Three sampling procedures commonly associated with engine oil sampling include: sampling a pressurized line before the system filter; using a drop tube in the dipstick tube; and procuring a sample midstream from a drain port while draining the engine.

三种通常与发动机机油取样有关的取样程序包括：在系统过滤器前对加压管道取样；在吸管中使用滴管；在排放发动机时从排水口获取样品。

Pressurized Line加压管道

Figure 1. Pressurized Line图1：加压管道

Sampling a pressurized line on an engine is fundamentally equal to sampling a pressurized line on any industrial forced lube system, and is the preferred method for engine oil sampling (Figure 1).

对发动机上的加压管道取样基本上等于对任何工业强制润滑系统上的加压管道取样，是发动机机油取样的首选方法（图1）。

Through the use of a pump, the lubricant is drawn from the sump and pushed through a filter, where it is then delivered to the required lubrication points. The goal is to install sampling hardware in the live zone at a turbulent point located past the pump and before the filter.

通过使用泵，润滑油从油箱中抽出，并通过过滤器推动，然后输送到所需的润滑点。目标是在泵过去和过滤器之前的湍流点安装取样硬件。

When sampling is required, the hardware is utilized while the system is in operation creating a representative, repeatable sample. Installing sampling hardware is beneficial to maintaining a closed system whereby the sample can be extracted without opening the system and compromising its cleanliness from exterior elements.

当需要取样时，在系统运行时使用硬件，创建具有代表性、可重复的样本。安装取样硬件有利于维护一个封闭的系统，这样可以提取样品而不打开系统和损害其对外部元素的清洁度。

Drop Tube滴管

Drop tube sampling is synonymous with used oil analysis. Unfortunately, many inconsistencies and fundamental flaws have been associated with this method. Drop-tube vacuum sampling is a simple, low-cost solution to procuring a sample for oil analysis.

滴管取样是常用油分析的同义词。不幸的是，这种方法存在许多不一致和基本缺陷。滴管真空取样是一种油分析样品的简单、低成本的解决方案。

However, many factors should be considered before using this method. For instance, to draw a sample the machine must be opened, therefore the oil is exposed to the environment. Opening a machine potentially allows airborne contamination to enter the oil and cause damage.

但是，在使用这种方法之前，应该考虑到许多因素。例如，要抽取样品，必须打开机器，因此机油暴露在环境中。打开机器可能会使空气污染进入油中并造成损坏。

The key to an effective oil analysis program is the ability to draw an oil sample from a specific location while the machine is in operation and under normal load. Unfortunately, using the drop tube method while the system is running poses several concerns.

有效的油分析程序的关键是能够在机器运行和正常负载下从特定位置抽取油样。不幸的是，在系统运行时使用滴管方法有几个问题。

For instance, the plastic tubing may be pulled into the system resulting in safety concerns for the individual collecting the sample. This method also requires a large fluid flushing volume; has difficulties in obtaining consistent samples from the same location; and has problems with sampling high-viscosity fluids. In other words, this method of sampling should be avoided whenever possible.

例如，塑料管可拉进入系统，导致取样的个人存在安全问题。这种方法还需要较大的流体冲洗体积；很难从相同的位置获得一致的样品；并且在取样高粘度流体方面存在问题。换句话说，应尽可能避免使用这种取样方法。

Theoretically, when using this method in conjunction with a dipstick tube, the location will always be in the same general vicinity. The existing variable is the depth that the tube is inserted into the volume of oil in the sump.

理论上，当将这种方法与量油计结合使用时，位置总是在附近。现有变量是管插入油箱油体积的深度。

To help address the issue of tube depth, a premeasured or graduated sample tube should be inserted to a known depth, which will narrow down the termination point of the tube to a reasonable area of variable location.

为了帮助解决管深度的问题，应将预先测量或分级的样品管插入一个已知的深度，从而将管的端点缩小到一个可变位置的合理区域。

Figure 2. Sample Tube in Crank Case Dipstick图2曲柄箱量油尺样管

Drain Port Engine Oil Sampling排水口机油取样

Another common sampling method involves capturing a sample of oil as it drains from the sump. The theory is that by capturing the sample midstream, after purging a large volume of oil (40 to 50 percent) from the sump prior to filling the sample bottle, the sample taken more closely resembles a sample representative of the system.

另一种常见的取样方法是在油从油箱中排出时取样。理论是，在加注样品瓶之前，从油箱中清除大量油（40%到50%），采集的样本更接近于代表系统的样本。

One problem associated with this engine oil sampling procedure is the difficulty of extracting the sample. A special accessory has been adapted to make this procedure easier, cleaner and more reliable (Figure 3).

与此发动机机油取样程序相关的一个问题是难以提取样品。采用了特殊附件，使此过程更容易、更清洁、更可靠（图3）。

The drain sample kit uses a small cylindrical oil container approximately five inches in diameter that contains enough volume to hold the contents of the oil sump. A special bracket is then used to hang off the rim of the container to hold the sample bottle in the center.

排水样品套件使用一个直径约5英寸的小圆柱形油容器，它包含足够的体积来容纳油箱的内容物。然后使用一个特殊的支架挂在容器的边缘，将样品瓶放在中心。

With the open bottle in place, the container is placed beneath the drain port and opened, forcing the initial flow of the oil from the sump to drain into the container. When approximately 40 to 50 percent of the volume of oil in the sump has drained, the container is repositioned for the flow from the sump to drain into the sample bottle.

打开的瓶子到位后，容器放在排水口下面并打开，使油箱的初始油流入容器。当油箱内油体积的大约40%到50%被排出时，容器被重新放置，以便从油箱流出的油流入样品瓶。

Once the sample bottle is full, the container is once again repositioned to allow the remainder of the oil in the sump to drain into the container.

当样品瓶装满后，容器将再次重新放置，以允许油箱内的剩余油排入容器中。

Although this system allows for cleaner sampling when taking a midstream sample, be cautious of data from samples taken from a drain port. This is due to the fact that bottom sediment, debris and particles (including water) enter the bottle in concentrations that are not representative of what is experienced near or around the area where the oil lubricates the machine components.

虽然该系统允许进行更清洁的取样，但要小心来自从排水口取样数据。这是由于底部沉积物、碎片和颗粒（包括水）进入瓶子的浓度不代表油润滑机器部件附近或周围的情况。

In addition, this method is performed when the oil is being replaced with new oil. This does not apply to trending the in-service oil under normal operating conditions. The drain plug sampling method should be avoided if at all possible.

此外，更换新油时采用此方法。这不适用于在正常运行条件下牵引在用油。尽可能应避免采用漏塞取样方法。

Figure 3. Drain Sample Kit图3.排水口取样工具包

There are always various methods and associated variables with every engine oil sampling procedure. To be successful, it is necessary to understand the limitations and variability of each procedure and assume the appropriate amount of accuracy with each.

每个发动机机油取样程序总是有各种不同的方法和相关变量。为了取得成功，有必要了解每个程序的局限性和变异性，并假设每个程序具有适当的准确性。

References

1.  “World-class Oil Sampling - It is Possible.” Practicing Oil Analysis magazine, July 2000.
2. Jim Fitch and Drew Troyer. "The Basics of Used Oil Sampling." Practicing Oil Analysis magazine. September 2004.
3. NAVAIR Document 17-15-50.1

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