Miscellaneous Mechanical ComponentsDOE-HDBK-1018/2-93HYDRAULICSWhen using oil as a fluid in a high pressure hydraulic system, the possibility of fire or anexplosion exists. A severe fire hazard is generated when a break in the high pressure pipingoccurs and the oil is vaporized into the atmosphere. Extra precautions against fire should bepracticed in these areas. If oil is pressurized by compressed air, an explosive hazard exists if the high pressure air comesinto contact with the oil, because it may create a diesel effect and subsequent explosion. Acarefully followed preventive maintenance plan is the best precaution against explosion.SummaryThe important information in this chapter is summarized below.Hydraulics SummaryThe relationship between pressure and force in a hydraulic pistonis expressed mathematically as:F =P x A where:F =forceP =pressureA =areaOil from a tank or reservoir flows through a pipe into a pump. Thepump can be driven by a motor, turbine, or an engine. The pumpincreases the pressure of the oil.The high pressure oil flows in the piping through a control valve. Thecontrol valve changes the direction of the oil flow. A relief valve, set ata desired safe operating pressure, protects the system from an over-pressure condition. Oil entering the cylinder applies pressure to thepiston, developing a force on the piston rod. The force on the piston rod enables the movement of a load or device. The oil from the other side of the piston returns to a reservoir or tankvia a filter, which removes foreign particles.Rev. 0ME-05Page 13
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