Taking representative samples is vital to accurate analysis. It is important that personnel taking samples are well trained and understand the importance of a quality sample.
For larger or more complex machines there may be a number of sample points possible, each potentially answering a different question about the system. This could be about the condition of the oil as it arrives to lubricate a key component, the wear debris being generated by a particular component, ingress of contaminants in specific parts of the oil system, filter efficiency and other specific information. As it is not practical to sample from every conceivable location a primary sample point needs to be chosen. This data can then be augmented by samples from the secondary sample points as and when required.
When picking a primary sample point be mindful of the following:
Remember that taking a sample is also an opportunity for a quick visual/hands on inspection of the machine and its environment and an oil level check.
Depending on the capacity of the oil system and the sample volume taken, make up oil may need to be added to the machine to avoid oil starvation. Regular sampling and replenishment will affect the concentration of wear metals and contaminants and over time may have a significant impact on the oil properties. By informing the lab of the volumes added this dilution effect can be taken into account while diagnosing the sample. It is nonetheless preferable and more economical to only remove the necessary amount to enable analysis and to top up with care.
Where a dedicated sampling point may not be available it is often possible to take a representative sample using a vampire sampling pump. We are able to supply these together with adapters to fit different bottle neck sizes. We can also supply suitable sampling tubing, which comes in 30m rolls. Vampire pumps are simple and robust devices and if handled carefully will last a long time. As part of the sale we include lifetime return to base servicing – once it stops performing simply send the pump to us with your samples and we will clean it and renew any O-rings that may need replacing. We would then ship the pump back to you with some sampling bottles, labels and overspill bags.
The following advice will guide you through using a sampling pump to draw samples.
Vampire pumps can also be useful to sample greases. Grease is normally pulled into the tube to a certain length and left there without reaching the bottle. The ends of the tubing can then be trimmed and sealed with tissue and insulation tape for transit.
Do not use pre-lubricated syringes as lubricant will contaminate sample.
Overall the procedure is similar to using the vampire pump as outlined above with points 3-7 being equally valid.
Draw the sample into the syringe then disconnect the tubing and transfer the oil into the sample bottles provided. Try not to fill bottles above ¾ line.
A variety of sampling point types and sampling equipment exists for different applications and operating conditions. Where possible, suitable sample points should be installed. This makes most sense at the commissioning stage for new kit, however can be also be done at a later date, especially for critical equipment and where a long service life is anticipated.
For pressure lines Minimess valves can be used. For safety reasons pressure should not exceed 500psi (3.4MPa) if Minimess valves are used. For higher pressure systems helical coils may be required. For low-pressure systems a vacuum pump with a Minimess adapter may be required. Information about such systems should be available online and through suppliers.