The oil trapped in the system will produce heat and overheated oil can damage the seals and other components in the system. Also, every hydraulic oil utilized will have a predefined temperature rating that it can withstand. If the temperature exceeds the specified value, oil properties will change resulting in poor performance. So, the hydraulic oil cooler is a component for protecting the system from overheating by cooling the oil transmitted through the circuit. This component will help to maintain the required oil temperature.
Excess heat is produced by the energy loss in the hydraulic system, external sources and surrounding environment. Other benefits of using an oil cooler are ensuring proper lubrication of mechanical components, improving the service life of components, increasing equipment productivity, reducing service and repair costs, etc… Poor lubrication, cavitation, oxidation, increased internal leakage, deterioration of rubber and elastomeric seals, formation of harmful varnish are issues caused by excess heat in the hydraulic system.
As mentioned earlier(types and benefits of oil cooler), we have different varieties of oil coolers available and it needs to be selected by considering certain applications and cooler features. Other factors for consideration are heat load, power source, noise, operating costs, space available, environmental conditions, and more. Without considering these factors, it is impossible to choose the fittest cooler.
Air-oil cooler and water-oil cooler are the important types of oil coolers available. The air-oil cooler equipped with an electric or hydraulic ventilator will cool down the oil by streaming air through it. The water-oil cooler utilizes water to cool the system.
The following are the parameters for oil cooler selection.
- Consider information about the application
- Desired oil temperature and amount of heat that needs to be removed
- Supplied water temperature and ambient air temperature
- Required flow rate and oil to water flow ratio
- Operating pressure of the hydraulic system
- Properties of hydraulic fluid used
- Ease of cleaning and maintenance
- Considerations for future expansions
- Mechanical factors like material of construction, impingement protection, and thermal stresses
- Environmental contaminants that can affect the system
Next, how does an oil cooler works? The important components of an oil cooler are an oil reservoir, cooling fan, radiator and mini hydraulic motor, relief valve, filter/radiator bypass valve, oil level sight glass, filter block indicator, suction elbow and pipe kit. The oil cooler will transfer the accumulated thermal energy into a secondary medium(air or water) by passing the hot fluid through a series of thin tubes exposed to a temperature cooling medium.