Fire Resistant Fluid
Whenever fire is present around hydraulic equipment, it cannot be over stated that operators and personnel working in the vicinity are always in danger from potential fire disasters. Working fluid compressed within the equipment can possibly burst out through fractures, cracks, and pinholes. It is almost impossible to stop leakage from the equipment, if it includes exudation and dribbling. The danger of fire disaster can thus never be neglected.
Detailed records of fire accidents have not been kept since hydraulic equipment has become widely utilized. But, actual accidents have occurred quite frequently. The large number of specifications made to assess the flammability of fluids testifies to this fact.
Working fluids chosen for their fire resistance capability are grouped and shown in Fig. 14.8. Many specifications have been created to assess flammability from multiple points of view. One specification compares the flammability of petroleum and hydraulic working fluid, and another compares the relative flammability of two different fire-resistant working fluids. Proper selection should be made based upon applications and conditions, etc.
Possible reasons for fire disaster are presented below. The specifications of combustion tests give due consideration to these causes.
(1) Working fluid is misted out, and ignited.
(2) Working fluid is directly poured into a source of fire.
(3) Working fluid exuded from equipment, or left on rugs or materials, is ignited.
Flammability test methods are categorized into the following two major groups.
(1) The test gradually increases temperature to the point of ignition, or increases the chance of ignition in a test object. From this, a quantitative scale can be extrapolated. Flash point tests, spontaneous combustion tests, and pipe cleaner tests are representative of this type of test.
(2) The test is a qualitative method that requires that the conditions necessary for ignition take place. Fluid is left in those conditions and observed to see whether ignition takes place or not. High pressure gas exhaust tests and manifold ignition tests are representative of this type of test.
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