Hydraulic fluids fluid sampling

After the type of system has been selected, many of these same factors must be considered in selecting the fluid for the system. This chapter is devoted to hydraulic fluids. Included in it are sections on the properties and characteristics desired of hydraulic fluids types of hydraulic fluids hazards and safety precautions for working with, handling, and disposing of hydraulic liquids types and control of contamination and sampling. 

All samples should be taken from circulating systems, or immediately upon shutdown, while the hydraulic fluid is within 5°C(9°F) of normal system operating temperature. Systems not up to temperature may provide non-representative samples of system dirt and water content, and such samples should either be avoided or so indicated on the analysis report. The first oil coming from the sampling point should be discarded, since it can be very dirty and does not represent the system. As a mle, a volume of oil equivalent to one to two times the volume of oil contained in the sampling line and valve should be drained before the sample is taken. 

Analytical Methods for Determining Mineral Oil and Polyalphaolefin Hydraulic Fluids in Biological Samples... 

No data were located regarding absorption in animals after inhalation exposure to organophosphate ester hydraulic fluids or specific organophosphate esters, except for the observation that parent material was not detected by gas chromatography in the blood or urine of male rats exposed to 5,120 mg/m3 of an aerosol of a cyclotriphosphazene (99.9%) hydraulic fluid for 4 hours, thereby suggesting that the extent of absorption was limited (Kinkead and Bashe 1987). Blood samples were collected at 0, 24, and 48 hours after exposure was terminated. Urine was collected for 24 hours after exposure. 

Organophosphate Ester Hydraulic Fluid. Analyses of blood or urine for the presence of organophosphates or their metabolites can be valuable in confirming exposure to organophosphate ester hydraulic fluids however, sample collections must be completed during or shortly after exposure unless exposure levels are very high. Urinary excretion of metabolites can be completed within a few days of exposure, depending on the level of exposure. 

Polyalphaolefin Hydraulic Fluids. None of the known components of polyalphaolefin hydraulic fluids are on the TRI. Releases of polyalphaolefin hydraulic fluids in air are probably similar to mineral oil hydraulic fluids. It may be difficult to estimate the release of polyalphaolefin hydraulic fluids to air by identifying occurrences of polyalphaolefin hydrocarbon isomers in air at a particular facility since these constituents also are present in mineral oil and concentrations of the components cannot always be uniquely associated with polyalphaolefin hydraulic fluid release. Nonetheless, the gas chromatographic profile of a polyalphaolefin will be very different than that of a mineral oil, and identification may be possible when polyalphaolefins predominate in a sample. 

The purpose of this chapter is to describe the analytical methods that are available for detecting, and/or measuring, and/or monitoring hydraulic fluids, their metabolites, and other biomarkers of exposure and effect to hydraulic fluids. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used for environmental samples are the methods approved by federal agencies and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). 

Polyalphaolefin Hydraulic Fluids. The methods for analyzing polyalphaolefin hydraulic fluids are identical to those for the mineral oil hydraulic fluids (see Table 6-1). Polyalphaolefin oils can be distinguished from mineral oils because they will be present in combinations of the alphaolefin from which they were synthesized (Shubkin 1993). Thus, polyalphaolefins obtained from 1-decene will be present as dimers (C20 alkanes), trimers (C30 alkanes), tetramers (C40 alkanes), pentamers (C50 alkanes), etc., with no alkanes between these isomers (e.g., there will be no C2i alkanes present in the oil). This method of identification will only be possible if the polyalphaolefin hydraulic fluids contain no mineral oils or if the samples being analyzed were not exposed to mineral oils. 

Mineral Oil Hydraulic Fluids. Methods are available for analysis of the hydrocarbon components of mineral oil hydraulic fluids (predominantly straight and branched chain alkanes) in environmental samples. Some of these methods are summarized in Table 6-3. In general, water and sediment samples are extracted with a suitable solvent in a Soxhlet extractor (for solid samples) or in separatory funnel or shake flask (for liquid samples) (Bates et al. 1984 Peterman et al. 1980). The extract is cleaned up on silica gel or Florisil columns using a nonpolar solvent to elute the nonpolar alkanes. Analysis is usually performed by GC/MS (Bates et al. 1984 Kawamura and Kaplan 1983 Peterman et al. 1980). Method performance has not been reported, although 82% recovery of aliphatic hydrocarbons was reported for rainwater (Kawamura and Kaplan 1983). 

Organophosphate Ester Hydraulic Fluids. Few analytical methods are available for analysis of organophosphate esters in environmental samples. A summary of methods is shown in Table 6-4. Care must be taken in the laboratory to assure that all labware, solvents and reagents are free of interfering contaminants. Organophosphate esters have widespread use and have been reported as sources of contamination (Muir 1984 LeBel and Williams 1986). 

The direction and flow rate of the test and hydraulic fluids are determined by nine three-way valves and six a1r-dr1ven hydraulic pumps that must be sequenced 1n the proper order. The position of the valves 1s determined by six air-driven actuators. Two of the pumps are miniaturized, air-driven, hydraulic pumps used for sample loading and pressurization. One of the remaining four pumps 1s a high-pressure, constant volume, positive displacement, piston metering pump to provide hydraulic pressure, and the other three are positive displacement syringe pumps for In-line addition of additives. 

Fig. 2 A schematic diagram of the VX3 model of the Paris-Edinburgh (P-E) press. Key (1) Hardened steel main frame (2) Breech (3) Piston (4) Hydraulic fluid inlet (5) Tungsten carbide toroidal-profile anvils with 2° bevel angle (6) Sample chamber. Note the scale...

Murray [91] has described a gas chromatographic method for the determination in water of triarylphosphate esters (lmol S-140, tricresyl phosphate, cresol phosphate). These substances are used commercially as lubricant oil and plastic additives, hydraulic fluids and plasticisers. The method involves extraction from the samples, hydrolysis and measurement of the individual phenols by gas chromatography as the trimethylsilyl derivatives. The lower detection limit was about 3ppm. 

VEGETABLE OILS AS LUBRICANTS, HYDRAULIC FLUIDS, AND INKS Sample analysis in micro oxidation... 

RECOVERIES (ppm) OF ORGANOPHOSPHORUS HYDRAULIC FLUIDS (OPS) FROM NATIVE SOIL SAMPLES (RSD. n = 3)... 

The solution obtained from dissolving an oil in a solvent is the simplest sample technique and involves dissolving a known weight of oil or fluid in a suitable solvent that is compatible, stable and noise free, and can be used for nebulisation with an ICP-OES plasma torch. Crude, lubricating oils and hydraulic fluids are soluble in a few solvents that are compatible with ICP-AES, e.g. kerosene, propylene carbonate, tetralin and decalin. The excitation of elements in solutions can be viewed either with radial or axial torches with the latter giving higher intensity readings and lower limits of detection. 

The Brool eld viscosity test measures the low-temperature viscosity of gear oils and hydraulic fluids under low shear conditions. Brookfield viscosities are measured in centipoise units using a motor-driven spindle immersed in the cooled oil sample, ASTM D2983. 

Fig. 3.17 The Paris-Edinburgh V4 press it has a nominal working capacity of 250 tonnes (2.5 MN) (1) sample and gasket arrangement (see Fig. 3.16), (2,3) anvil and seat binding rings, (4) breech, (5) upper platen, (6) B4C neutron collimator, (7) piston, (8) hole for transmission measurements, (9) O-rings, and (10) hydraulic-fluid inlet. The dimensions are in millimetres.

Fig. 7.4 A piston-cylinder high-pressure apparatus (a) the pressure frame, (b) a 100 tonne hydraulic ram, (c) the piston, (d) the bottom plug, (e) high-pressure seals, (f) a double-walled pressure vessel, (g) the pressurizing fluid, (g) a 500 bar hydraulic fluid for pressurization, (i) hydraulic pressure used for piston extraction, (j) the sample. (Reproduced by permission from PSIKA Ltd).

Fig. 7.6 An intensifier vessel (a) a double-walled pressure vessel (b) the top plug (c) the bottom plug, which admits the high-pressure fluid (d) duplex tubing (e) the high-pressure fluid (f) the low-pressure fluid (ca. 500 bar) (g) the hydraulic fluid (h) the sample (i) the pressurizing fluid.

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