First, the material
When people buy locks, they are generally worried that the locks will not be durable or the surface will rust or oxidize. This problem is related to the materials used and surface treatment issues.
From a durable point of view, the best material should be stainless steel, especially as a surface material, the more bright it is. It has good strength, strong corrosion resistance and constant color. However, there are many kinds of stainless steel, which can be mainly divided into ferrite and austenite. Ferritic stainless steel has magnetic properties, commonly known as stainless steel. It takes a long time, and the environment is not good, it will rust. Only austenitic stainless steel will not rust. The identification method is very simple. It can be identified with a magnet.
Copper is one of the most widely used lock materials. It has good mechanical properties, good corrosion resistance and processing properties, and its color is beautiful. Especially for copper forged handles and other locks, the surface is flat, the density is good, and there is no air hole. Sand eyes. It is both strong and rust-proof. It can be used for plating various surface treatments such as 24K gold or gold, which is magnificent, noble and generous, adding a lot of color to people's home.
Zinc alloy materials have much lower strength and rust resistance, but have the advantage of being easy to make parts with complex patterns, especially for pressure casting. The locks of the more complicated patterns seen in the market are likely to be made of zinc alloy, and consumers should carefully identify them.
Steel, good strength, low cost, but easy to rust, generally used as the internal structural material of the lock, not suitable for external decorative parts.
Aluminum or aluminum alloy, ordinary aluminum alloy (except aerospace) is soft and light, and the material strength is lower, but it is easy to form.
Second, the surface treatment
Surface treatment refers to covering or forming a protective film on the surface of a part by metal electrodeposition (commonly known as electroplating), painting (called spraying), chemical oxidation (coloring) or other processing methods. The film mainly acts as a preservative, and at the same time increases the aesthetics and durability of the product, which is an important factor for directly measuring the quality of the product. Common methods for measuring surface treatment include: thickness measurement of the cover layer, joint force inspection, salt spray and moisture test, and visual inspection. The coating is applied by methods such as film adhesion, hardness, moisture test, and visual inspection.
Introduction of new standards for door locks in China
The new standard for door locks in China was released in June 2000 and implemented in October 2000. There are 4 national standards for original door lock products. (Including GB8385-97 "outer door lock"; GB8386-87 "ball mortise door lock"; GB8387 - "blade mortise lock" and GB8388-87 "spherical door lock" were converted into QB/ in March 1999 T3837-1999, QB/T3838-1999, QB/T3839-1999 and QB/T3840-1999 were released and implemented in 1988. However, with the continuous development of the market economy, the door lock products have undergone great changes. The variety of products is continuously enriched and the quality level is continuously improved. The original national standards and professional standards are far from meeting the requirements of the door lock quality technology under the new situation. Especially when China's accession to the WTO is imminent, economic global integration is imperative, and the grade and quality of China's door lock products must be improved. In order to keep in line with the international situation, in order to narrow the gap with the developed countries in the world, it is conducive to eliminating trade barriers and increasing foreign exchange earning in exports to promote the development of China's lock industry and participate in international competition. Therefore, the original door lock standards must be revised. The National Light Industry Bureau and the National Daily Hardware Standardization Center issued separate notices to revise the original four door lock standards. The original marble door lock (SG205-80) was combined with the external double-door lock (GB8385-87), and the double-button (tiger) door lock was added to become the standard for the external door lock. The light industry standard QB currently implemented is the revised new standard.
The revised principle of the new standard is: based on the original standard, it can only be improved and not allowed to be lowered. It is necessary to fundamentally reverse the backwardness of China's products with low grades, low prices, and poor technical standards. We will adopt a careful study and a differentiated approach, which will be revised in light of China's actual conditions. In the revision process, different degrees of non-equivalent use of American ANSI (American National Standard) British BS (British National Standard) and JIS (Japanese Industrial Standards) and other foreign advanced standards as the basis. At the same time, in accordance with the requirements of national laws and regulations, combined with the actuality of the products, in the standard revision process, according to different needs, the classification requirements are made. The external door locks and the spherical door locks are divided into two categories, A and B. It distinguishes the difference between a high-class villa, an apartment, a commercial house, and a unit house.
The newly revised standard requirements are higher than the original standard. The A-grade product of the exterior door lock has the B-level of the British BS5872. The B-class product is higher than the original Chinese standard, but lower than the B-class product of the British BS5872. (Note: B-class product ratio in the British BS standard Class A (high), the Class A product in the ball lock, its main indicator is close to the secondary lock level in the US ANSI/BAMA.A156.2-1996. The main indicators of the B-class products are close to the ANSI/BA, A.A156.2-1996 three-level lock level, and a lot higher than the original Chinese standard. Therefore, China's revised new standard QB/T2473-2000, QB/T2475-2000, QB/T2474-2000 and QB/T2476-2000 are higher than the original standard.
Should be considered before purchase
Consumers should consider the following aspects before purchasing a lock.
1. The location used and its importance.
That is, consider using it on a street front door, hall door, room, bathroom or passageway to select a product that suits the desired function.
2. The environment, conditions and requirements for use.
You should consider the advantages and disadvantages of the use of the environment, such as dry humidity, door structure, thickness, left or right door, inner door or outer door to prevent the wrong product.
3. Consider coordination with the decorative environment.
According to your own preferences, the product should be considered for coordination and matching with its living room.
4. Consider the situation of family members
Consider whether there are elderly people, children or people with disabilities in your home and choose products that are convenient for him or her.
5. Consider economic affordability
In combination with the family's economic situation, the economy can afford to buy high-end products, and the economy is less than ideal, and the products with lower grades can be selected. However, regardless of whether high-grade or low-grade products are selected, it is necessary to consider whether the strength of the production enterprises is strong and whether the quality is stable. It is recommended to choose products with quite well-known companies to avoid causing financial losses and unnecessary troubles and troubles for daily life.
6. Consider the reputation and service level of the dealer
Prevent some dealers from recommending some counterfeit and shoddy goods to consumers in their own interests.
How to choose when buying
When purchasing lock products, you should pay attention to the following
1. Products of enterprises with high reputation, stable quality and good after-sales service should be selected.
2. First check whether the logo and logo of the purchased product are complete (including the product's implementation standards, grades, manufacturer's name, address, production date). The package is firm, the contents of the manual are consistent with the product, and the caution is exaggerated. The facts do not match the phenomenon.
3. Observe the appearance quality of the product, including the lock head, lock body, lock tongue, handle and cover plate parts and related accessories. Is the surface color of the plated parts and painted parts bright and uniform, with or without signs of rust and oxidation? And damage.
4. Check whether the product use function is reliable and flexible. Two or more products should be selected for comparison check. Especially when purchasing the two-way lock product, all the keys must be used to test the inner and outer locks separately. You should also check the insurance organization of the product. It is recommended to try each lock at least three times.
5. Then check the tooth condition of the key, such as five key teeth, each key should have not less than three different key teeth, while the first tooth and the fifth tooth should try not to choose the deepest key tooth, which is good for the key. The insertion and removal is not easy to break.
At present, in the process of isolation and preparation of various stem cells from various tissue sources, Centrifuge Tubes with a volume of 15ml and 50ml are used.
It is one of the low-value consumables with high usage rate. It is generally installed on a dry foam rack with the package or in bulk. When used, it is taken out by the operator and placed on the plastic centrifuge tube rack in the ultra-clean workbench. The common centrifuge tube rack can only make the centrifuge tube stand upright. When transferring liquid or needing centrifugation, the operator should hold the centrifuge tube in the left and the night gun or aspirator in the right. If it is necessary to transfer a large amount of liquid reagents or perform gradient centrifugation operations, such as density gradient centrifugation to separate mononuclear cells, the operator needs to hold the centrifuge tube with the right hand for a long time and tilt the centrifuge tube, which often causes the operator's wrist joint pain. At the same time, it will also affect the liquid superposition effect, which will easily lead to the mixing of liquids of different densities, resulting in the failure of the experiment.
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