6.2), and the Kvartett (Einarsson, 1992) uses a large sodium iodide crystal. In specialized experiments involving lubrication in the presence of special gases, e.g. It is therefore very important to know the values of these parameters in order to conduct the accurate simulation experiments. The solubility and diffusivities of oxygen or other reactive gases influence scuffing, corrosive wear and other phenomena involving film formation by chemical reaction. Gwidon W. Stachowiak, ... Grazyna B. Stachowiak, in Tribology Series, 2004. This Roelands extrapolation is shown in Figure 4 as the dashed curve. The presence of reactive species such as oxygen, sulphur and halogen compounds in the lubricant needs to be determined as these can either induce corrosive wear or else provide some degree of ‘Extreme Pressure’ lubrication and obscure the results obtained. An active shield or guard detector consists of a volume of scintillating material (e.g., a plastic scintillator such as NE-110, a mineral oil-based scintillator, or even a large sodium iodide crystal) and either one or two additional PMTs. The main constituent of mineral oil is long-chain alkane. The limiting stress-pressure coefficient is λ = 0.0475. Where water is present in significant quantities, e.g. Figure 4 – Mineral vs. For oils with the same specific gravity, we would opt for the lower viscosity. It should then be possible to obtain the pressure-viscosity behavior to high pressure by correcting the Roelands viscosity, μR, from equation (5) by multiplication by a power series in p. We began our traction calculations by repeating the Eyring calculations of Muraki [4] for SR. Only at the highest pressure, PH = 1.06 GPa, were we able to reproduce the traction data using Roelands viscosity and the Eyring law. Equation (14) is plotted in Figure 4 as the dash-dot curve. We then used a least squares regression to fit the limiting stress equation (6) and the Roelands correction (13) to the measured traction. Muraki and Dong [4] measured the traction of a solvent refined paraffinic mineral oil and fitted the Eyring Law (8) and the Roelands equation (5) to these data. However, dynamic viscosity is becoming common in the area of used oil analysis because most onsite viscometers sold on the market today measure dynamic viscosity, not kinematic viscosity. Scott Bair, Ward O. Winer, in Tribology Series, 2000. While the high-pressure properties of mineral oils with the same atmospheric pressure viscosities may be quite different, the viscosity of SR shown in Figure 4 is within experimental error identical to the directly measured viscosity of the solvent refined paraffinic used by Muraki at 30 °C and pressures to 0.3 GPa. GORDON T COOK, ... BRIAN CARTER, in Handbook of Radioactivity Analysis (Second Edition), 2003. Lubricants comprise a very wide variety of fluids ranging from the conventional mineral oils to synthetic silicone-based fluids. Test environments range from ambient conditions to extremes of temperature, pressure and high levels of radiation. Kojola et al., 1984). fatty acids and alcohols present in the lubricant may cause adsorbed films to form on the worn surface which can either reduce friction or impede the functioning of solid lubricants. Note that the Roelands extrapolation is inconsistent with the directly measured pressureviscosity curves at higher temperatures. The quality of an engine oil depends on the base stock and its properties as well as on the additives. halons or chlorine gas, or nuclear radiation, the composition and pressure of the gas or the type and intensity of nuclear radiation should be determined. By continuing you agree to the use of cookies. Remember that at low temperature, direct measurement is prevented at high pressure by phase separation. Again, when realistic pressure-viscosity behavior is utilized it is found that the limiting stress is operating in the regime of traction usually attributed to Eyring behavior. Yasutomi and Roelands are in agreement to 0.6 GPa but diverge at high pressures. Figure 9.8 illustrates the infrared absorption spectrum of the mineral oil before and after the wear tests. Muraki found that extrapolated viscosities from traction curve fits were in agreement with the viscosity extrapolated from Roelands. The calculated traction using limiting stress is tabulated in the last column. Synthetic Oil – Molecule size. Recall that Muraki used a different exponential pressure-viscosity equation for each pressure. Lubricant and environment need to be well characterized in order to achieve valid experimental results. More importantly, the pressure viscosity coefficient, α, is quite different at high pressures with Roelands giving the lower value. This has the effect of reducing PMT crosstalk from Cerenkov light-induced pulses, which are primarily caused by the interaction of cosmic muons with the PMTs.