Sample Time to Test Time

Hi Robin,

To answer the second question first, the lubricant testing in and of itself is neither predictive or proactive. It is the usage of the knowledge gained from the analysis that drives the maintenance to be either reactive, predictive or proactive. If for example the analysis determines a parameter to be out of spec and the decision is taken to simply change the oil, then that is more reactive than predictive. If the same situation held and the decision was to monitor the condition to see what the change rate and consequences were then that would be more in the relm of predictive maintenance. If however a single parameter was out of spec and it was known that that parameter would eventually cause harm, the proactive approace would be to design out that condition from reoccuring.....
Back to your first question, is there value in a 1 month old sample analysis? The simple answer is that it is highly dependent on the application. If this is an application that from the time a condition can be determined (through oil analysis) and the failure occurs is around 1 month, or less, then the answer to your questions is clearly no. If however the point of detection and the onset of catastropic failure (loss of function) is greater than 1 month then there is still value to recieving the analysis 1 month after collection. I think you are starting to see a trend to this logic. You need to determine the type of tyical failures associated with the equipment. And then design your analysis schedule around the failure indicators.

hope this helped.

Alan

Robin, the concept behind oil analysis is that it is a snapshot in time that can tell you the condition of the lubricant and somewhat of the machine it is operating in. Here is where personal preference comes in, do you want to look at a picture that is a month old or do you want to see the picture right away. It's kinda like going to the Dr. for blood work, do you want the results in 4 weeks or not. Regardless of the failure mode, or onset to failure an oil sample is only representative at the time it was taken, and not at a later date. Machine conditions are constantly changing due to operational factors. So I hope this has given you some additional light on the subject and as far as predictive or preventative I will let you draw your own conclusions to that.

As a rule samples should be sent to the lab as they are taken and not at the end of the month or when the batch box is full. See if your lab provides individual mailers or box up smaller batches for the lab.