Sampling is an essential component in obtaining adequate data on the qualitative and quantitative characteristics of any sample. And it doesn’t matter whether we are talking about food products, raw materials for any production, the state of our environment, oil products or something else. In industry GOSTs, sampling methods are described in great detail, indicating the requirements for equipment and the procedure. Safety measures are also of considerable importance, especially if hazardous substances are investigated or they are in difficult technological conditions.
Oil sampling
The quality of oil and oil products play an important role for many types of production. Therefore, there are many methods for sampling oil, depending on the characteristics of its storage and transportation. The volume of the combined sample is established by the regulatory documentation for a particular type of product.
Methods of sampling petroleum products and oil| From tanks | The oil is settled for 2 hours and the settled water and contaminants are separated through the siphon valve in the lower position. If oil is under pressure in excess of 1.96 kPa, then depressurization of the tank is not performed. From a tank with a pontoon, the method of sampling petroleum products involves the use of a perforated column. |
| From vertical tanks | The combined sample in one step is taken by a stationary sampler according to GOST 13196, as well as using a perforated sampling tube. The lower sampling point is the cut-off level of the nozzle for receiving and distributing in its lower part or 250 mm from the bottom of the tank (if we are talking about petroleum products). The method of sampling in accordance with GOST also involves taking samples pointwise. To do this, they are taken from three levels: upper (250 mm below the surface of the oil), medium (from the middle of the height of the oil in the tank), lower. The combined sample is formed by mixing point samples from three levels in a ratio of 1: 3: 1. At the request of the customer, the number of spot samples can be increased, they can be taken every 1 m of the height of the oil in the tank. In this case, the combined sample is formed by mixing the same point volumes. |
| From horizontal tanks | Separate spot samples taken from horizontally placed cylindrical tanks, the diameter of which exceeds 2.5 m, are taken in three levels, as well as from vertical. But the combined sample is mixed from point in a ratio of 1: 6: 1. If the diameter of the tank is less than 2,500 m (or more than 2.5 m, but it is only half full or less), then methods for sampling oil and oil products include taking samples from only two levels: from the middle and lower. The combined sample in this case is made up of a ratio of the middle and lower levels in a ratio of 3: 1. If the height of the oil level is less than 0.5 m, then only one sample is taken from the lower level. |
| From trench type tanks | Sampling is carried out with a portable sampler from three levels: upper, middle and lower, corresponding to values of 0.93; 0.64; 0.21 product volumes (count down). The ratio of point samples for compiling the combined is 1: 3: 3. If petroleum products have significant differences in density (more than 2 kg / m3), then seven levels are used to select point samples, which correspond to 0.93; 0.78; 0.64; 0.50; 0.36; 0.21; 0.07 volumes of oil. The combined sample is compiled by mixing equal in volume of individual point samples. |
| From rubber-fabric tanks | This method of sampling petroleum products involves the use of a metal or glass tube or durite hose from a level located at a distance of 50 mm from the bottom of the tank. |
| From underground mine storages | If the storage facilities are located in rocks having a positive and negative temperature, then sampling is carried out through a vertical trunk. The determination of the sampling level and the conditions for compiling the combined sample are similar for horizontal tanks. If there are several trunks in the storage, then a common combined sample is formed by mixing equal volumes of combined samples of all trunks. |
| From underground storages obtained by leaching rock salt deposits | An oil sample in this case is taken from a sampling valve, which is installed on the pipeline, in the process of pumping part of the product to an external tank. First, the annulus between the individual columns, which are filled with brine and oil, should be flushed by pumping oil to the above-ground tank. The volume of flushing oil should be equal to five times the volume of the annulus. A single spot sample is taken at the end of the wash. |
| From ice storage | The method of sampling in oil in this case will depend on the geometric shape of the reservoir. But the choice of point sampling levels and the proportion for compiling a combined one are based on recommendations for vertical or horizontal repositories. |
| From bulk vessels | If the height of the oil level in the tank of a bulk vessel exceeds 3 m, then point samples are taken by a portable sampler at three levels: upper (0.25 m below the surface layer of oil), middle (corresponding to the middle of the height of the oil column) and lower (0.25 m above tank bottom). The combined sample is prepared by mixing samples of three levels in a ratio of 1: 3: 1. If the height of the oil level in the tank is 3000 mm or has a lower value, then point samples are taken only from two layers: middle and lower. The combined sample is prepared by mixing samples of two levels in a ratio of 3: 1. |
| From railway and tankers | According to this method, sampling is carried out from a level corresponding to 1/3 of the diameter from the bottom of the tank, as well as from the bottom. If there are several tanks containing one type of oil of the same brand, then a sample is taken from every fourth tank, but not less than two. In this case, the combined sample is formed from mixing point samples in volumes proportional to the amount of oil in the tanks. |
| From barrels, cans and other shipping containers | One single sample of the product is taken from each packaging unit. The procedure is performed where there is no dust and precipitation. Liquid petroleum products should be mixed before sampling according to the method of GOST. For this, barrels with contents inside roll for at least 5 minutes. The liquids of cans, cans and bottles are mixed by shaking for five minutes or using a special mixer. You should also clean the surface of the container near the plugs and caps immediately before opening. Liquids are taken with a sampling tube, by lowering to the bottom of the container and closing the upper hole with a finger when removing it. Maze-like petroleum products are taken for analysis with a screw or piston probe, having previously removed a 25 mm thick layer of substance from the place of immersion. Fusible petroleum products, hardened in a barrel or bag after filling, split with a knife, chisel, ax or other sharp object. One of the breakaway pieces and taken for analysis. A sample of solid oil from a bag or box filled with tiles or pieces is taken in the form of one whole piece. Powdered oil is selected with a dipstick by immersing it to the full depth of the container. |
| Unpackaged petroleum products | If fusible petroleum products are molded in the form of blanks, then for every 100 castings they take a piece of one of them, but at least 10 pieces should be taken in each batch. If they are not molded, then one piece is selected from each ton of product with a shovel, but at least 10 pieces must also be selected from the batch. The combined samples are made by chipping from each sample three pieces of equal weight and mixing (not fusing). |
Oil sampling from the pipeline
This operation is performed by a stationary sampler. For this, sampling tubes must be mounted on the dispersant body. According to this method, sampling for analysis is carried out only when pumping oil. In this case, the fluid velocity at the inlet to the intake device should be equal to its average linear velocity in the pipeline in the same direction.
With the automatic sampling method, the combined sample is composed of a point volume of 1-10 cm 3 and a quantity of at least 300. Their exact number depends on the time and volume of the pumped liquids.
The manual method takes only point samples of petroleum products. At the same time, equal amounts of product are extracted at equal intervals of time and equal volumes of pumped liquids. A pooled sample is made up of equal volumes of spot samples.
Types of Samplers
Portable for liquid petroleum products or petroleum. They must be fitted with lids or corks that provide tightness, but easy opening in order to be able to take a sample at a certain level. Their mass should be optimal for immersion in the sample. Before each use, the samplers are inspected for cracks, gasket and cap defects, dirt or traces of moisture. Wash samplers after each use. After taking liquid samples, they are cleaned with detergents and rinsed with unleaded gasoline. The devices are cleaned of residues of oily-like oil products with a solvent and hot water. Portable samplers are stored in special cases or covers in a dry place.
For a manual method of sampling from a pipeline. Their main nodes are:
- Side intake device. It must be strong enough to withstand the pressure of the oil flow in the pipeline.
- Locking device. It can be manual (tap for sample transfer) and automatic.
- Sampler. It is made of materials resistant to oil products.
In automatic samplers, the locking device is actuated by an electric, pneumatic or electromagnetic actuator. To obtain a given sample after a certain period of time, a regulator is used, which is included in the work with the start of pumping.
Sampling procedure
Before sampling by a stationary sampler, liquid excluded from the sample system is drained from its system. Its volume must be equal to at least twice the volume of the system in a stationary sampler. The procedure for sampling oil and oil products from reservoirs and tanks:
- measured fluid level;
- calculated levels for the extraction of point samples;
- the closed sampler (its opening for filling) is lowered to a predetermined level;
- the lid or cork opens, the sampler fills and rises.
If it is necessary to take samples at several levels, then the selection is made from top to bottom sequentially. If you want to take a bottom sample, then perform the following operations:
- the sampler is lowered and mounted on the bottom of the tank;
- the plug from the nozzle is removed and aged until the sample is filled;
- the filled sampler rises and the sample merges into the sampler.
A pooled sample is compiled immediately after all point samples have been taken. To do this, they are mixed and take the specified volumes, which merge into one vessel.
Sample packaging and storage
All rules and methods for sampling include operations such as packaging, labeling and storage of samples. Packing samples of liquid petroleum products consists of mixing them and pouring them into dry clean glass bottles. Samples of solid petroleum products are packed in a plastic or cellophane film, or thick paper.
Labeling of samples is carried out using labels affixed to bottles, jars or bags, which indicate their number on the register, product name or brand, supplier, tank and lot numbers (tanks), date of sampling and shelf life of the sample, standard or Technical specifications for the oil product, positions and surnames of the persons who made the sampling and sealing of the sample.
Shelf life of selected samples| Purpose of storage | Shelf life |
| In case of disagreement in the evaluation of the sample | 45 days from the day of shipment |
| For customer representative | 3 months |
When transporting: - through the oil pipeline - other means of transport | 25 days 45 days |
For export: - oil - oil products | 3 months 4 months |
Meat sampling
As for other perishable food products, the GOST sampling method provides for the immediate study of samples taken. They are transported to the laboratory in the same thermal state as at the time of sampling.
Samples for analysis are taken from each carcass to be examined, or part of it, from the following points:
- 4-5 cervical vertebra near the incision;
- scapula;
- thigh (thick parts of the muscles).
A sample of the carcass, its part or offal is taken in a single piece, the mass of which should be 200 g or more. If you want to take a sample of the frozen product, then sampling methods involve preliminary defrosting.
Each sample taken is packed in parchment, cellulose or plastic film and supplied with a label indicating the name of the product and the number of the carcass (part thereof). According to the method of sampling from meat, collected and packaged samples are accompanied by a document indicating:
- date, time, name and address of the enterprise, as well as the place of sampling;
- type of meat, offal;
- sample identification number;
- the reason and purpose of the test;
- signatures of the person who selected and sent the samples.
Grain intake
For many products, not only sampling methods are important. Acceptance rules and the type of packaging are also of considerable importance. Grain can be transported in bulk, as well as in shipping containers and consumer packaging. In addition, each batch must be accompanied by documents in which the following information is indicated:
- the date of execution of the accompanying document ;
- name of the sender and station of departure;
- name of the culture, as well as its place of origin;
- Grade, class, type and subtype of grain;
- lot weight;
- number or name of the vehicle;
- invoice number;
- the name and address of the recipient, as well as the destination station;
- the results of previous analyzes of the quality of culture according to the available regulatory documentation;
- Signature of the person issuing the shipping document.
At the same time, acceptance rules and grain sampling methods allow the sender to issue one such document at once to several identical lots of grain, provided that they are delivered within one day. As well as several batches of the same quality accepted from one manufacturer within one day, they are considered one batch.
On the contrary, if, according to the results of visual inspection and comparison of point samples, the batch is not uniform, then it is separated and individual accompanying documents are issued .
Grain sampling
This procedure can be performed in various conditions (fixed or moving parties) and various types of means (manual or mechanical). Equipment is selected, focusing on the volume and weight of the sample, as well as the type of food product. Sampling methods require the quality of prepared instruments. They must be clean, dry, free from odors, free from pests and made from materials that cannot contaminate the grain.
So, the methods of grain sampling in accordance with GOST provide for the use of the following equipment for sampling:
- mechanical, pneumatic sampler and probes of various designs that do not injure grain;
- non-automatic scales (absolute error of not more than ± 0.01 g);
- scales up to 20 kg non-automatic (absolute error not more than +25 g);
- buckets with a capacity of at least 200 cm 3 ;
- dividers and trims;
- laboratory scoops;
- containers for placing samples.
Grain sampling| From cars | The sample for research is taken in this case by a sampler or probe manually. The number of spot samples depends on the length of the car body. If its length does not exceed 3.5 m, then samples are taken at four points. If 3.5-4.5, then in six. If the body length exceeds 4.5 m, then samples are taken at eight points. If samples are taken with a mechanical sampler, the sample is collected over the entire depth of the poured grain. With a manual probe, only two samples are taken - in the upper and lower layers. In a road train using this method, grain sampling is performed in each body (trailer). |
| From embankments in warehouses and on sites | If the height of the embankment is less than 1.5 m, then point sampling is carried out with a manual probe. If the height of the embankment of grain exceeds 1.5 m, then this procedure is performed with a probe on which the rods are screwed, or with one of the multi-level samplers. Before taking grain samples, the surface of the embankment is visually divided into equal sections with an area of about 200 m 2 . 1 ( ) . ( 500 ), , 100 2 . - , . |
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| From silos of elevators and warehouses with inclined floors | In this case, grain samples are collected when it is released from the silo or a separate section of the warehouse. |
| Out of the bags | From sewn bags with this sampling method provides for the collection of grain samples with a bag probe at three points. Insert the probe groove downward towards the middle part of the bag, and then rotate 180 ° and immediately remove it. The resulting hole is closed, performing crosswise movements with the tip of the probe, which leads to a shift of the threads of the bag. |
| Compilation of the combined sample | All collected point samples are poured into a clean container that is not affected by pests, which does not affect the quality of the grain. A label with the name of the culture and the number of the warehouse or transport, the mass of the batch and sample, the date of sampling and the signatures of the officials is put in it. |
| Daily Average Formation | Acceptance rules and sampling methods allow the preparation of an average daily sample, provided that several automobile batches of grain from a single supplier with uniform quality were received during the operational day. Homogeneity is established organoleptically and according to the results of testing for humidity and contamination. To form an average daily sample, a clean, airtight container is used, which indicates the name of the supplier, culture and variety, as well as the date. |
Microbiological analysis of water
It is no secret that microorganisms are living organisms. In an aqueous medium, they form a suspension capable of changing. Sampling is performed for various purposes, including:
- determine whether water quality meets regulatory requirements;
- characterize the level of water pollution by microorganisms with the definition of such characteristics as randomness, fluctuation in the level of pollution, cyclicity;
- identify the source of pollution.
The number and frequency of sampling for microbiological analyzes according to the methods in GOST are different and depend on the purpose of the study and the level of contamination. If the content of microorganisms in the ode is significantly higher than normal (or, conversely, much lower), then a minimum number of samples will be required. But if the level of microbiological pollution of water is close to the established norm, then additional tests will be required.
Sampling methods for microbiological analysis suggest that the sampling points for analysis are determined depending on the objectives. So, if you need to explore drinking water in centralized water supply systems, then you must take a sample at the point of water supply to the distribution network, as well as in dead ends, stagnant zones, in elevated areas and in low sections of the distribution network, etc. To study surface water water bodies, samples are taken within the boundaries of the settlement, at the water intake, etc. If the purpose of the analysis is to control the technological regime of treatment at the water treatment station, then samples are taken before and immediately after the water arrives at each stage of technol cal process.
Water Sampling Requirements
If at one point water is taken for different analyzes, then the sample for microbiological contamination is taken first. In this case, aseptic conditions must be observed: hands must be clean, gloves sterile, the container is sealed and free from dust and spray.
Dishes and equipment for sampling should be made of glass or other materials that do not affect the vital activity of microorganisms. The use of plastic containers as disposable laboratory glassware is allowed.
In accordance with GOST, water sampling methods and preparation require the sterilization of containers to collect samples. To protect them from all kinds of contamination, packaging in aluminum foil, paper or bags is required. Sterilized equipment must be labeled (date of sterilization) in order to keep track of the established shelf life.
Microbiological water sampling| From backbone networks | Samples are taken through special taps installed on the main distribution networks or areas close to the main ones. At the same time, the length of the conduit to the tap through which sampling is carried out should be minimal. If it is not possible to install special taps to check the quality of water in the main network, then taps inside the building are allowed. But for this they should be disinfected by flaming, and all kinds of nozzles, nets, etc. should be removed. After sterilization, the valve must be fully opened to organize the flow of water with a maximum force of 5-10 s, and then reduce the pressure by half and rinse at least 10 min |
| From the house network | Before carrying out the water sampling procedure, all nozzles are removed from the tap, the tap is flamed and the water is drained to remove the effects of disinfection. |
| From consumer tap | In cases of outbreaks of infectious diseases in order to identify sources of microbial contamination, a study of the water from the consumer's tap is carried out. In this case, all devices and nozzles on the crane are taken into account and are not removed from it. It is forbidden to disinfect the tap or drain the water before taking water samples. |
| At water treatment plants | At the stations involved in water treatment, as well as in reservoirs in which reserves of drinking water are stored, special taps should be installed at each outlet pipe to take water samples. They must be labeled, kept clean and suitable for sterilization by flaming. To control coagulation, filtration and other stages of water treatment, samples are taken at the inlet and outlet of the treatment devices. |
| From wells and wells | If a stationary pump is installed in the water supply system from a well or a well, then there must also be a metal tap (or some kind of outlet). Depending on the purpose of sampling, the pump must first pump up to five times the volume of water in the water point. If it becomes necessary to take a sample from an unused well, a temporary pump or other water-lifting equipment is installed. In this case, samples are taken at the beginning of pumping (to check the quality of water in the water point) and at the end of pumping (to determine the quality of water directly in the aquifer). If the well is gushing, then a water sample is taken from its mouth. |
| From swimming pools | If water samples are taken from swimming pools to check the quality of the incoming water, to evaluate the performance of filters or disinfection, then liquid samples are taken from sampling valves that are cut close to the pipes. If it is necessary to assess the quality of the water in the swimming pool, then samples are taken 10-30 cm below the surface at two points. Usually, for this purpose, they choose places opposite the drainage hole in the deep and shallow part of the pool after changing swimmers. In this case, sterility rules must be observed. |
| Recreational waters | Water in rivers and lakes in places intended for bathing people is estimated by the results of a series of samples throughout the bathing season. It is important to adequately select water sampling points for analysis. They should be located in the most popular places for bathers or in the supposed places of the greatest pollution. Samples are preferably taken with a special bathometer. It is allowed to use a clean sterile container, which is introduced to a given depth upside down. |
The capacity of the container intended for sampling should be adequate to the volume of water required to perform all microbiological analyzes. Often it is 500 cm 3 or more.