如何选择一款合适的颗粒计数器？

Any working system involving hydraulic oil, lubricating oil, engine oil, fuel and other oil media may have particle pollution and hazards. To solve, control or prevent these pollution and hazards, it is essential to regularly conduct necessary daily inspections of the oil sample pollution index of the oil system. So the question is, how to choose a suitable particle counter?

The method of oil testing

Firstly, it is necessary to determine the testing method, whether it is used online for on-site work or offline for laboratory analysis? Simply put, if there is a high demand for measurement results and it is often necessary to use a sampler to take samples from the site and bring them back to the laboratory for analysis, desktop instruments should generally be selected; If it is necessary to frequently change the testing location and conduct testing on different hydraulic systems, and the requirements for testing results are high, portable instruments should generally be selected; If the requirements for measurement results are not high, but continuous monitoring of the pollution control trend of fixed system oil or pipelines is needed, online instruments should generally be selected; If used for multiple experiments on hydraulic filters, it is best to choose a dedicated online particle counter.

Determine the type of oil to be tested

Understand whether the oil to be measured is a two-phase liquid (such as water ethylene glycol flame retardant hydraulic fluid), whether it is corrosive (such as phosphoric acid hydraulic oil)... The light blocking particle counter requires that the liquid to be measured is transparent and homogeneous. Any component that forms an optical interface, such as two-phase liquid, emulsion, liquid mixture, liquid sample containing water or bubbles, or foreign incompatible liquid, will be recorded as particles, resulting in measurement results that differ greatly from reality; In addition, if the liquid to be tested is corrosive, it is also necessary to understand in advance whether the sensors, pumps, pipelines, connecting joints, etc. of the instrument have corrosion resistance and other characteristics when selecting the instrument.

Determine the viscosity of the oil being tested

When the viscosity of the oil to be tested is too high (such as wind turbine gear oil), the built-in metering pump/plunger pump of the portable particle counter is prone to introducing bubbles or insufficient volume during the extraction of the liquid sample, which may affect the detection results. Generally, a pressure chamber (equipped with positive pressure assisted injection and negative pressure vacuum degassing functions) needs to be added. Different viscosities can be solved by adjusting different pressure values, or by combining heating or dilution methods to reduce viscosity; Ordinary online instruments (without built-in pumps) and desktop instruments (with built-in pressure chambers and air pumps) usually do not need to worry.

Other

Determine the grading criteria for oil testing and measure the size range of solid particles.

The particle counter based on shading principle is currently the most widely used type for detecting solid particle contamination in oil liquids. The light sources used in this type of instrument mainly include white light and laser. Among them, laser light sources have gradually replaced white light sources due to their advantages such as uniform light intensity, good stability, and strong anti-interference ability.

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How to choose a suitable oil-based liquid particle counter