Hydraulic Oils (ISO VG 32, 46, 68, 100, etc.) (H3)
Hydraulic oils are categorized by their base oil (mineral, synthetic, or vegetable) and special types like fire-resistant or biodegradable. Key features across all types include being non-compressible, providing lubrication, and having properties like anti-wear, corrosion resistance, and a stable viscosity over a range of temperatures. The specific type and grade depend on the application, with grades like ISO VG 32, 46, and 68 indicating the oil's viscosity or thickness.
Types: (H4)
- Mineral-Based Oils: Derived from crude oil, these are the most common and affordable type. They are suitable for general use in construction, agriculture, and industrial equipment.
- Synthetic Oils: Engineered for superior performance, these oils offer better thermal stability, oxidation resistance, and durability, making them ideal for high-performance or sensitive applications and aircraft.
- Fire-Resistant Oils: Used in high-risk environments like mines and steel mills, these oils are designed to resist ignition.
- Biodegradable Oils: Eco-friendly options used in applications where environmental impact is a concern, such as forestry and marine environments.
- Food Grade Oils: Formulated to be safe for use in food-processing equipment.
- Aircraft Hydraulic Oils: Specifically designed to withstand the extreme temperature and pressure conditions found at high altitudes.
Key Features: (H4)
- Non-compressible: The fluid must not compress under pressure to efficiently transmit power.
- Viscosity: This is a measure of the fluid's thickness and resistance to flow. Oils are graded by viscosity, such as ISO VG grades, which indicate the oil's resistance to flow at a specific temperature. A viscosity index (VI) indicates how much the viscosity changes with temperature.
- Thermal Stability: The oil must maintain its viscosity and lubricating properties across a wide range of operating temperatures (both hot and cold).
- Anti-wear: Additives in the oil provide a protective layer on moving parts to prevent wear and tear.
- Corrosion and Rust Protection: They protect metal components from rust and corrosion, especially in the presence of water.
- Oxidation Resistance: The oil should resist breaking down due to exposure to air, which can lead to sludge and varnish formation.
- Water Tolerance: They must be resistant to contamination from water, which can degrade performance and cause corrosion.