Machinery Lubrication

Machinery Lubrication March April 2014

Machinery Lubrication magazine published by Noria Corporation

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46 | March - April 2014 | BeNNett FItCh | NorIA CorPorAtIoN The methods and tools used to extract an oil sample are crucial for quality oil analysis. These would include sample valves, transfer tubing, suction devices and anything that facilitates transferring oil from its original live-zone loca- tion to the sample bottle while avoiding further contamination in the process. This article is the latest installment of a series of "anatomy" lessons within Machinery Lubrication magazine. In this issue, effective extraction tools for taking a representative oil sample will be discussed. Part 1 of this three-part series examined the important role an oil sample bottle plays in obtaining a representative sample. In the next issue, how to select sampling frequency and sample locations will be addressed. Access Methods Retrieving an oil sample from a machine can be challenging. Among the techniques used to accomplish this task include the tap/ drain method, drop-tube sampling and live-zone sample valves, which is the preferred option. Sampling from a drain port threatens the ability to obtain a representative sample because it is located where sediment or water collects due to stratification. This method also allows envi- ronmental contaminants to be introduced through external drain surfaces or via sample bottles without proper lids. Considered the least effec- tive way to obtain a sample, it should only be used if no other alternative is possible or if you are merely collecting the sample to analyze accu- mulated bottom sediment and water. Drop-tube sampling can provide a representative sample if it is performed correctly. However, the process has several risks. It requires a tube to be lowered from a fill or dipstick port through the headspace and into the sump cavity. Positioning the end of the tube is difficult to control, which does not facilitate a consistent sampling location. Another concern is that contaminants may be scraped into the tube as it enters the system. If drop-tube sampling must be utilized, be sure to direct the end of the tube to a location in the sump where turbulence and flow occurs, such as directly between the drain and suction lines. Like the tap/drain method, drop-tube sampling is far inferior to using a live-zone sample valve with the proper configura- tion and location. Installing a sample valve can help to maximize data density and minimize data disturbance. The sample obtained not only will provide the most representative information about the oil and the machine, including cleanliness, dryness, additive levels, wear parti- cles, etc., but also contain information that is uniform, consistent and unaltered in the process. ANAtomY of a representative oIl sample: Part 2 — sample extraction tools l u b r i c a n t s a m p l i n g lessoNs IN lUBrICAtIoN 1. Remove the sampling valve cap and clean the valve port. Use a pressure gauge to verify the unit pressure if uncertain. 2. Insert one end of the new tubing onto the sampling probe piece and the other end into the vacuum sampler so that it is just slightly below the vacuum sampler face. Tighten the knurled nut on the sampler. Tightly thread on a purge bottle to receive the flush fluid. 3. Connect the sampling probe to the sampling valve and purge 10 times the dead volume by pumping the vacuum sampler. Loosen the knurled nut (or depress the vacu- um-release button) to stop the flow of oil. 4. Open a sampling bottle without opening the plastic bag. 5. Tightly thread the sampling bottle onto the vacuum sampler (the hose end must puncture the bag). 6. Extract an oil sample by pulling the vacuum pump handle. Fill the bottle to no more than three-fourths capacity. Loosen the knurled nut (or depress the vacu- um-release button) to stop the flow of oil. 7. Unthread the probe from the sampling valve. 8. Unthread the sampling bottle from the sampler without opening the plastic bag. Thread the purge bottle back on the vacuum sampler. Draw waste fluid from the tube into the purge bottle. 9. Cap the sampling bottle without opening the plastic bag. Sampling Fluids at Atmospheric Pressure

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