Water hydraulic systems a commercial proposition

Reduction of leakage is a major problem in water hydraulic systems. With a servo valve, it is possible to reduce the internal leakage by reducing the clearance between a spool and a sleeve. However, because the clearance is reduced, wear tends to occur easily between the spool and sleeves when the servo valve is driven. As a result, the durability of the servo valve is reduced. Attention is paid to the durability against wear of ceramic materials, and the wear can be suppressed by using ceramics as the materials of the spool and sleeve. Thus, one can check whether the wear between the spool and sleeve can be suppressed, thereby improving the durability of the servo valve.

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EXPERIENCES ON THE LOW PRESSURE WATER HYDRAULIC SYSTEMS

Proceedings of the JFPS International Symposium on Fluid Power ◽

10.5739/isfp.1999.357 ◽

1999 ◽

Vol 1999 (4) ◽

pp. 357-363 ◽

Cited By ~ 2

Author(s):

Jussi AALTONEN ◽

Kari KOSKINEN ◽

Matti VILENIUS ◽

Pekka KUNTTU

Keyword(s):

Low Pressure ◽

Hydraulic Systems ◽

Pressure Water ◽

Water Hydraulic

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New Materials and Component Design - Key Factors for Water Hydraulic Systems

10.4271/2002-01-1381 ◽

2002 ◽

Author(s):

Karl-Erik Rydberg

Keyword(s):

Hydraulic Systems ◽

New Materials ◽

Key Factors ◽

Component Design ◽

Water Hydraulic

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Microbial water quality and diversity in hydraulic systems using tap water as a pressure medium

Water Science & Technology ◽

10.2166/wst.2000.0275 ◽

2000 ◽

Vol 41 (12) ◽

pp. 215-222 ◽

Cited By ~ 2

Author(s):

S. M. Soini ◽

K. T. Koskinen ◽

M. Vilenius ◽

J. A. Puhakka

Keyword(s):

Hydraulic System ◽

Tap Water ◽

Pilot Scale ◽

Hydraulic Systems ◽

Water Hydraulics ◽

Pressure Medium ◽

Viable Bacteria ◽

Water Hydraulic ◽

Cell Densities

Water hydraulics uses tap water or demineralised water as a pressure medium and has fewer environmental impacts than oil-using hydraulics. The applicability is restricted by the microbial quality of the medium. The objectives of this study were to determine whether microbes grow in the pressure medium of a water hydraulic system, biofilm is formed on the surfaces and to describe the diversity of bacteria that survive and grow in water hydraulic systems. A pilot-scale water hydraulic system was used in the experiments. The viable counts in the pressure medium increased in three days from 102 to 3 ×104 cfu/ml followed by a gradual decrease towards the steady-state concentration of 6× 1034 cfu/ml. The total cell numbers decreased from 3×105 to 2 ×104 cells/ml during the three weeks of operation indicating attachment onto the system surfaces as biofilms. The biofilm cell densities on collector slide surfaces varied between 7 ×103 and 1.2 ×104 cells/cm2 after 21 days of operation. The phosphatase activity in the pressure medium was in conformity with the numbers of viable bacteria. The enzymatic activities (α- and β- glucosidase, phosphatase, aminopeptidase) varied between 0.4 and 300 nmol/lh. The diversity of bacteria growing in the system was wide and differed from that of tap water.

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Semicrystalline polymer utilised on water hydraulic systems

World Pumps ◽

10.1016/s0262-1762(03)90052-6 ◽

2003 ◽

Vol 2003 (440) ◽

pp. 12

Keyword(s):

Semicrystalline Polymer ◽

Hydraulic Systems ◽

Water Hydraulic

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The Role of Dissolved and Nascent Air in Oil-Hydraulic Systems

10.1115/imece2000-1979 ◽

2000 ◽

Author(s):

Hansjoerg Stern

Keyword(s):

Steady State ◽

High Performance ◽

Transient Behavior ◽

Operating Conditions ◽

Phase System ◽

Hydraulic Systems ◽

Three Phase ◽

Significant Damage ◽

Water Hydraulic

Abstract In modern, high performance hydraulic systems the transient behavior of dissolving, dissolved and nascent air under changing dynamic conditions of pressure and temperature is emerging as an increasingly important factor, capable of creating undesirable operating conditions. The paper discusses the question of how to predict the performance of pump inlets and valve discharges, where we have known for some time that cavitation and cavitation-like conditions exist and can cause significant damage. The steady state conditions at which nascent air evolves from saturated air-in-oil solutions is normally one or two orders of magnitude above the vapor pressure of the system fluid. To what extent, therefore, is “cavitation” in these systems an air-oil problem? Or is it an oil-vapor problem that is analogous to cavitation in water hydraulic pumps and turbines? Or have we created the combination of the two, a three-phase system of liquid, gas and vapor?

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