|
|
Contamination determination
The contamination control is fundamental to maintain the wholeness of all the system components: without this control the system can hardly reach the expected service life levels as contaminators affect the system integrity and unbalance the tolerances among the various components.
Indeed, a contaminated fluid is to be deemed as an “abrasive fluid” that can cause several faults, also depending on the contaminating particle size.
As a general rule, the most of the contaminator (70-80%) is made up of fine 5-15 µm particles. The action of such particles on circuit components can result in a tolerance increase, drainage increase, volumetric performance decrease, temperature increase or viscosity decrease. These effects can take very different times to occur, from a few hours to some hundred hours.
If the polluting particles are coarse, bigger than 15 µm, the effects can be more dramatic causing an immediate seizure and system stop.
The contamination by ultra-fine particles (micropollution) causes harmful effects in valve most delicate points, e.g. obstruction of tiny calibrated holes, early wear, etc.
Contaminations can cause: dirty, sedimentation, oxidation, impairment, strains, chemical attacks, corrosion, seizure, failure, abrasion, etc.
1) DETERMINATION OF THE PARTICLE NUMBER AND SIZE (classification according to standards ISO 4406 and NAS 1638);
2) GRAVIMETRIC DETERMINATION OF THE CONTAMINATOR DRY WEIGHT (per unit of flux or washed area);
3) MICROSCOPIC AND CHEMICAL ANALYSIS (by means of scanning electron microscopy with energy dispersion sound, to determine the CONTAMINATOR COMPOSITION, MORPHOLOGY AND ORIGIN).
Contamination determination and classification
It determines the particle size and number. According to these data, the sample contamination is classified according to standards: ISO 4406 and NAS 1638.
Gravimetric determination
The contaminator dry weight is measured per unit of fluid weight or per unit of washed area.
The contamination degree is given in terms of milligrams of contaminator in a litre of fluid.
Contaminator specification
The contaminator can be chemically and microscopically analysed , if necessary, by means of the scanning electron microscopy with energy dispersion sound analysis, in order to understand its composition, morphology and possible origin.
A metallic alloy is an aggregate of two or more chemical elements having metallic characteristics.
To come to know a metallic alloy and its properties, some analyses have to be carried out to determine the structure, the component percentage and quantity, as well as the specific characteristics of that alloy.
|
|
|
|
