Oil sampling
– general instructions

general information

1. Sample container

Samples should be collected in sterile, clean glass or plastic containers (single-use containers) with a capacity appropriate to the scope of testing. Available capacities range from 100 to 2000 ml.

• lubricating, circulating and hydraulic oils – use plastic or glass containers.
• electrical insulating oils – glass syringe (DGA testing), aluminium container (physicochemical testing).

When using auxiliary accessories such as a vacuum pump and probe, it is recommended to use dedicated containers compatible with the vacuum pump. It is recommended to use containers provided by the testing laboratory.

2. Sample information form

Proper completion of the form is essential for the identification and correct interpretation of the test results obtained from the collected sample. Please accurately enter all known information in the appropriate fields of the form. For details, see the sample information form (click here to download).

3. Sample collection method

Sample collection should always be guided by the purpose of the analysis, and the sample should be representative. A representative sample is one that reflects the condition/quality of the oil circulating/lubricating within the oil system.

For routine testing to determine the technical condition of the equipment and the oil, samples should be collected according to the following principles:

• only from active zones
• while the equipment is in operation
• under nominal load and temperature conditions
• at points of turbulent flow (elbows, changes in flow direction)
• upstream of filters
• sampling from the oil reservoir should be a last resort, when it is not possible to collect a sample under the conditions described above.

In specific cases, the purpose of the analyses may require sampling from another location (auxiliary sampling points). For example, to assess filtration efficiency, samples should be collected both upstream and downstream of the filter; from the bottom of the oil reservoir – to check for the presence of free water.

4. Sampling repeatability

To ensure reliable trending, samples should always be collected:

• from the same location
• using the same method
• under the same conditions
• by the same trained personnel
• ensure that an incorrect sampling procedure does not become a source of sample contamination

5. Clean sampling line and flushing requirements

Ensure the highest possible cleanliness of the sampling components/accessories and flush:

• the sampling port
• the sampling device (pump, probe/tubing, portable sampling valve)
• the sample container
• ensure that dead zones are properly flushed; the required flushing volume is 5–10 times the volume of the dead zone

6. Basic workplace safety requirements

Before collecting a sample:

• familiarize yourself with the general occupational health and safety instructions applicable at the site where the work is being carried out
• familiarize yourself with the safety data sheet (SDS) for the substance being sampled
• use the personal protective equipment (PPE) required at the sampling location

Sampling from a sampling port

1. Prepare the necessary accessories:

• sample container with the sample information form + pen, or a smartphone with the dedicated application
• container for draining oil (usually a bucket is suitable; in some cases, a differently shaped container, such as a tray, may be necessary)
• cleaning cloths and a container for used cleaning materials
• optionally, a wrench for opening/closing the valve

2. Organize the work area

If possible, ensure sufficient space to work freely. The design of the equipment may require climbing onto the equipment or may force you to adopt an uncomfortable or non-ergonomic position during sampling.

3. Complete the sample information form

Enter all known information in the appropriate fields and label the sample container with the sticker containing the number and barcode (from the bottom section of the form). These steps may also be completed after sampling.

4. Thoroughly clean the end of the sampling port with a cleaning cloth

5. Prepare/place the container for draining/flushing the sampling port

Drain an appropriate amount of oil contained in the “dead zone” and repeatedly decrease and increase the oil flow. Establish a stable and safe oil flow through the sampling port.

6. Place the sample container under the sampling port and collect the required amount of sample

• do not manipulate the oil stream while filling the container
• do not allow the sample container to come into contact with the sampling port
• open the container immediately before sampling and close it immediately after filling. If there is any doubt about the cleanliness of the container, use the first portion of collected oil as flushing oil and discard it, then collect the target sample
• secure the collected sample in a zip-lock bag
• in dusty, humid or otherwise contaminated environments, open the container inside a closed zip-lock bag, fill the container by piercing the bag with the end of the sampling port, then close the container without opening the bag

7. Stop the oil flow and clean any residual oil from the sampling port

Place the used cleaning cloths in the designated container. Leave the work area at least as clean and orderly as it was before sampling.

Extraction using a vacuum pump

1. Prepare the necessary accessories:

• sample container with the sample information form + pen
• pump – make sure that the thread of the sample container is compatible with the pump thread; if necessary, prepare a suitable adapter
• tubing and a knife for cutting the tubing to the required length
• dipstick
• cleaning cloths
• container for used cleaning cloths and tubing
• appropriate wrench for opening/closing the oil reservoir

2. Organize the work area

If possible, ensure sufficient space to work freely. The design of the equipment may require you to adopt an uncomfortable or non-ergonomic position during sampling.

3. Complete the sample information form

Enter all known information in the appropriate fields and label the sample container with the sticker containing the number and barcode (from the bottom section of the form). These steps may also be completed after sampling.

4. Assemble the sampling set:

• container + adapter, if required + pump + tubing of the appropriate length
• ensure that an improper sampling procedure does not cause contamination of the sample or the inside of the oil system
• ensure that the pump is cleaned before each sampling
• remember that a single piece of tubing must never be used more than once
• thoroughly clean the area around the sampling point before opening the oil reservoir

5. Open the reservoir

Using the dipstick, insert the end of the tubing into the reservoir. The sample should be collected from the central part of the reservoir, close to the oil return point. The bottom of the reservoir, areas near the walls and the oil surface are potential locations for contaminant accumulation.

6. Collect the required amount of sample

If there is any doubt about the cleanliness of the container or tubing, use the first portion of collected oil as flushing oil and discard it, then collect the target sample.
Disassemble the sampling set and immediately close the sample container with its cap. Secure the sample in a zip-lock bag.

7. Close the reservoir

Place the used cleaning cloths and tubing in the designated container. Leave the work area at least as clean and orderly as it was before sampling.

Taking a grease sample

1. Remove the inspection covers of the rolling bearing or the grease fitting cover (if there are no inspection openings).
2. When using a syringe and tubing for sampling, cut approximately 10 cm of tubing. Attach the cut piece of tubing to the syringe.
3. Use the syringe to collect the grease, filling the tubing (8 × 1). Take particular care not to collect fresh grease; observe the sample being collected! After sampling, insert the bent tubing into the sample container.
4. Where a spatula can be used, collect the grease from a location as close as possible to the rolling elements. Do not collect fresh grease! After sampling, place the grease in the sample container; if possible, place the spatula in the container as well.
5. For trending wear parameters and grease properties, samples should always be collected from the same location.
6. To compare the test results with reference values, collect a sample of fresh grease from the fresh grease container or, if necessary, from the bearing after installation.
7. Label the sample.