Liquefied Petroleum Gases (LPG) | SAM-203

• Sample cylinder corrosion resistant with accessories: fittings, connectors, valves and armoured elastic tubing (G01-01).
• Sampling valve or by-pass sampler mounted adjacent to the pipe or mounted directly on the pipe
• Floating-piston cylinder

A suitable material is stainless steel; aluminium parts must not be used.

The most satisfactory sampling line is one equipped with two valves, (a control valve, and a vent valve) in addition to that at the product source and those on the container. Between valves a pressure relief valve must be installed, which must be vented to a safe place.

Gas cylinder (M10)

Sample containers must be equipped with two valves, fitted with an internal ullage tube to permit release of the container content as a liquid. This end of the container must be clearly marked. Sample containers without an internal outage tube are also acceptable; in this case alternative purging and venting system is required.

Sample containers for use under pressure must be pressure-tested and the maximum safe operating pressure must be marked on the container. Sampling operators shall ensure that the pressure rating of the container is suitable for use with the product to be sampled.

Please refer to your national legislation and guidelines on health and safety.

• Check the SDS or ADR if available.
• Pay attention to safety and warning signs.
• If no information is available or the information (labelling, hazard and safety symbols, documents) diverges from what you would expect you should treat the goods as dangerous. Consult your laboratory.
• You should be aware of and follow any health and safety instructions in the local risk assessment and/or safe working practices for the location where the sampling is to take place.
• Wear appropriate personal protective equipment. You must avoid contact by liquid LPG with the skin. Protective gloves and goggles shall be worn, and you must avoid breathing vapours.
• Hazardous situations may occur when opening pressurised containers.
• Hydrocarbon vapours vented during sampling must be controlled to assure compliance with safety and environmental regulations. Sampling should be accomplished in a well-ventilated place.
• Manipulation of LPG can give rise to static electricity. Equipment must be electrically grounded or earthed to the LPG tank before and during sampling operations.
• Sampling at extremely low ambient temperature or from cryogenic sources may require additional precautions to prevent sample cylinders from becoming full of liquid due to the sample warming to a higher ambient temperature.
• Precautions must be taken use, transport and storage to protect the integrity of the container from damage by using a protective cap on the valves so that accidental unseating of the valves or tampering with them is prevented.
• Any equipment used must be intrinsically safe.

Personal protective equipment

• Hand protection: gauntlets or gloves made of material resistant to hydrocarbons;
• Eye protection: safety goggles, masks or a face shield (if necessary);
• Body protection: safety clothing, chemically resistant, flame-retardant and antistatic type (if necessary);
• Safety helmets, ear protectors, and a safety belt (if necessary).

Great care is required to obtain a representative sample, especially if the material to be sampled is a mixture of liquefied gases. The following factors must be considered:

• Take samples of the liquid phase only;
• Avoid sampling from the bottom of a vessel;
• When it is known that the goods being sampled is composed of only one liquefied petroleum gas, a liquid sample can be taken from any part of the container;
• When the content of tank can be non-homogeneous, the uniformity can be achieved by circulating the contents prior to sampling. A waiting period of 30 min is recommended after circulation before sampling to permit settling of any aqueous material and to allow dissipation of any static charge that may have developed. When the material being sampled has been mixed or circulated until it is homogeneous, a liquid sample may be taken from any part of the vessel;
• If it is not practicable to homogenize a mixture to ensure uniformity, obtain liquid samples by a procedure which has been agreed with bodies involved.

Where the product is being moved using pipelines or other equipment, there may be diverter valves or by-pass samplers mounted on the pipe, that allow samples to be drawn at regular intervals determined by the moving speed and the total quantity of the consignment. The most important thing is to make sure the tip of the probe is in the central third of the pipeline.

Samples must be drawn during the whole time the lot is flowing past the sampling point to ensure that the aggregate sample is representative.

When sampling under flow conditions, the pressure in the line needs to be above vapor pressure to avoid two-phase conditions.

A composite sampler takes a small sample from the pipeline and injects it into a sample cylinder. If the sampler is connected to a flowmeter it is possible to take samples proportional to flow. All aggregate sampling cylinders have internal mixing devices.

• A liquid sample is transferred from the source into a sample container by purging the container and filling in with liquid sample, then providing approx. 20 % outage so that approx. 80 % of the sample remains. Sampling consist of:
  • Purging the sample transfer line;
  • Purging the sample container properly before sampling. Containers shall not be overfilled. There must be sufficient internal empty space to allow sample expansion.
  • Transfer of sample into container (gas cylinder);
  • Sample outage – allow excess liquid to escape and close the valve at the first sign of vapor. If no liquid escapes, discard the sample and refill the sample container.
• For sampling containers without an internal outage tube, an acceptable alternative procedure to use is weighing the sample according to this procedure:
  • Fill completely the sample container using slight overflow indication;
  • Without warming the sample, immediately weigh the container with sample on a balance, and record gross weight;
  • Carefully drain off liquid from the bottom of the vertically oriented container in an environmentally approved manner;
  • Then weigh the vented container, and using the tare weight of the container, estimate the outage of the sample in the container. Repeat the venting and weighing to obtain approx. 20 % outage of the sample.
• Containers must be checked for gas tightness (leakage test). After the excess liquid has been eliminated so that 80 % by volume of the sample remains, the container shall be checked for leaks e.g. by immersion in a water bath. If a leak is detected at any time during the sampling operation, discard the sample.
• Where immediate venting is not possible, for example inside hazardous locations, provisions must be ensured to prevent temperature increase prior to venting in a safe location, transfer to a larger cylinder, immediate analysis or other safe measures provided.
• Alternatively, sampling can be performed by using of floating piston cylinder: A hydrocarbon fluid sample is transferred under pressure from a source to a moving piston cylinder. The piston-type cylinder is designed to collect fluid samples by displacing a pressurizing fluid (usually an inert gas) at sampling pressure. The piston serves as a barrier between the sample and the inert gas. The method provides for a 20 % inert gas volume for safe storage and transport of the sample.
• Consult your laboratory to check if it is able to provide analysis of a gaseous sample.

• Fill in the sampling form. One copy should be attached to the samples and one copy should be kept for the record.

• Sample must be labelled to indicate the specific nature of their hazard, see the Health and Safety section;
• A copy of the SDS should always be kept with the sample;
• The sample container must be protected from damage during transport by using a protective cap on the valves;
• The sample is a material of which transport is governed by ADR rules or other relevant transportation rules; exemptions related to dangerous goods packed in limited quantities can be applied when combination packages are used (consisting of an inner and outer packaging not liable to break or easily be punctured) see the General principles section: Handling of samples: Transportation;
• During transport the sample cylinder must be protected from temperatures that could create overpressure of the sample;
• The transport vehicle must carry a suitable fire extinguisher.

• Sample must be labelled to indicate the specific nature of their hazard, see the Health and Safety section;
• A copy of the SDS should always be kept with the sample;
• The sample container must be protected from damage during storage by using a protective cap on the valves;
• Store in a cool and well-ventilated place away from heat sources and direct sunlight;
• Keep the container tightly closed and protected in order to prevent losses. Discard any samples in containers which develop leaks;
• Use a ventilated cabinet for flammables if available.