Sampling methods for different types of goods

The following section describes the principles of sampling of products in the form of liquids, granules, powders, bulk or retail sale packages, etc. The procedures described below are applied for such products, unless other specific procedures are required for them.

This section covers the sampling of homogeneous liquid products at ambient temperatures.

If the products are non-homogenous due to their nature, the products must be homogenised by mixing, shaking, or circulation through liquid pumps, etc. prior to sampling. If homogenisation is not possible, a larger number of incremental samples must be taken at various depths to ensure that a representative sample is obtained.

Dipping vessels (Sampling tool L02-01, L02-02 and L02-03) may be used to draw the samples. The sampler is lowered through the hatch of the tank until it reaches the desired level, opened and kept in position until it is filled and then finally hauled up. A vacuum pump (Sampling tool L01-01) may also be used, if the depth from which the sample is to be taken does not exceed 4 m, and depending on the viscosity of the liquid. Equal quantities of upper, middle and lower spot samples should be taken. A sampler used for cross-level sampling can be also used to take samples from tanks. The incremental samples from all sampling spots/levels are collected in a mixing vessel, and after they have been thoroughly mixed an aggregate sample is created. The number of incremental samples to be taken is determined by the quantity of the aggregate sample to be obtained. Remember that impurities and/or residual water may be present on the surface of the liquid or at the bottom of the tanks.

The total capacity of a ship or barge for the transport of liquid cargo is usually divided into a number of independent reservoirs (sections, compartments), which may have different sizes. The sampling procedures and the formation of aggregate samples are the same as described for sampling from tanks. Independent samples are taken from each part of the tank. If we are certain that all tanks of the vessel contain the same product (with equal qualities), an aggregate sample can be formed for the whole vessel by combining the incremental samples taken from all tanks.

Railway and truck tankers can be considered as horizontal cylindrical tanks. If we are certain that all compartments of a railway or truck tanker contain the same product (of equal quality), an aggregate sample can be formed for the whole tanker by combining the incremental samples taken from all compartments. If it is not possible to draw representative samples from the top of a tank, sampling must be done at the time of discharge or charge (Sampling tool L06-01).

Small vehicle fuel tanks represent one volume.

Sampling may be carried out using a vacuum pump (Sampling tool L01-01), various pipette-type samplers (Sampling tool L03-01) or other appropriate samplers e.g. Sampling tool L04-01 or Sampling tool L05-01.

If samples are to be taken from only one barrel, the final samples are poured directly from the sampler into the sample containers. When a set of barrels are to be sampled and we are certain that they all contain the same product, incremental samples are taken from several chosen (or if necessary from all) barrels, which are then combined in a receptacle in order to create the aggregate sample.

Samples are taken directly from the fuel pumps using the filler nozzle. Prior to sampling, at least 4 l of fuel is discharged into a separate container in order to fill the pipe of the fuel pump with fresh fuel. The sample containers for the final samples are directly filled from the fuel pump or by using a funnel or an extension tube in order to prevent fuel evaporation. The sample containers should be filled slowly in order to prevent foaming. The sample container must not be filled to more than 80 % of its capacity in order to allow expansion due to heat. Depending on the type of fuels to be sampled, the sample containers may be made of metal, glass or plastic.

Samples are taken from the neck of the fuel tank using a probe-type sampler or a vacuum pump (Sampling tool L01-01). The samples are poured directly into the sample containers for the final samples. If a probe or a vacuum pump cannot be used for sampling, the samples are taken by other appropriate methods.

If possible, the most representative sample of liquid product transported in bulk can be obtained when they are being discharged or moved by gravity or using pumps, e.g. by using of Sampling tool L06-01. The samples must be drawn throughout the discharge or charge. As a minimum three incremental samples should be taken, at the start, in the middle and near the end of the discharge or charge, but you should take account of the total quantity of the consignment and the speed of movement when determining the number of incremental samples required and the interval between sampling. The aggregate sample is created by mixing the incremental samples. The final samples can be obtained from the aggregate sample.

This section describes the sampling of solid goods in the form of powders, coarse or fine particles, granules and other types of presentation typical of bulk products. Bulk products may be transported in packages or in the free bulk state (without packages). During transport and storage, such products may be packed in sacks, bags of appropriate sizes, etc. In the unpacked state, these goods may be transported by vessels and cargo carrier barges, on rail wagons, in lorries, etc. They may be kept in silos and on storage platforms.

Take note of the different batch numbers or production runs or production data when you take samples. You can take fewer different incremental samples when the marks and numbers on all packages are the same.

Overview of the amount of the consignment and the amount of the sample to be taken is specified in the sampling procedure cards for each product type. For goods not covered by a sampling procedure card this table can be used:

Number of packages	Number of packages to be opened for sampling	Amount of incremental sample	Amount of aggregate sample	Amount of final sample
1-25	1	Max 1 kg	Max 4 kg	0.5 kg
26-100	5	Max 1 kg	Max 4 kg	0.5 kg
More than 100	10	Max 1 kg	Max 20 kg	0.5 kg

You should ensure that the goods being examined consist of a single consignment. If there are several consignments, they must be identified separately. Check whether the goods to be sampled come from the same production batch. If there are different batches they must be sampled separately. An aggregate sample may be formed only from packages contained in the same consignment. Equal quantities of incremental samples are taken from different transport packages found at different positions in the transport vehicle or in the storage facility. They are collected in a mixing vessel and after they have been thoroughly mixed an aggregate sample is formed. The final sample is obtained using the sample division system.

Damaged packages should not be used as part of the aggregate sample. They should be set aside and may, if necessary, be subject to a separate examination and report.

Depending on the product and the transport method, different tools may be used for sampling: spear-type sampler (Sampling tool S01-01) for piercing the package, various zone samplers (Sampling tool S02-01), sampling trowels (Sampling tool S03-01), etc.

In case of bulk products transported in the unpacked state, equal quantities of incremental samples are taken from three or more positions throughout the bulk consignment. They are collected in a mixing vessel and after they have been thoroughly mixed an aggregate sample is formed. The final sample is obtained using the sample division system.

Overview of the amount of the consignment and the amount of the sample to be taken is specified in the sampling procedure cards for each product type. For goods not covered by a sampling card this table can be used:

Amount of consignment [in tonnes]	Number of incremental samples	Amount of incremental sample	Amount of aggregate sample	Amount of final sample
1-5	7	Max 1 kg	Max 7 kg	0.5 kg
5-500	2 per tonne/max 20	Max 1 kg	Max 20 kg	0.5 kg
More than 500	Max 40	Max 1 kg	Max 40 kg	0.5 kg

Where bulk goods are transported in wagons or lorries, samples are drawn from each wagon or compartment. In this case specific points are chosen to ensure a representative sample is taken from all parts of the consignment.

• Wagons or lorries up to 15 tonnes
  – 5 sampling points
  (middle and approx. 500 mm from sides):
• Wagons from 15 to 30 tonnes
  – 8 sampling points
  
  
• Wagons from 30 to 50 tonnes
  – 11 sampling points
  
  

If possible, the most representative sample of bulk goods can be obtained when they are being discharged or moved using conveyors. The samples must be drawn throughout the discharge or charge. As a minimum three incremental samples should be taken, at the start, in the middle and near the end of the discharge or charge, but you should take account of the total quantity of the consignment and the speed of movement when determining the number of incremental samples required and the interval between sampling. The aggregate sample is created by mixing the incremental samples. The final sample is obtained using the sample division system.

A retail package should be considered to be any pack specifically prepared for sale to an individual for domestic use.

Practical considerations may mean that you would treat a larger package as a retail package even though it is not classified as such in the Combined Nomenclature/TARIC.

This will apply particularly in the case of heterogeneous products where it will be necessary to take whole packages in order to obtain a representative sample.

Where the goods are found to be piece goods (e.g. timber, stone and ceramic products, metal castings or sheets or products such as electronic devices and apparatus) you should generally take whole items. If the size of the goods is large the representative piece of goods is divided (by appropriate tool such as saw, axe, and tongs) and sent to the laboratory examination. Large articles (such as metal tubes or sheets) can be tested immediately using a mobile laboratory or by means of mobile diagnostic equipment.

Sampling and analysis of waste can only give evidence of the composition of the waste. It does not provide evidence that the sampled material is considered to be waste, further checks or administrative research into the circumstances of the waste should be performed to confirm the classification as waste.

It is important to establish the purpose of the sampling before commencing:

• Will the sampling be used as evidence?
• Which rules may be violated?
• What will analysis of the sample prove?
• Will it be used as evidence that a shipment was in violation of the Regulation (EC) No 1013/2006 on shipments of waste.
• Will the evidence be used in court?

For specific environmental purposes a more detailed sampling procedure is necessary. See for these cases specific environmental sampling procedures or ask an expert for advice.

This section describes the sampling of miscellaneous chemicals, chemical products and preparations in gaseous form. However remember that certain chemicals should not be sampled because of their highly dangerous properties and should only be sampled by authorised personnel (e.g. a contractor).

Where the product is being moved using pipelines or other equipment there may be diverter valves or by-pass samplers mounted adjacent to the pipeline or mounted directly on the pipeline, which will allow samples to be drawn at regular intervals determined by the moving speed. Incremental samples are then collected in a sample cylinder (M10 Metal Cylinder Gas) over a period, for later analysis in a laboratory. Samples must be drawn during the whole time the lot is flowing past the sampling point to ensure that the aggregate sample is representative. Whichever probe you use, the most important thing to remember is to make sure the tip of the probe must be placed in the middle of the pipeline or, if that is not possible in the center, in 1/3 of the diameter of the pipe.

Examples of probes for sampling from pipelines (from EN ISO 3170)

You should ensure that the goods being checked consist of a single consignment. If there are several consignments, they should be sampled separately. An incremental sample is drawn from each container chosen randomly or systematically throughout the consignment. If a sample is to be taken from only one container it should be fed directly from the sampler into the sample container (M10 Gas Cylinder). When a set of cylinders are to be sampled and you are certain that such a set represents an identical lot, incremental samples should be taken from several randomly chosen cylinders, which are then combined in order to create the aggregate sample.

If a sample is to be taken from a tank it should be fed directly from the sampler into the sample container. When a set of tanks are to be sampled and we are certain that such a set represents an identical lot, incremental samples are taken from several randomly chosen tanks, which are then combined in order to create the aggregate sample. This way of sampling will only give a sample that is representative at one point in time only.

The sampling equipment (M10 Gas Cylinder) should be conditioned by rinsing with the gas to be sampled. The number of incremental samples is to be agreed to by all parties involved unless continuous automatic sampling is applied. If the composition is not completely homogeneous, homogeneity can be increased with a static mixer. The suitability of the materials used in a sampling system depends on the gas sampled. Generally it is recommended the use of stainless steel. Valve seats and piston seals must be made of a material (elastic) suitable for its intended use. It is recommended that the sampling cylinders used for corrosive gases are coated with polytetrafluoroethylene (PTFE) or epoxy resin.

Generally, the materials that come into contact with the samples must have the following characteristics:

• impermeable to all gases;
• minimum absorption;
• chemical inertia towards the constituents which are transferred.

Compatibility of different materials with the components of the gas is shown in the following table:

Material Gas	Stainless steel	Al	Ti	PTFE	Polyamide	Glass
Carbon dioxide	x	x	x	-	x	x
Carbon monoxide	x	x	x	-	x	x
Carbonyl sulfide	x	x	x	-	x	x
Helium	x	x	x	-	x	x
Hydrocarbons	x	x	x	-	x	x
Hydrogen	x	x	x	-	x	x
Hydrogen sulfide	-	-	x	x	x	x
Mercury	-	-	x	-	-	x
Methanol	x	x	x	-	-	x
Oxygen	x	x	x	-	-	x
Tetrahydrothiophene	-	-	x	x	x	x
Thiols	-	-	x	x	x	x
Water	-	-	x	-	-	x

Glass is a very inert material, but subject to breakage and unsafe for the sampling above atmospheric pressure. PTFE is inert but may have adsorbent properties. It is permeable, for example, to water, to helium and to hydrogen.

The handling and packaging of samples should be carried out in a well-ventilated place. When no information is available or the information (labelling, hazard and safety symbols, MSDS, documents) diverges from what you would expect you should treat the goods as dangerous. The containers must be made of a material suitable for the safe storage of chemicals and should be sealed to prevent leakage or the absorption of moisture. Sample containers must be clean and free from all substances which might contaminate the material being sampled. Glass cylinders must not be exposed to pressure. The cylinders must be labelled with the volume, pressure and test pressure. The cylinders must be capable of at least 1.5 times the working pressure. The cylinders and associated equipment must be inspected and tested periodically to ensure they do not leak. Please refer to your national legislation and guidelines on health and safety.

In general:

• do not use naked flames;
• do not smoke;
• do not use equipment and tools which can create sparks;
• do not use spark ignition engines;
• do not use equipment that operates at temperatures greater than the flashpoint of gas mixtures;
• do not use chemicals which may react violently with gas;
• ventilation must be sufficient to prevent the formation of a flammable atmosphere.