Hydraulic fluids fire resistance

Fire-Resistant Hydraulic Fluids. Fire-resistant hydrauhc fluids are used where the fluid could spray or drip from a break or leak onto a source of ignition, eg, a pot of molten metal or a gas flame (17). Conditions such as these exist in die-casting machines or in presses located near furnaces. Specific tests for fire resistance are conducted by Factory Mutual in the United States. 

Phosphorus oxychloride hydraulic fluid, aq. fire-resistant Polypropylene glycol hydraulic fluid, fire-resistant Tributyl phosphate Tris (isopropylphenyl) phosphate... 

Skydrol 500A hydraulic fluid, fire resistant, isooctyl diphenyl phosphate, Monsanto 23 30 6 Not stable 0.1 Trogamid T Huls America Specimen 4 mm (0.158 in) thick sample for weight change... 

Fluids for Hydraulic Transmissions-Fire Resistant Fluids—Classifications, Provisional Recommendation RP7.7H, European Oil HydrauHc and Pneumatic Committee, 1976. 

Typical application areas are industrial gear oils and greases, compressor lubricants, metalworking fluids, aqueous quenching fluids, fire-resistant hydraulic fluids, textile lubricants and heat transfer liquids. Section 2.7.5 gives a detailed account of these applications. 

Fire-Resistant Hydraulic Fluids. The four classifications of fire-resistant hydrauHc fluids are Hsted below (7). Three of the four groups are fire resistant because they contain a significant amount of water which provides cooling and blanketing of the combustible materials. 

Other Fire-Resistant Hydraulic Fluids. Phosphate and more recently polyol esters are marketed as fire-resistant compounds. They are formulated with additives to control wear, oxidation, corrosion, and misting. Seal compatibdity and solvency characteristics of these fluids may be quite different from those of mineral ods. 

U.S. Bureau of Mines, Fire Resistant Hydraulic Fluids, Schedule 30, Dec. 11, 1959 Eactory Mutual Research Approved Standard Eess Ha ardous... 

Liquid phosphate esters, eg, tricresyl phosphate [1330-78-5] are one of two types of fire-resistant hydraulic fluids (qv). Fire-resistant fluids account for less than 10% of the total fluids market. Phosphoms-based fluids generally are stable at high temperatures in addition to being fire resistant. Approximately 10,000 t of organophophoms compounds were used in hydraulic fluids in 1994. The manufacture of these materials consumed ca 4000 t of POCI3. 

For a number of years HF-A oiTin-water emulsions have been used as a fire-resistant hydraulic medium for pit props. Concern over maintenance costs and operational life has created interest in a better anti-wear type fluid. Micro-emulsions are known to give better wear protection... 

Table 52.7 CETOP classifications of fire-resistant hydraulic fluids...

Organophosphate esters are among the most widely used classes of synthetic compounds in hydraulic fluids. They are used as anti-wear additives in mineral oil hydraulic fluids and are significant components in certain fire-resistant hydraulic fluids (FMC 1991c, 1991d, 1992a, 1992b Wills 1980). 

The physical properties important for the projected use of hydraulic fluids are viscosity, density, foaming behavior, and fire resistance. There is no generally recognized test method for measuring flammability of hydraulic fluids, although various test methods maybe utilized (Moller 1989). 

In 1991, 12.5 million gallons of fire resistant fluids (probably including water-in-oil emulsions) were sold this is the lowest sales volume since 1985 (NPRA 1992). No detailed breakdown of water-in-oil emulsion hydraulic fluids was provided in NPRA (1992). 

Organophosphate Ester Hydraulic Fluids. Organophosphate ester hydraulic fluids are used in applications that require a degree of fire resistance such as in aircraft. EPA (1992b) has noted that aircraft mechanics may have dermal exposures of 1,300-3,900 mg/day and that 2,200 aircraft workers are routinely exposed to tributyl phosphate, while another 43,000 mechanics may be exposed at various times. Estimates of worker exposure in other industries were not found in the available literature. General population and military personnel exposure to organophosphate ester hydraulic fluids is likely to be much lower than exposure to mineral oil hydraulic fluids because these fluids have more specialized uses. 

Organophosphate Ester Hydraulic Fluids. Populations with potentially high exposures to organophosphate ester hydraulic fluids include aircraft mechanics and other mechanics repairing and maintaining hydraulic equipment designed to operate near combustion sources that require fire resistant hydraulic fluids. 

ASTM. 1966. Fire Resistance of Hydraulic Fluids. American Society for Testing and Materials, Philadelphia, PA. 

Healy CE, Nair RS, Ribelin WE, et al. 1992. Subchronic rat inhalation study with Skydrol 500B-4 fire resistant hydraulic fluid. Am Ind Hyg Assoc J 53 175-180. 

Monsanto. 1980. Evaluation of potential hazards by dermal contact. Test material SH-79-007, Skydrol (R) 500B-4 Fire resistant hydraulic fluids. 

Monsanto. 1988b. In vitro cytogenetics study of Skydrol LD4 fire resistant hydraulic fluid. Study No. 87066. Project No. 87-57. 

Monsanto. 1992a. Material safety data for Skydrol 500B-4 fire resistant hydraulic fluid. 9/15/92. Monsanto Company, 800 North Lindbergh Boulevard, St. Louis, MO. 

A molecular sieve bed was used to purify continuously the fire-resistant hydraulic fluid (a triaryl phosphate) in a large hydraulic press. Periodically the sieve bed was regenerated by treatment with steam, and then purified air at 205°C. After 9 years of uneventful operation, the bed ignited on admission of hot air. The fuel source was traced to the accumulation of organic residues (phenols or cresols ) on the sieve which were not removed by the steam/air treatment. 

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