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Friday, 4 January 2013

Choosing the correct hydraulic oil

By choosing the correct hydraulic oil you can realise substantial savings.

Choosing the correct hydraulic oil can be as simple as sticking to the manufactures’ specifications. But in this age of constant change, sticking to the book could be limiting both the efficiency and life of the equipment.

What Information Do You Need Before Choosing The Correct Hydraulic Oil.

For most machines, there are many options when it comes
to selecting hydraulic oil. Just because a machine will run with a particular product doesn’t mean that product is the best for the application.

Choosing the wrong hydraulic oil won’t usually lead to sudden and catastrophic failure; rather, a misspecification shortens the average life of the components and, thus, goes unnoticed.

With hydraulics, there are two primary considerations – the viscosity grade and the hydraulic oil type (AW or R&O). These specifications are typically determined by:
  • The type of hydraulic pump used in the system 
  • The operating temperature 
  • The system’s operating pressure. 
Selecting the best product for your system requires that you collect and utilize all available information.

Types Of Oil To Consider When Choosing The Right Hydraulic Fluid.

Choosing the correct hydraulic oil is vital when you consider the role it has to play in an efficient system: These roles range from a heat transfer medium, a power transfer medium and a lubrication medium. 

The chemical makeup can take many forms when selecting for specific applications. It can range from full synthetic (to handle drastic temperature and pressure swings) to water-based fluids (used in applications where there is a risk of fire).

Why Choose Synthetic Hydraulic Oils

A synthetic fluid is a manmade chain of molecules that are precisely arranged to provide excellent fluid stability, lubricity and other performance-enhancing characteristics. Definitely the right hydraulic oil to choose where high or low temperatures are present and/or high pressures are required. There are some disadvantages, including high cost, toxicity and potential incompatibility with certain seal materials.
When Would Choosing Mineral Based Hydraulic Fluids Be The Right Choice?
These are more common and are made from refining crude (to a desired level) to achieve better lubricant performance with the inclusion of additives, which range from anti-wear (AW), rust and oxidation inhibitors (RO) and viscosity index (VI) improvers.

These hydraulic fluids offer a lower-cost alternative to synthetics and can be very comparable in performance when certain additive packages are included.

For Which Applications Would You Choose Water Based Hydraulic Fluids

Water-based fluids are the least common of the fluid types. These fluids are typically needed where there is a high probability of fire. They are more expensive than petroleum but less expensive than synthetics. While they offer good protection for fire, they do lack on wear protection abilities.

Choosing The Correct Hydraulic Oil Based On Pumps And Their Viscosity Requirements 

There are three major design types of pumps used in hydraulic systems: vane, piston and gear (internal and external), and each of these pump designs are deployed for certain performance tasks and operations. Each pump type must be treated on a case-by-case basis for lubricant selection.

Vane: The design of a vane pump is exactly what its name depicts. Inside the pump, there are rotors with slots mounted to a shaft that is spinning eccentrically to a cam ring. As the rotors and vanes spin within the ring, the vanes become worn due to the internal contact between the two contacting surfaces. For this reason, these pumps are typically more expensive to maintain, but they are very good at maintaining steady flow. Vane pumps typically require a viscosity range of 14 to 160 centistokes (cSt) at operating temperatures.

Piston: Piston pumps are your typical middle-of-the-road hydraulic pump, and are more durable in design and operation than a vane pump; they can produce much higher operating pressures, up to 400 Bar. The typical viscosity range for piston pumps is 15 to 160 cSt at operating temperatures.

Gear: Gear pumps are typically the most inefficient of the three pump types, but are more agreeable with larger amounts of contamination. Gear pumps operate by pressurizing the fluid between the trapped air volume of the meshing teeth of a gear set and the inside wall of the gear housing, then expelling that fluid. There are two main types of gear pumps, internal and external.

Internal gear pumps offer a wide range of viscosity choices, the highest of which can be up to 2,200 cSt. This type offers good efficiency and quiet operation, and can produce pressures from 200 to 240 Bar External gear pumps are less efficient than there counterpart, but have some advantages. They offer ease of maintenance, steady flow, and are less expensive to buy and repair. As with the internal gear pump, this variety can produce pressures ranging from 200 to 240 Bar, but the viscosity range is limited to 300 cSt.

Application-Based Selection Of Hydraulic Oils.

Application-based selection techniques are the reality checks when choosing the correct hydraulic oil. Making sure the proper viscosity, additives, etc., tie in with the application’s requirements and operating conditions.

Merely following OEM specifications will not be enough when choosing the correct hydraulic oil; these are typically for best-case scenarios.

Don’t guess when choosing the correct hydraulic oil; Give Habot Synthetic Lubricants a call, and our professionals will help you choose one of our quality products that meets your applications requirements.