concentration of uranium in the ground, which can lead to the accumulation of radon.Air samples in an apartment in this case should be carried out regularly.There are kits intended for chemical analysis for the content of radon in the atmosphere.They can be used independently.Install and leave them for three days.After this set, and is going to the lab for analysis and the verdict.
- You can also buy kits to test the air for the presence of mold spores.To determine whether the apartment fungus or mold, it is necessary to conduct a microbiological analysis of the air pollution.Usually resorted to this method, if the family someone suffers from allergies or sinusitis.Devices for the analysis, you can use your own.However, to get the results you still need to use the services of the laboratory.
