Some experimental data have been obtained relating the load-bearing capacity of air films of various thicknesses and operating at different pressures and rates of flow for 2, 4, and 6-in. spherical-type bearings. Semi-empirical equations have been developed for calculation of (a) minimum air pressure as a function of load; (b) minimum flow of air as a function of pressure; (c) bearing lift as a function of air pressure.

A serious threat to life and property in many industries is the hazard of a pressurized hydraulic line rupturing, causing the escaping fluid to enter the flame of a fuel burner. The test described here simulates this danger and evaluates the fire resistance of hydraulic fluids under such conditions. The most important factor in the test equipment is the provision of a broad range of spray velocities and densities. The spray equipment is described and illustrated, and the test procedure is outlined. Data are presented from tests of one mineral oil, three water-in-oil emulsions, six water-glycol fluids, and nineteen synthetic organic fluids. Selected 35-mm colored slides illustrating the equipment and test conditions were made into black-and-white enlargements for this paper. In this process, much of the contrast was unfortunately lost. Only four synthetic organic fluids failed to ignite under one or more test conditions. All three water-in-oil emulsions tested ignited. However, when the fluid stream is of sufficient density and velocity, a typical mineral-oil hydraulic fluid will not ignite.

Hydraulic lines are known to rupture permitting a stream or spray of hydraulic fluid to encounter the flame of burning fuels or the surface of hot or molten metal. This is a prevalent cause of fires in many industries. High-pressure spray-flammability tests simulate this type of industrial hazard and are able to distinguish the difference in fire resistance among the various kinds of hydraulic fluids. The available high-pressure spray tests are inconvenient to use, however, since they usually must be done outdoors where they are subject to the vagaries of the weather. If done indoors, the tests must be performed in specially assembled fireproof areas. In addition, relatively large volumes of test fluids are needed, and the high-pressure pump, motor, and auxiliary equipment can become costly. A low-pressure spray-flammability test that can be conducted safely in a conventional laboratory hood is described. The equipment required is simple and inexpensive and only limited amounts of fluid and fuel are needed. The flame from a laboratory gasair burner serves as the source of ignition. The data obtained correlate very well with those from a conventional high-pressure spray-flammability apparatus. Results from both kinds of tests evaluating the several types of fire-resistant hydraulic fluids are presented in tabular and pictorial forms. A variety of test conditions is not available with the new method described, but the conditions are chosen so that they simulate practical industrial situations and provide correlation with other flammability tests at a sufficient confidence level.