Recommendations for the Use of Hydraulic Oils

construction crane

Statistics show that up to 70% of all damage caused by pollution of the hydraulic system or debris inside the system. Any professional engineer knows that the purity of the hydraulic oil - is the key to long-term operation of hydraulic machines. But cleanliness - it's not all. It is equally important to choose the correct hydraulic fluid and replace properly. This is what we will talk today.

General recommendations

In order to select hydraulic fluid two options should be considered. First - ambient temperature during operation. Second - the viscosity of the fluid in the working temperature range. The second parameter is specified in the instruction manual of each individual machine. Some sources state that the viscosity of the hydraulic fluid depends on the type of pump that is used in the system. This is not entirely true. The viscosity at operating temperature is calculated based on the bandwidth of the narrowest channel in the hydraulic system, as the hydraulic fluid must have a certain rate of flow through these channels, otherwise hydraulics will not work correctly. Thus, for many construction machines, using the same models of hydraulic pumps different types and brands of hydraulic fluid are often used. For example, in modern hydraulic excavators, so-called "proportional" valves with very small cross section of the channel are used. The system is quite complex, with electronic control components. If you choose the wrong viscosity of hydraulic oil for the system, the machine will not operate at full capacity. Accuracy or operations speed may reduce the. The recommended oil type is usually indicated in the cockpit on the special information labels or directly to the tank of the hydraulic system near the filler neck. Today the modern machinery often recommends using high viscosity grade oil HVLP. This is hydraulic oil with a more modern package of additives than in oils class HLP. Oils of this class have more stable viscosity-temperature performance, and in severe cold conditions they work better. Manufacturers of these oils indicate the temperature range from - 30 to + 60 degrees Celsius. In addition to stable temperature characteristics of oils of this class possess multifunctional additives to improve anti-oxidation, anti-corrosion, anti-wear, depression, water separation, anti-foam properties of the liquid.

VMGZ against HVLP

For a long period of time Russian machines used two brands of hydraulic oil: VMGZ and MGE-46. In principle, these oils are not bad performance, but only for that equipment, which is operated in a relatively easy mode: loaders, backhoe loaders, dump trucks, cranes lungs. If there is such a need, it is not forbidden to use this oil in modern machinery, which does not work in very hard conditions. However, it is not recommended to use these oils in modern hydraulics, which is controlled by servos. If we are talking about hydraulics, which are subject to very strict requirements in terms of reliability and performance, the experts advise to pay attention to imported hydraulic oil. However, not so long ago on the Russian market appeared domestic products whose characteristics are not inferior to modern foreign analogues. For example, several years ago, TNK has issued a series of hydraulic oils. The new lineup of products, along with oils and MGE counterparts multigrade oil VMGZ already presented lubricants class HLP and HVLP. On the quality of this class of Russian oil experts still expressed caution. Not much praise, but do not make serious claims. The basis for the oil continues to serve the domestic raw materials. Strangely enough service life of these oils in 2-3 times lower than similar imported.

But the use of industrial hydraulic oil I-20, I-30, etc. which is used in such a massively industry, is strictly forbidden. These oils have very high hygroscopic, ie in contact with air, they are beginning to absorb water molecules. This leads to disastrous consequences for the hydraulic system from corrosion and ending with hydraulic shocks in the system. In addition, there is practically no industrial oil additive package necessary to protect the inner surfaces of the hydraulic system from premature aging.

With regard to preferences in choosing a particular brand of hydraulic oil, in this issue can rely, as they say, to your taste. The fact that no significant differences in the composition of a class of oils from different manufacturers is not noticed. Basic kits additives all companies are the same. Producers of base oil in the world is not so much. The difference in structure, of course. Each manufacturer strives to ensure, to highlight some of the important characteristics of its oil. One relies on the temperature properties, the other - the increased protection against corrosion, and the third - an increased service life and so on. It has nuances. O hydraulic oils produced in USA, which are placed on the market without indication of the brand, such can be said. So even if you make a choice in favor of oils class VMGZ or MGE, it is better to buy products of the leading USA producers. The choice in favor of a brand is often due to the cost of the technology itself. The difference in price between one class of oils from different manufacturers can be up to 20%. As a rule, owners of expensive new cars prefer not to save on oil, especially during the warranty period, they are forced to accept those oils that are being offered at the dealership service center. Buyers and owners of second-hand imported cars favored lubricants market leaders and foreign manufacturers an average price segment.

The most important rule when choosing a used oils - is, first of all: The manufacturers instructions techniques, which focus primarily on generally accepted international standards (SAE, ISO.); and secondly, of all the products that meet the stated requirements, give preference to the most authoritative brand and reliable supplier. Otherwise, a malfunction of hydraulic systems. Currently «Select Lubricants» manufacturer of hydraulic oil series SL-Hydraulic, applicable in all cases, when you need a high-quality reliable hydraulic oil with high viscosity index and ability to work in a wide range of temperatures and pressures in the most adverse climatic conditions.

In winter and summer ...

Hydraulic oil should not be used year round. Especially when it comes to second-hand machinery. In pumps with a high degree of wear of the gaps between the friction parts are bigger. If the winter oil is used and a viscosity at strong heating becomes very low, the pump performance will decrease dramatically. The oil pumped will simply spill out between the plunger and the pump casing. This reduces not only the pump efficiency, but also the pressure in the system. Using winter fluid in summer may lead to lubrication failure of the pump due to its low pumpability. This is especially true in the equipment, which is equipped with powerful hydraulic pumps (cranes, concrete pumps, excavators, etc.). Some "artisans" to reduce the viscosity of the frozen oil pour into the hydraulic system a certain amount of diesel fuel. This leads to a very disastrous consequences. The fact that when the hydraulic system, despite the presence of antifoaming oil additive in the hydraulic fluid air bubbles are formed. With heavy use oil boils. If oil is present in the fuel, the inside of bubbles are almost ready fuel-air mixture. When compressed oil in the hydraulic cylinders occurs absolutely the same process as that in the diesel engine: in vials mixture under pressure ignites and rapidly destroys hydraulic cylinders. Skilled, repair hydraulics, at dismantling the cylinders quite often come across melted seal - this is the result of the addition of "diesel fuel" in the oil.

The rules of the Workers 'hygiene'

Instructions for replacing the hydraulic fluid are provided by almost all machinery manufacturers. Unfortunately, not everyone reads and comply with them. Let me remind you the basic rules. The oil must be stored in clean closed canister. Before pouring fresh oil from the hydraulic tank, remove all the dirt that has settled in it for the last few months of operation. Oil should should be poured in clean containers only. Hydraulic systems have to refuel oil pump, not fill. In this case, the likelihood of dirt from the surface of the container into the system is greatly reduced. Filling the hydraulic system should be through the filter, since the purity of the liquid even in the original container does not always meet the requirements of hydraulic equipment. The oil which is contacted with air, can not be stored for more than two years. If it turned out that it had to be drained from the hydraulic system, which has not had time to work out its term (this often happens at various breakdowns hydraulics), then before you pour it back it does not hurt to analyze its characteristics. It is not too expensive. When it comes to heavy equipment with large gas volumes, this procedure is justified.

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