Filtration in brief - UFI HYDRAULIC - #1

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Contamination Control in the hydraulic systems is a very wide and complex matter; the following is just a short summary. Our Customer Service is at your disposal for any further information. The function of the fl uid in the hydraulic systems is transmitting forces and motion. In view of a reliable and effi cient operation of the system, it is very important to select the fl uid considering the requirements of the system and the specifi c working conditions (working pressure, environment temperature, location of the system, etc.). Depending on the required features (viscosity, lubricant capacity, anti-wear protection, density, resistance to ageing and to thermal solicitations, materials compatibility, etc.), the proper oil can be selected among a number of mineral oils (the most popular), synthetic fl uids, water based fl uids, environmental friendly fl uids, etc. All the hydraulic fl uids are classifi ed according to international standards. Solid contamination is recognized as the main reason for misfunctioning, failures and early decay in hydraulic systems; it is impossible to eliminate completely it, but it can be well kept under control with proper devices (fi lters). No matter which fl uid is used, it must be kept at the contamination level required by the most sensitive component used on the system. HOW THE CONTAMINATION IS MEASURED The contamination level is measured by counting the number of particles of a certain dimension per unit of volume of the fl uid; this number is then classifi ed in Contamination Classes, according to international standards. Measuring is made with Automatic Particle Counters that can make the analysis on line (through sampling connectors put on the system for this purpose) or from sampling bottles. Measurations and sampling of the fl uid must be done according to the specifi c ISO norms, to attest their validity. The most popular standard for Contamination Classes in the hydraulic systems is ISO 4406:1999; the standard NAS 1638 (under revision) is also quite used. INTRODUCTION CONTAMINATION CLASSES ACCORDING TO ISO 4406:1999 The Contamination Class according to this standard is described by 3 numbers indicating the number of particles per 100 ml of fl uid having bigger size than 4, 6 e 14 ìm(c) respectively. ISO Code Number of particles per 100 ml more than up to 22 2.000.000 4.000.000 21 1.000.000 2.000.000 20 500.000 1.000.000 19 250.000 500.000 18 130.000 250.000 17 64.000 130.000 16 32.000 64.000 15 16.000 32.000 14 8.000 16.000 13 4.000 8.000 12 2.000 4.000 11 1.000 2.000 10 500 1.000 9 250 500 8 130 250 The above Contamination Class describes a fl uid containing: - between 1.000.000 and 2.000.000 particles 4 ìm(c) per 100 ml - between 130.000 and 250.000 particles 6 ìm(c) per 100 ml - between 16.000 and 32.000 particles 14 ìm(c) per 100 ml ISO Code 21/18/15: 21 4 ìm(c) 18 6 ìm(c) 15 14 ìm(c)