Lube-Tech
Fire Resistance SPE base oils are an alternative to unsaturated esters and PAGs in formulating anhydrous fire-resistant hydraulic fluids (HFD-U fluids) which are commonly used in the steel and aluminium processing industries. Unsaturated esters such as trimethylolpropane trioleate offer high fire points but are prone to oxidation in high temperature equipment. PAGs are oxidatively and hydrolytically more stable but require careful conversion practices when transitioning equipment from a petroleum oil to a PAG. The hybrid functionality of SPEs can provide the high performance of PAGs while being compatible with petroleum oils. Table 3 shows fire resistance performance data of two SPE base oils (ISO-46 saturated and 68 unsaturated).
PUBLISHED BY LUBE: THE EUROPEAN LUBRICANTS INDUSTRY MAGAZINE
No.144 page 5
hydraulic fluids (MIL-PRF-83282). SPE base oils are recommended for formulating industrial fire-resistant hydraulic fluids to meet Factory Mutual and ISO-12922 standards for fire resistant fluids.
Formulated Lubricants using SPEs The excellent laboratory performance of SPE base oils led to a program to evaluate them in formulated lubricants and in equipment trials. As an example, a formulated hydro-turbine oil was developed, and its properties illustrated in Table 4. In oxidation stability tests (RPVOT and dry-TOST), the fluid exhibited excellent performance. Demulsibility and foaming characteristics were good, and the product demonstrated compatibility in ferrous and copper corrosion testing. This data coupled with their excellent environmental performance provided confidence in moving the technology from the laboratory into equipment trials.
Table 3: Fire resistance performance of ISO-46 and 68 SPE Base Oils.
Base oil 68U exhibits a high fire point, high flash point and autoignition temperature. Both grades performed well on tests for spray flammability per the US Federal Standard 791D (6052) High Temperature- High Pressure Spray Ignition test. In this test the oil is heated to 100°F (37.8°C) and pressurised to 1000 psig. The pressurised oil is sprayed through a nozzle as an oxyacetylene flame is applied. No ignition was observed, and the fluids were rated as non-flammable. In tests for flame propagation rate and wick lighting, both base oils exceeded the requirements specified for standard hydraulic fluids (MIL-PRF-5606) and for fire resistant (FR) aviation
30 LUBE MAGAZINE NO.173 FEBRUARY 2023
Table 4: Formulated Hydro-turbine oil using SPE Technology.
The Global Center of Excellence for GE Hydro Solutions in Birr, Switzerland verified the performance of the formulated turbine oil on a combined thrust guide bearing test rig (Figure 5).
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