Importance Of Fire Resistant Hydraulic FluidHydraulic fluid is the medium for energy transfer in all hydraulic systems. This simple function is achieved only by a fluid that does not easily trap gases. The problem of trapped gas and foaming induces a high degree of compressibility in a fluid, usually dependent on supporting a very rigid, fast reaction system.
Conducting energy is the main function of hydraulic fluid; it is also useful in four secondary operations - heat transfer, contamination removal, damping, and lubrication.
Hydraulic machines produce too much heat in normal operation, often due to inefficiency within components. Pumps and motors allow the fluid to pass through the fine-grained clearance between the internal parts when the system pressure is high. In this situation, heating is caused by large amounts of Fire Resistant Hydraulic Fluid molecules against the metal surfaces. Without a method of moving thermal surfaces away from these surfaces, overheating can damage seals, valve plates, and other components.
As the oil returns to the reservoir where a large amount of fluid is placed, it passes through the cooler to help maintain an optimal temperature range before being pumped into the system.
The hydraulic liquid can also carry heat from a hot tank or a special warming circuit to a cold system to help reduce the possibility of damage when the cold starts.
Closed-loop hydraulic systems require a special circuit connected to the tank, to ensure that some oil is always cooling. A charge or refill pump brings cooling oil back into the circuit to maintain suitable overall system temperature.
Hydraulic fluid can suspend and can also carry solid particles and water from sensitive components. Filters and other conditioning devices perform the important function of removing and trapping contaminants, allowing the clean fluid to return circuit.
Knowing that contaminants are suspended in a fast-flowing stream of fluid is not an option for cylinder wear monitoring or an appropriate filtration program. When a valve opens only slightly, and the pressure difference across the valve is high, the same suspended particle can now cause transient damage to the valve, as it was the size of a file or grindstone.
Although the seal and the O-ring close the major clearance between parts, hydraulic oil finishes work in fine clearances where the solid material of an undershot shaft seal can damage.
Another example is the spool valve, which has a seal at each end to prevent oil from escaping the atmosphere. Each notch and undercut on the spool inside the valve is sealed next only with a tight tolerance of the spool, and the valve bore, together with resistance to oil surface tension and shear.
Critical to this function is the viscosity of the fluid. Viscosity index (VI), which is the change in viscosity at a swing of temperature change is also a major factor. A fluid with a high VI number can resist changes in viscosity as it heats up, allowing the fluid to maintain a consistent seal.
Most Fire Resistant Hydraulic Fluid components require lubrication to protect internal parts from friction wear. The oil provides full film lubrication between the moving parts, such as the slippers and valve plates of a piston pump. Without the lubricating properties of the oil, the hydraulic system would be Fire Resistant Hydraulic Fluids unreliable with a very short life for many components.
Knowing that contaminants are suspended in a fast-flowing stream of fluid is not an option for cylinder wear monitoring or an appropriate filtration program. When a flow of valve opens only slightly, and the pressure difference across the valve is high, the same suspended particle can now cause transient damage to the valve, as it was the size of a file or grindstone.
Most hydraulic machines use refined mineral oil base stock or synthetic oil. These oils are planned and fabricated to specific industrial test standards for critical properties such as viscosity, pour point, and viscosity index. These three properties, along with ambient and working temperatures, are often carefully considered when choosing a fluid.
If the ambient machine temperature is low, one will select an oil with low rated viscosity and insert point. The pour point is simply the temperature at which the oil will still pour. If a machine observes different temperatures according to an all-weather mobile machine, a high viscosity index is important.
It is imperative to consider the viscosity requirement specified by the component manufacturers. A piston pump, for example, requires a viscosity between 16 and 40 centistokes. Centistokes describe the viscosity (measured during flow) of a fluid, regardless of temperature. This data helps the user select the final ISO viscosity that will correspond to the required kinematic viscosity at the final operating temperature.
Hydraulic oil consists of a package of chemical mechanisms designed to improve the performance of both oil and components in a hydraulic system. These additives can improve oil foaming resistance or help quickly drop into the tank. Any trapped air is brought into the hydraulic system through a malfunctioning cylinder or motor seal or a poorly sealed hose connection. Corrosion and oxidation inhibitors are powerful chemicals that can eventually reduce the internal production of particulate contaminants in the form of water traps and keep it away
from ferrous metal surfaces.
Vane pumps are one of the most efficient from a larger standpoint. There is small if any clearance between the edge between the Vane and the cam ring. To help increase a lubricant for these pumps, a hydraulic fluid with an antiviral or excessive pressure additive is required. These additives react with metal surfaces, forming a thin, sacrificial lubricant film.
The composite additive package often separates high-quality fluids from the price of hydraulic oil by the economy, where a poor additive mixture can be corrosive to the yellow metals (brass and bronze) used Fire Resistant Hydraulic Fluids in hydraulic components.
Hydraulic fluid is the life-blood of many fixed machines. The care that must be Fire Resistant Hydraulic Fluids taken to maintain this precious medium is difficult to overdo. It is equally important to remember that while a quality fluid is designed to be engineered and perform challenging tasks, it cannot compensate for an understander reservoir or a system with excessive shaft load.
If the hydraulic components are properly specified, and the overall system is well designed, a good quality hydraulic fluid will perform the critical function that connects the pump and actuator and all components in between.
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