Measurement of the Merit of Dispersancy of
In-Service Engine Oils with Blotter Spot Method
The requirement for on-line machinery and oil condition monitoring is becoming evermore apparent as maintenance costs increase and production capacity and equipment performance are maximized.
One of the primary functions of a lubricant is to preserve the cleanliness of a combustion engine's mechanical parts. The cleanliness of the mechanical parts is facilitated by "detergency" and "dispersancy" (DD) additives in the engine oil.
The dispersancy is the property that allows the oil to suspend and carry away "pollutants" of diverse sources such as soot from combustion, metallic particles from wear, corrosion of mechanical parts, and insoluble products resulting from the ageing of the oil, etc. Dispersant additives in oil prevent agglomeration and sludge formation by dispersing contaminants. With proper formulated oil, the soot will remain homogeneously suspended up to high concentration levels. When soot load reaches a critical limit for current condition of the oil, a sudden loss of dispersancy leads to rapid agglomeration and deposition of soot onto machine surfaces. Contaminants like water and/or glycol can quickly knock out dispersancy performance without an increase in soot load. Diesel engine condition monitoring requires increased focus upon measuring both soot concentration and dispersancy performance. Unlike measuring soot concentration where numerous options exist, measuring soot content and dispersancy performance is a real challenge to the oil analyst.
The DT100DL operates according to ASTM D7899. The instrument simultaneously measures soot and dispersancy. The results reported are combining soot content and dispersancy performance.
A dedicated method is under approval process. This test method could be an alternative to very long and expensive test which is the engine test like DV4TD - CEC-L-93-04 where the pistons and rings are rated.
Phase 1 - a drop of oil is injected on a filter paper
Phase 2 - the drop spreads on the paper
Phase 3 - the oil with contained particles penetrate into the filter paper. The oil that is properly dispersing soot and other insolubles produces an evenly graduated spot. Dispersion characteristics of the oil are judged by how far oil drop spreads, how big the central sooty area is and how homogeneous the opacity of the spot is. The opacity of the spot will provide information on the oil contamination level. Though this method has proven effective, individual subjectivity in readings oil spots affects the reliability of results. To help oil analysts taking most advantage of this valuable traditional technique the company AD systems in cooperation with a lab dedicated in Oil Conditioning Monitoring (OCM) has developped a modern automatic instrument DT 100 offering significant increase in accuracy and repeatability of measurements. This new technique removes all the arbitrary aspect of the manual method.
Complete OCM program with unique information on oil dispersancy
Dispersancy measurement and soot content quantification
Tool to make justified pro-active actions and maintenance planning decisions
Removes all arbitrary aspects of manual method
Evaluation of oil formulation
Performance of DD additives
Ideal for trend analysis in OCM programs and diagnosis on diesel engines
Lubricants performance at engine operation conditions
Lubricants compatibility evaluation
The DT100 takes a spot image with a built-in digital camera. In seconds, the software scans and analyzes all the different areas of the oil spot and automatically calculates the quantitative quality parameters of a motor oil in service. The DT100 has been designed to satisfy needs of OCM laboratories. It is an easy-to-use and robust analyzer equipped with enhanced quality and communication features. The spot images can be stored on USB storage devices and sent to local networks (LIMS) with an Ethernet interface. Versatile communication protocol is configurable for the specific requirements of each laboratory. The DT100 provides fully traceable electronic data storage eliminating the need for paper archiving. A laboratory technician can perform on-site calibration in minutes using a standard calibration tool supplied with the instrument. The DT100 complies with modern QA/QS laboratory practices.
The index of contamination (IC) is the concentration of insoluble soot loading in a diesel engine oil charge and is expressed as weight percent. Such contaminants cause a rise in the viscosity of system oil and may result in the formulation of sludge, which can lead to excessive component wear. The merit of dispersancy (MD) indicates the ability of the lubricant in a diesel engine to carry combustion contaminants in suspension. It is expressed as a number from zero to 100. Providing an adequate dispersancy level is maintained, the amount of insoluble soot that can be tolerated increases and the diagnostician can make informed recommendations to the vessel's engineer about the treatment of the remaining oil charge. The lubricant's inability to maintain the contaminants in suspension may lead to deposits accumulating in the bottom of the crankcase and cause problems with filtration and/or purification equipment.
MD = 0 = poor dispersion: the insolubles are all concentrated in the centre of the oil spot in the test; the residues are flocculated.
MD = 100 = excellent dispersion: the distribution of the insoluble on the filter paper is homogeneous.
The demerit points (DP) figure reflects the overall condition of the oil, as it is a combination of the IC and the MD derived from the calculation DP = (100 - MD) x IC. A low DP (0 or close to 0) indicates slight contamination and excellent dispersancy. A high DP (approaching 100 or more) indicates heavy contamination and/or a poor dispersancy
|Dispersancy(MD)||100 (good) to 0 (verypoor)|
|Contamination index(IC)||0.1 to 5%|
|Combined Performance Rating(DP)||0 (good) to 200 (very poor)|
|Duration of spot analysis||Few seconds per spot|
|Max spot diameter||Up to 45 mm|
|Positionning of the spot||Visual centering with guide|
|Imaging system||color CCD camera|
|Light source||Dual lighting - backlight and front light LED panels|
|Calibration of imaging system||Special calibration tool (delivered with the unit)|
|Results storage||Unlimited, depends on external USB storage device capacity|
|Spot image storagel||Color image in front light and B&W image in backlight|
|Data output||2xUSB, LAN connectivity by Ethernet RJ45, optional printer|
|Dimensions (mm)||305 x 487 x 390 (W x D x H)|
|Electrical||115 to 230V - 2A - 50/60Hz|