Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/985736
26 | May - June 2018 | www . machinerylubrication.com 5. Check the Heat Exchanger's Inlet and Outlet Oil Temperatures Check the inlet (F) and outlet (G) oil temperatures of the heat exchanger (HE). ere should be a noticeable temperature difference between the two lines. As oil flows through the tubes of an air cooler, the heat in the oil is transferred to the air. Depending on the size of the cooler, a temperature difference of 5-10 degrees can be expected. In Figure 6, the inlet oil tempera- ture is shown as being 117 degrees F, while the outlet temperature is 109 degrees F, which is acceptable. If the temperature difference decreases, this may mean that the cooler fins and core are dirty or the inner tubes have become contaminated. Use caution when cleaning the fins with an air hose so no bending of the fins occurs. On water-cooled units, the temperature difference usually will be much greater, especially if chilled water is employed. e inlet and outlet water temperatures should also be recorded for future trouble- shooting purposes. 6. Check the Tank Line Temperature of the Accumulator Dump Valve Check the tank line temperature (H) of the automatic accumulator dump va lve (EDV ). W hen t he system is operating, the solenoid is energized, which shifts the valve to the closed position. Flow from the main line will be blocked through the valve and back to the tank in this condition. e temperature of the line should be at or near ambient temperature. Notice in Figure 7 that the valve's tank line is 145 degrees F, indicating that the valve is either stuck open or that the solenoid has failed. 7. Check the Temperature of the Filter's Base and Element Housing Often an oil filter (RF) will have an internal bypass check valve, as shown on the schematic in Figure 1. e purpose of this check valve is to provide a flow path for the oil to return to the reservoir in the event the element becomes contam- inated. is prevents damage to the filter element. e temperature of the filter base should be compared to the temperature of the element housing. When the element becomes plugged, the housing will be cooler than the base. While many oil filters have visual dirt alarms to indicate the element condition, they should not be relied upon, as they have a tendency to fail over time. 8. Check the Tank Line Temperature of the Manual Valve Check the tank line temperature (J) of the manual valve (MDV). is valve is used as a manual accumu- lator dump valve. It should be opened anytime the system is shut down. is is to ensure that the pressurized f luid in the accumulator (ACC) bleeds down to 0 PSI. is provides a safety backup in the event the EDV valve were to fail closed when the system is turned off. e tank line of Figure 6. Images showing the inlet (left) and outlet (right) oil temperatures Figure 7. Image showing the tank line temperature of an automatic accumulator dump valve Figure 8. Image showing the tank line temperature of a manual valve HYDRAULICS