Do you remember the hydraulic system operating at 145 degrees Fahrenheit a few months ago, but you didn’t worry about it since you knew cooler weather was on the way? That very same system is probably functioning at 160 degrees right now, and it could have shut down due to the excessive temperature. Any industrial hydraulic system that operates at temperatures higher than 140 degrees is operating at unsafe temperatures. When the temperature increases over 140 degrees, the oil’s shelf life is reduced by one-half for every 15 degrees.
Sticking valve spools can be caused by systems running at high temperatures because these temperatures can cause sludge and varnish to form. When the temperature is high, pumps and hydraulic motors will bypass more oil than normal, resulting in the machine operating at a slower speed. When the oil temperature is too high, the pump drive motor will need to draw more current for the system to function properly, which might result in the loss of electrical energy. At increasing temperatures, O-rings become more rigid, which results in an increased number of system leaks.
If the oil temperature is above 140 degrees, then what kinds of checks and testing should you perform? Continue reading to discover.
Heat Tolerance of Hydraulic Pumps
To begin, heat production is an inherent part of the operation of every hydraulic system. About one-quarter of the electrical horsepower input will be utilised to counteract the heat lost throughout the system. Heat will be produced whenever the oil is ported back to the reservoir, even if no productive work is being done simultaneously.
Regarding pumps and valves, the tolerances are often measured in the ten-thousandths of an inch range. Because of these tolerances, a small quantity of oil can constantly bypass the internal components, which increases the fluid’s temperature. There will be several resistances that the oil will come up against as it travels through the lines. By reducing the amount of oil that may pass through them, flow controls, proportional valves, and servo valves, for instance, can regulate the oil’s flow rate. A “pressure drop” happens whenever oil passes through the valves in the system. Because of this, the pressure that is present at the valve’s input port will be greater than the pressure that is present at the outflow port. Oil produces and absorbs heat whenever it moves from a higher to lower pressure. This can happen at any moment.
The Efficiency with Heat Exchanger
When a system is being developed for the first time, the reservoir and heat exchanger sizes are determined so that they can effectively remove the heat that is produced. The reservoir is designed in such a way that it permits some of the heat to escape into the environment through the walls. If the heat exchangers are suitably designed, they should remove the remaining heat, allowing the system to run at a temperature of about 120 degrees Fahrenheit.
Types of Hydraulic Pumps to Consider
The pressure-compensating piston pump is by far the most popular kind of pump. The pistons and the barrel have tolerances of approximately.0004 inches between them. Because of these tolerances, there is a possibility that some of the oil at the pump output port might run back into the casing of the pump. After that, the oil travels via the case drain line to reroute back to the reservoir. Since this scenario drain flow does not contribute to any meaningful work, it is transformed into heat instead.
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