Basic Oil Sampling Tips
Oil samples can affect your oil analysis results. That small 70 mL sample submitted to your lab represents all the oil circulating in the equipment. Here are a few simple tips you can take to ensure you get a good, clean sample, that is representative of the oil in your system.
1) Sample From The Same Spot
Take samples consistently from the same spot – it is best to sample from an active stream, pre-filter in the system, while the equipment is running and the oil is warm. Sampling from the same spot ensures consistency, otherwise, you may see widely-varying results.
While talking about sampling location, remember, never sample directly from the drain port. When sampling from a drain port, bottom sediment, debris, particles can enter the bottle in concentrations that are not representative of what is experienced near and around where the oil lubricates the machine.
Likewise, drop tube sampling can also cause wide-varying results for a number of reasons:
– The tube is difficult to control, and the end location is hard to predict and results in samples being taken from different locations each time
– Contamination is a concern – from the opening where the tube is inserted or from reused tubes
– The equipment should be shut down to sample safely, meaning production must be disturbed or oil sampling frequency may suffer. Particles will also begin to shut down compromising the quality of the oil sample.
Dedicated sampling valves make it possible to take oil samples safely, while the equipment is running, from the same spot, every time. This means that oil samples can be taken at any time since shutdowns are no longer necessary. Sampling, while the equipment is running, ensures that the sample is a direct representation of the equipment’s condition. Additionally, the oil sample is coming from the same spot in the active zone every time, away from the sediment and filters. Meaning that the sample pulled will contain hot information-rich oil that can be trended against previous samples to show the condition of your equipment.
2) Sample at Regular Intervals
Take samples at regular intervals. If you wait too long between samples, you are bound to see signs of wear that appear abnormal. Sample often enough and regularly so the lab can establish a good baseline to monitor change in your system. Make sure samples are taken at proper frequencies and that the frequency is sufficient to identify common and important problems.
3) Keep Clean
Use a clean, dry bottle. Don’t open the bottle until you’re ready to take the sample. Make sure it is clean and seal it quickly once your have the sample. Remember you’re taking a 4 oz sample that represents a system with hundreds or thousands of gallons of oil. Accessories should also be clean, and valves must be flushed before each sample. It is important to purge 3-5 times the dead space volume before obtaining an oil sample. Plastic tubing should not be reused to avoid cross-contamination between oils.
Consider new vacuum-charged sampling bottles. Vacuum charged bottles are ready to draw an oil or coolant sample in seconds with delivery going straight from the valve, or equipment to the sample bottle.
Label. Be sure to identify the exact oil viscosity or SAE grade in addition to the brand and product name. Include the type of equipment, the number of hours on the unit, the number of hours since the last oil change. The more accurate information you give your lab, the more precise analysis they can give to you.
Send in your sample ASAP. Don’t leave the sample sitting on a shelf. Send them in immediately and check your results when you get them.