The weather is gradually getting warmer and it is vital that you ensure that the fluid power equipment you design, operate or maintain is adequately equipped to cope with changing temperatures. Though winter weather is to blame for most adverse fluid power system failures, warmer weather has a few drawbacks. By preparing your plant and systems for the summer season, you can take steps to mitigate risks to your hydraulic and pneumatic equipment.
Because the viscosity of petroleum-based hydraulic oil decreases as temperature increases, take a look at your oil’s viscosity chart. Low oil viscosity causes loss of lubricating film strength. As a result, if the load remains constant but higher operating temperatures cause oil viscosity to fall below your requirements, boundary lubrication occurs with the possibility of increased friction, abrasion and adhesive wear.
One way to help your hydraulic machines cope with warmer temperatures is to ensure that you are able to control your oil’s operating temperature. This means that you must make sure that you have adequate cooling processes in place before warmer weather arrives — be sure to inspect all cooling devices before it’s too late.
Very few hydraulic systems have an overall efficiency greater than 85-90%, with lower-efficiency systems generating more heat. Therefore, any hydraulic systems with low efficiency (continuous heat generation) may require heat exchangers. If you are using heat exchangers with your systems, be sure that they are not undersized for the application, which can compound your heat problem when your machines encounter higher ambient temperatures.
In addition to contributing to the loss of full-film lubrication, high-temperature operation also reduces the life of your oil, seals and hoses. It’s better to have too much (rather than too little) installed cooling capacity because of this.
Depending on your location, higher temperatures can also mean higher humidity, resulting in increased ingression of water into your hydraulic systems. Potentially detrimental effects associated with water in hydraulic oil include surface corrosion and accelerated fatigue of metal components. Water may also change the physical characteristics of your oil, resulting in reduced viscosity.
Before the humid weather sets in, perform oil analyses on all systems to determine their water content. Then, replace hydraulic reservoir air breathers with desiccant breathers and periodically filter oil in the reservoir with a portable offline filtration unit (filter cart) using water removal elements.
With almost every application, clean, dry compressed air results in lower operating costs. When air is contaminated with dirt, water and oil, those contaminants are deposited on inner pipe and fitting surfaces, causing pressure to drop and a loss of performance efficiency. Water also accelerates corrosion and shortens useful life of equipment. The resulting corrosion particles can plug valves, fittings, instrument control lines, tools and other areas, causing larger problems.
In order to prevent these things from happening, you should be diligent about servicing and installing pneumatic filters, which trap water and particulates. You should also examine your method for draining water — manually or automatically by volume or timed release. Servicing or installing pneumatic air dryers can also help treat your compressed air.
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