February 15, 2010



OIL SAMPLING GUIDELINES

by David Doyle, CLS, OMA 1 & 2
Vice President & Operations Manager

There are a variety of manners in which an in-service oil sample can be obtained. Many times, choices are based on the availability of access points. Sampling can often be made easier and expedited with improved safety by installing sampling ports in strategic locations. Some equipment manufacturers provide factory installed sampling ports.

The best sampling point may not always be the most practical. In this case, the most important factor when considering a sampling location is consistency, which greatly affects the quality of the historical data in trending analysis. Below are sampling practices that may be employed for some common systems.

In-line Sampling from a Circulating System

Using a permanently installed sampling valve, such as the 1/8" NPT Push Button Valve, helps produce reliable test results. This valve must be properly mounted on an oil line facing downward. The installed sampling valve will also facilitate the sampling process.

• Make sure the oil is flowing and warm.
• Avoid sampling in dead flow areas where contaminants may settle.
• Areas with turbulent flow are best, such as bends.
• Return line sample locations after oil has gone through the equipment are best.
• Do not collect samples after the filter or directly from the filter.
• Flush port areas.
• Use new tubing.
• Use as little tubing as possible.
• Use pump in low flow or low pressure areas.
• Clean area around sampling port.
• Collect sample directly into sample bottle, do not transfer from intermediate container.
• Do not use funnels.
• Use extra care for samples requiring a particle count.
• The accuracy of the oil analysis depends on the quality of the information provided to the laboratory.

General Procedure

1. Unscrew dust cap from valve.
2. Depress the button on the valve.
3. Flush the line by allowing a few ounces to drain before taking the sample.TAKING
4. Place the empty new sample bottle under the valve discharge opening.
5. Fill the sample bottle.
6. Tighten the cap on the sample bottle to secure a tight seal.
7. Use certified clean bottles if collecting a sample for particle count from “clean systems.”
8. Screw the dust cap back on the valve.

Possible In-line Sampling Locations

  • Engine Oil: Filter mount on engine block, before filter inlet
  • Transmission: Filter head, before filter inlet.
  • Hydraulic: Manifold or return lines
  • Axle: Oil pump

Sampling from Reservoirs

Though in-line samples are optimal, sampling from reservoirs is acceptable. Using a vacuum pump with attached tubing will provide the best sample and facilitate the sampling process.

• Make sure the oil is flowing and warm.
• Sample through breathers or fill ports.
• Clean area around breather or fill port before opening.
• Use new tubing.
• Use as little tubing as possible.
• Do not collect sample from the very top or the very bottom of the fluid level.
• Collect sample from one-half to two-thirds into the height of the fluid level.
• Collect sample as close to the inlet as possible.
• Use new tubing.
• Use as little tubing as possible.
• Collect sample directly into sample bottle; do not transfer from intermediate container.
• Do not use funnels.
• Use extra care for samples requiring a particle count.

NOTE: The accuracy of the oil analysis depends on the quality of the information provided to the laboratory.

Sampling During Oil Drain

Acquiring a sample during an oil drain is not as optimal but may be the only method available. Care should be taken to ensure consistent sampling procedures and that samples are obtained in a safe manner.

• Oil should be warmed and recently circulated.
• Do not take sample when the oil has been cold and static.
• Do not take samples immediately after drain flow begins.
• Takes samples at mid-drain.
• Do not use a funnel.
• Do not empty oil and take the sample from a drain collection container.
• Clean bottle off before shipping.
• The accuracy of the oil analysis depends on the quality of the information provided to the laboratory.

NOTE: This method is not recommended for samples requiring a particle count.

ALS Laboratory Group provides a wide variety of sampling supplies and bottle kit material. Our technical and customer service staff can always assist with sampling material selection that will provide the easiest application for obtaining an in-service oil or coolant sample. Our technical field staff is always available to assist in helping our customers with determining sample procedures, materials, and frequencies in order to maximize the benefits of a testing program to advance maintenance practices and equipment reliability.

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