Reading Braille: Braille Instructions,Braille Alphabet,Braille Printing,Braille Packaging Box Shanghai Caide Printing Co.,Ltd. , https://www.caideprinting.com
For example, these general physical and chemical properties are as follows:
1. Familiarize yourself with the Braille alphabet, which consists of six dots arranged in two columns of three dots each. Each dot or combination of dots represents a different letter, number, punctuation mark, or special symbol.
2. Place your fingertips lightly on the Braille text, typically on a page or surface made specifically for Braille.
3. Feel the dots with your fingertips and identify the patterns to determine the corresponding letters, numbers, or symbols.
4. Move your fingertips systematically across the Braille text, reading from left to right and top to bottom, just like reading regular text.
Writing Braille:
1. Learn the Braille alphabet and practice writing each letter, number, punctuation mark, and special symbol.
2. Use a Braille slate and stylus, which is a tool specifically designed for writing Braille. The slate has rectangular openings to hold the paper, and the stylus is used to press the dots onto the paper through the openings.
3. Place a piece of Braille paper or cardstock into the slate, ensuring it is aligned properly.
4. Hold the stylus like a pen or pencil and press the appropriate dots onto the paper, one at a time, following the Braille alphabet.
5. Lift the stylus after each dot is pressed to avoid smudging or blending the dots together.
6. Continue writing the desired text, moving from left to right and top to bottom on the paper.
7. Review your writing by feeling the dots with your fingertips to ensure accuracy.
It is important to note that learning Braille may require time and practice, as it is a tactile skill that requires the ability to distinguish between the different dot patterns. However, with dedication and persistence, individuals can become proficient in reading and writing Braille.
Lubricant knowledge
First, the air compressor lubrication
Lubricating oil is used in various types of machinery to reduce friction and protect the mechanical and processing parts of liquid lubricants, mainly for lubrication, cooling, rust prevention, cleaning, sealing and buffering. Lubricating oil accounts for 85% of all lubricating materials, and there are many types of products. Now the world uses about 38 million tons. The general requirements for lubricants are:
(1) Reduce friction and anti-wear, reduce frictional resistance to save energy, reduce wear and tear to prolong mechanical life and improve economic efficiency;
(2) Cooling, it is required to discharge the friction heat outside the machine at any time;
(3) Sealed, required to prevent leakage, dust, and suffocation;
(4) Anti-corrosion and anti-rust, it is required to protect the friction surface from oil deterioration or external erosion;
(5) Clean and flush, it is required to clean the friction area scale;
(6) Stress dispersion buffering, dispersing load and mitigating shock and shock absorption;
(7) Kinetic energy transmission, hydraulic system and remote control motor and friction stepless speed change.
Second, the composition of lubricating oil
Lubricating oils generally consist of two parts, a base oil and an additive. Base oil is the main component of lubricating oil, which determines the basic properties of lubricating oil. Additives can make up for and improve the performance of base oil, and give some new properties. It is an important part of lubricating oil.
1. Lubricating base oil
Lubricating base oils are mainly divided into mineral base oils and synthetic base oils. Mineral base oils are widely used and used in large amounts (more than 95%), but in some applications they must be formulated with synthetic base oils, thus allowing the rapid development of synthetic base oils. Mineral oil base oil is refined from crude oil. The main production processes of lubricating base oils include: atmospheric and vacuum distillation, solvent deasphalting, solvent refining, solvent dewaxing, white clay or hydrogenation supplementation. In 1995, China revised the current lubricant base oil standard, mainly revised the classification method, and added two types of special base oil standards for low-condensation and deep refining. For the production of mineral-based lubricants, the most important thing is to choose the best crude oil. The chemical composition of mineral base oils includes high boiling, high molecular weight hydrocarbons and non-hydrocarbon mixtures. Its composition is generally alkanes (straight chain, branched chain, multi-branched chain), cycloalkanes (monocyclic, bicyclic, polycyclic), aromatic hydrocarbons (monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons), cycloalkyl aromatic hydrocarbons, and oxygen and nitrogen , sulfur-containing organic compounds and non-hydrocarbon compounds such as gums and asphaltenes.
2, additives
Additives are the essence of modern high-grade lubricants. Proper selection of reasonable additions can improve their physical and chemical properties, impart new special properties to lubricants, or enhance their original properties to meet higher requirements. According to the quality and performance of the lubricant requirements, careful selection of additives, careful balance, and reasonable deployment are the key to ensuring the quality of the lubricant. Commonly used additives are: viscosity index improver, pour point depressant, antioxidant, detergent dispersant, friction moderator, oil agent, extreme pressure agent, anti-foaming agent, metal passivator, emulsifier, anti-corrosion agent, anti- Rust, demulsifier.
Third, the basic performance of lubricating grease
Lubricating oil is a technology-intensive product that is a mixture of complex hydrocarbons whose true performance is a combination of complex physical or chemical processes. The basic properties of lubricating oils include general physical and chemical properties, special physical and chemical properties and simulated bench tests.
General physical and chemical properties
Each type of grease has its common general physical and chemical properties to indicate the inherent quality of the product. Correct
(1) Appearance (Chroma) The color of the oil often reflects the degree of refinement and stability. For base oils, the higher the degree of general refining, the cleaner the oxides and sulfides of the hydrocarbons and the lighter the color. However, even if the conditions of refining are the same, the color and transparency of the base oil produced by different oil sources and base crude oils may be different. For the new finished lubricants, color has lost its original meaning as an indicator of the degree of refining of the base oil due to the use of additives.
(2) Density density is the simplest and most commonly used physical property indicator of lubricating oil. The density of lubricating oil increases with the increase of the amount of carbon, oxygen and sulfur in its composition. Therefore, in the case of the same viscosity or the same relative molecular mass, the lubricating oil containing more aromatics and containing more colloidal and asphaltenes It has the highest density, is mostly centered on naphthenes, and contains the smallest amount of alkanes.
(3) The viscosity viscosity reflects the internal friction of the oil and is an indicator of the oiliness and fluidity of the oil. Under the premise of not adding any functional additives, the higher the viscosity, the higher the oil film strength and the worse the fluidity.
(4) Viscosity Index The viscosity index indicates the degree to which the viscosity of the oil changes with temperature. The higher the viscosity index, the smaller the viscosity of the oil is affected by the temperature, and the better the viscosity-temperature performance, and vice versa.
(5) The flash point flash point is an indicator of the evaporability of the oil. The lighter the fraction of the oil, the greater the evaporability and the lower the flash point. Conversely, the heavier the fraction of the oil, the lower the evaporability and the higher the flash point. At the same time, the flash point is an indicator of the risk of fire in petroleum products. The hazard level of the oil is divided according to the flash point. The flash point is flammable below 45 °C, and the flammable is above 45 °C. It is strictly prohibited to heat the oil to its flash point during storage and transportation of the oil. . In the case of the same viscosity, the higher the flash point, the better. Therefore, the user should choose the lubricating oil according to the operating temperature and working conditions of the lubricating oil. It is generally believed that the flash point is 20 to 30 ° C higher than the use temperature and can be safely used.
(6) The freezing point and the pour point freezing point are the highest temperatures at which the oil stops flowing under the specified cooling conditions. The solidification of the oil is very different from the solidification of the pure compound. Oil does not have a clear solidification temperature. The so-called "coagulation" only loses fluidity as a whole, and not all components become solid. The freezing point of the lubricating oil is an important quality indicator indicating the low temperature fluidity of the lubricating oil. It is important for production, transportation and use. Lubricating oils with high freezing points cannot be used at low temperatures. Conversely, in areas with high temperatures, it is not necessary to use low-condensation lubricants. Because the lower the freezing point of the lubricating oil, the higher the production cost, resulting in unnecessary waste. In general, the freezing point of the lubricating oil should be 5~7 °C lower than the lowest temperature of the environment. However, it should be mentioned in particular that when selecting a low-temperature lubricating oil, it should be considered in combination with the freezing point, low-temperature viscosity and viscosity-temperature characteristics of the oil. Because of the low-condensation point, the low-temperature viscosity and viscosity-temperature characteristics may not meet the requirements. Both the freezing point and the pour point are indicators of the low temperature fluidity of the oil. There is no principle difference between the two, but the measurement method is slightly different. The freezing point and pour point of the same oil are not completely equal. Generally, the pour point is higher than the freezing point by 2 to 3 ° C, but there are exceptions.
(7) Acid value, base value and neutralization value The acid value is an index indicating that the lubricating oil contains an acidic substance, and the unit is mgKOH/g. The acid value is divided into two types: strong acid value and weak acid value. The combination of the two is the total acid value (referred to as TAN). What we usually call "acid value" actually means "total acid value (TAN)". The base number is an index indicating the content of the alkaline substance in the lubricating oil, and the unit is mgKOH/g. The base number is also divided into two types: strong base value and weak base value. The combination of the two is the total base number (TBN). What we usually call "base value" actually means "total base number (TBN)". The neutralization value actually includes the total acid value and the total base number. However, unless otherwise stated, the term "neutralization value" generally refers to only "total acid value", and its unit is also mgKOH/g.
(8) Moisture Moisture is the percentage of water content in the lubricating oil, usually in weight percent. The presence of moisture in the lubricating oil destroys the oil film formed by the lubricating oil, deteriorating the lubricating effect, accelerating the corrosive action of the organic acid on the metal, and corroding the equipment, so that the oil is liable to cause sediment. In short, the less moisture in the lubricating oil, the better.
(9) Mechanical impurities Mechanical impurities are precipitates or colloidal suspensions that are insoluble in solvents such as gasoline, ethanol and benzene. Most of these impurities are sandstone and iron filings, as well as some organic metal salts which are insoluble in solvents by additives. Generally, the mechanical impurities of the lubricating base oil are controlled to be 0.005% or less (the machine is considered to be none below 0.005%).
(10) Ash and sulphated ash Ash refers to the non-combustible material remaining after burning under specified conditions. The composition of ash is generally considered to be some metal elements and their salts. Ash has a different concept for different oils. For base oils or oils without additives, ash can be used to determine the depth of refining of the oil. For oils (new oils) with metal salt additives, ash is a means of quantitatively controlling the amount of additive added. Sulfuric acid ash is used abroad instead of ash. The method is: adding a small amount of concentrated sulfuric acid before burning and ashing of the oil sample to convert the metal element of the additive into sulfate.
(11) Residual charcoal oil Under the specified experimental conditions, the charred black residue formed by heat evaporation and combustion is called carbon residue. Carbon residue is an important quality indicator of lubricating base oil, which is for judging