Read on to find some about facts about hydraulic oils.

The first fact about hydraulic oils is that they are not readily compressible: Have you ever driven through a deep puddle of water only to have your hapless engine lock solid after ingesting a cylinder full? This is known as hydraulic lock and is an expensive illustration of hydraulic power which hydraulic oils convey.

In this article I’ll be focusing on some interesting facts about hydraulic oils as opposed to brake fluids, which
are a very specialised sub category.

Facts about hydraulic oils and their functions and properties.

The primary function of hydraulic oils is to convey power. However, there are other facts about hydraulic oils and their important functions. Below are some facts about hydraulic oils and the major functions and properties of the fluid that affect its ability to perform that function:

• Low compressibility (high bulk modulus) 
• Fast air release • Low foaming tendency 
• Low volatility Thermal performance 
• Good thermal capacity and conductivity Sealing properies 
• Adequate viscosity and viscosity index 
• Shear stability Lubrication 
• Sufficient viscosity for film maintenance 
• Low temperature fluidity 
• Thermal and oxidative stability 
• Hydrolytic stability / water tolerance 
• Cleanliness and filterability 
• Demulsibility 

• Wear reduction characteristics 
• Corrosion control Pump efficiency 
• Proper viscosity to minimize internal leakage 
• High viscosity index Special requirements 
• Fire resistance
• modifiers 
• Radiation resistance Environmental impact properties 
• Low toxicity when new or decomposed 
• Biodegradability

Composition facts about hydraulic oils.

Interesting facts about hydraulic oils show that hydraulic fluids date back to ancient Egypt where the medium for hydraulic fluid was water. It was only in the 1920s that mineral oil began to be used. This was due to oils inherent lubrication properties and performance at temperatures above the boiling point of water. Today most hydraulic fluids are based on mineral oil base stocks and more recently synthetic alternatives.

Other little know facts about hydraulic oils is that modern hydraulic oils can contain a wide range of chemical compounds, including: mineral oils, butanol, esters (e.g. phthalates, like DEHP, and adipates), polyalkylene glycols (PAG), phosphate esters (e.g. tributylphosphate), silicones, alkylated aromatic hydrocarbons, polyalphaolefins (PAO) (e.g. polyisobutenes), corrosion inhibitors, etc.

For environmentally sensitive applications, such as farm tractors and marine dredging (where there is the risk of an oil spill from a ruptured oil line), biodegradable hydraulic oils based on rapeseed (Canola) vegetable oil can be used (often blended with customized synthetic esters). Typically these oils are available as ISO 32, ISO 46, and ISO 68 specification oils

Other base stocks are used for specialty applications, such as for fire resistance and extreme temperature applications. Some examples include: glycol, esters, organophosphate ester, polyalphaolefin, propylene glycol, and silicone oils (For Brake fluids).

Facts about hydraulic oils used in Aircraft hydraulic systems.

For those of you that are interested in facts about hydraulic oils relating to aircraft fluids, it’s interesting to note that as aircraft performance increased, so the force required to operate mechanical flight controls increased, and hydraulic systems were introduced to reduce pilot effort. Hydraulic power is also used to start the auxiliary power unit (APU) for self-starting the aircraft's main engines. While many aircraft equipped with the M61 family of cannon, use hydraulic power to drive the gun system, permitting reliable high rates of fire.

Below are some facts about hydraulic oils relating to the more common aircraft Phosphate-ester based hydraulic oils.

• Skydrol 500B-4 (Type IV class 2) 
• Skydrol LD-4 (Type IV class 1) 
• Skydrol 5 (Type V) 
• Skydrol PE-5 (Type V) 

As with other modern oils new synthetic hydraulic oils are blended to optimise the product for specific conditions – such as Skydrol.

If you’re interested in more interesting facts about hydraulic oils bookmark Habot Oil’s website to continue reading about our superior lubricants and fluids.