Introduction to knowledge related to vacuum pump oil

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This post was last edited by qinweijun on 2012-2-16 at 16:42. Overview: Vacuum pump oil is a special type of lubricant designed specifically for vacuum pumps used in vacuum equipment; it comes in two forms: mineral oil and synthetic oil. Performance features: The vacuum pump oil possesses excellent oxidation stability; it does not deteriorate easily even when in prolonged contact with air, resins, chemical substances, and other materials at high temperatures. This reduces the formation of harmful coatings and oil residues, allowing for a longer oil change interval. 　　 The vacuum pump oil possesses excellent rust and corrosion resistance; it forms a highly effective protective film on metal surfaces, thereby preventing system corrosion caused by the absorption of corrosive gases and moisture. 　　 The vacuum pump oil can quickly separate the water contained in the oil, thereby achieving the desired level of vacuum. 　　 L Vacuum pump oils have a low vapor pressure, which prevents the oil from flowing back from the interior of the pump into the vacuum system and causing oil return. Thereby ensuring sufficient ultimate vacuum. Scope of application Vacuum pump oil is suitable for use in reciprocating booster pumps, mechanical booster pumps, and oil-sealed mechanical vacuum pumps, as well as in various diffusion vacuum pumps. Recommended for use in vacuum pumps in fields such as handicrafts, ceramics, and chemistry. Physical and chemical properties of the vacuum pump oil: 1. Kinematic viscosity – Based on the ISO standard, with a central value of 40 cmm2/s, there are seven different grades of products: VG46, VG68, VG100, VG22, VG32, VG50, and VG220. Various pump oil grades are determined based on the type of pump, speed, pumping rate, clearance, as well as limits regarding total pressure and partial pressure. 2. Viscosity index: Generally, it is believed based on experience that the higher the viscosity, the better the vacuum level. In fact, that’s not the case; “thin” and “thick” are merely relative terms based on visual inspection and tactile feel, with no quantitative data available. If the viscosity values of two oils are found to be the same at 40°C, then when those oils are cooled to room temperature, the \"thinner\" oil is better than the \"thicker\" one. Because the viscosity index of “thin” oil is higher than that of “thick” oil. The viscosity of sticky oils changes significantly with temperature; in other words, their viscosity index is low. The viscosity index is an important parameter for vacuum pump oils. Pump oils with a high viscosity index exhibit less variation in viscosity as temperature changes. Moreover, the cold pump operates easily, offering significant savings in energy consumption; especially in summer, as the ambient temperature and the oil temperature inside the pump rise, this oil’s critical pressure maintains its effective performance. 　　 3. Flash point The flash point is also one of the most important quality indicators for vacuum pump oil. It is considered not only in terms of flammability and safety. Rather, a high flash point usually indicates a lower content of light components in the oil. Therefore, as the oil temperature rises, light-boiling-point oil molecules are less likely to evaporate, allowing the critical pressure to be maintained effectively. 　　 4. Anti-emulsification capacity: During operation of the vacuum pump, moisture and cold gases in the system enter the pump oil, causing the oil and water to form an emulsion. This not only affects the service life of the pump oil but also deteriorates its maximum pressure capacity. Especially in industrial applications such as pharmaceuticals, food, and ceramics, where vacuum drying is used, the anti-emulsification properties of the pump oil are of particular importance. It has good anti-emulsification properties and a strong ability to separate oil from water. Water vapor and condensed gases are discharged through the vent valve, thereby removing some of the water vapor. Furthermore, low-viscosity pump oil has a better anti-emulsification ability than high-viscosity oil. Oil pumping with additives yields a more significant effect than oil pumping without additives. 　　 5. Antifoam property: During operation, gases in the vacuum system are continuously removed through the oil layer of the vacuum pump. The gases expelled create numerous bubbles on the surface of the oil layer, which then escape through the pump’s exhaust ports, resulting in oil loss and equipment contamination. Adding a defoamer pump oil results in a significant improvement in the defoaming effect. 　　 6. Oxidative stability 　　 Natural mineral oils have their inevitable weaknesses; their heat and oxidation resistance is inferior to that of synthetic oils. The components of these oils deteriorate easily as a result of thermal oxidation, their pressure stability is poor, and their pumping capacity decreases over time as they are used. However, the oxidation stability of the oil with additives is significantly improved compared to pure mineral oil; the D943 oxidation test time for ordinary pure mineral oil is around a few hundred hours, whereas it can increase to over 1,500 hours for the oil with additives. It can be seen that its service life has been extended. 　　 7. Saturated vapor pressure 　　 The saturated vapor pressure is one of the key indicators for vacuum pump oil. In a constant-temperature, sealed container, when the vapor and liquid phases reach dynamic equilibrium, the pressure exerted by the vapor is known as the saturated vapor pressure. At a temperature of 80°C, the value must be at least 6.5×10^-zpa (as the saturated vapor pressure decreases by roughly one order of magnitude for every 20°C increase in temperature). 　　 8. Limit total pressure and limit partial pressures 　　 Limit total pressure: The sum of the pressures generated by all substances (gases) within the vacuum pump, as measured by a Pirani gauge or a thermocouple vacuum gauge. It is understood that abroad, there is currently a focus on the use of indices for full pressure testing. A good oil pumping performance can generally be detected at (1.5×10. kPa). Limit partial pressure: The limit air partial pressure of the pump is measured using a mercury compression vacuum gauge (McLeod gauge); for two-stage rotary vane pumps, this partial pressure should be ≤6×10-5 kPa. The difference between the extreme total pressure and the extreme partial pressure must not be more than one order of magnitude. The greater the difference between the two, the more volatile components are present in the vacuum pump oil, and the worse the quality of the oil becomes. (Note: For the measurement of saturated vapor pressure, ultimate total pressure, and ultimate partial pressure, a two-stage progressive vacuum pump is used as the test pump. ) Usage of vacuum pump oil: Many manufacturers and end-users in China who produce and utilize vacuum pumps are still uncertain about how to choose the appropriate vacuum pump oil. Because, over the past few decades, there has been no way to make a choice when it comes to producing or using any type of vacuum pump – whether it’s a large or small pump, with fast or slow rotation speeds, high or low extreme vacuum requirements, resistance to heat and corrosion, or length of service life, and so on. The only product available on the market is vacuum pump oil. With the advent of compact, high-speed direct-connected vane pumps, \"direct-connected high-speed vacuum pump oil\" was quickly introduced to the market. Under the limitations of the industrial production technology and information environment at that time, apart from a slight improvement in extreme vacuum, no significant improvements were seen in any of the other physical and chemical technical parameters. As a transitional product, it has some significance, but as a true \"direct-connected high-speed vacuum pump oil,\" it has insurmountable flaws. Since the reform and opening up, under the influence of advanced international vacuum technology, Chinese manufacturers of vacuum equipment have begun to pay attention to aspects such as the design of pumps, pumping speed, ultimate total pressure (in China only partial pressures are considered, which is of little practical value to users), noise levels, and sealing materials. At the same time, vacuum pump oil, as an essential component of pumps, has gradually come to receive more attention. Manufacturers of vacuum generation equipment abroad usually have their own specified oils, which are chosen based on different types of pumps and the industries in which they are used, to select the appropriate vacuum pump oil. In this environment, it ensures that the product meets all technical specifications; otherwise, using an inappropriate vacuum pump oil will affect the quality and reputation of the vacuum generation equipment. Shanghai Pingyao Trading Co., Ltd. is the exclusive agent for CPI synthetic lubricants in the Chinese market. It is composed of a group of experts in synthetic oils and professionals in compressors.** Currently, there is one warehouse in the Shanghai Waigaoqiao Free Trade Zone and another in the Putuo area, both of which are stocked with sufficient inventory to serve compressor manufacturers, sellers within China, as well as distributors in the petrochemical industry across various provinces and cities. The main markets include the following areas: @Hydrocarbon compressor oils @Refrigeration compressor oils @Air compressor oils @Compressor oils for refrigerators and freezers @Oils for synthetic equipment @Food-grade lubricants @Food-grade low-temperature heat transfer oils @Oils specifically designed for wind power gearbox use. In the market for synthetic refrigeration oils, the following OEM-approved oils are mainly provided: such as Dunham-Bush, Carrier (Carlyle), Grasso GEA, Century, Copeland, Embraco, BOCK, Maneurop, Danfoss, Mcquay, CIAT, J&E Hall (APV Baker), Trane, Refcomp, Frascold, GRAM, Vilter, Bristol, Clement, and Contour. Praxair, Linde,MESSER, Air Liquide, Mycom, Toromont. CPI Vacuum Pump Oil – The CP-4624-F series is a specially formulated synthetic hydrocarbon lubricant that improves lubricity in high or low temperature conditions and reduces evaporation. It is compatible with mineral oils or equipment designed to use mineral oils, and the CP-4624-F series contains anti-corrosion and anti-oxidation additives. 　　 The CP-4624--F series of products is a long-lasting food-grade lubricant that can be used as a sealing fluid for chemical process pumps, as a lubricant/coolant for compressors, as well as in other applications where improved chemical stability is required. 　　 The CP-4624-F series meets the FDA 21 CFR 178.3570 lubricant specifications, allowing occasional contact with food. 　　　 In the market for synthetic refrigeration oils, the following OEM-designated oils are mainly available: such as Dunham-Bush, Carrier (Carlyle), Grasso GEA, Century, Copeland, Embraco, BOCK, Maneurop, Danfoss, Mcquay, CIAT, J&E Hall (APV Baker), Trane, Refcomp, Frascold, GRAM, Vilter, Bristol, Clement, and Contour. Praxair, Linde,MESSER, Air Liquide, Mycom, Toromont.