MAPP is colorless in both liquid and gas form. The gas has a pronounced acetylene-like or fishy odor at concentrations above 100 ppm, due to the addition of substituted amines as a polymerization inhibitor. Low molecular weight alkynes have strong odors. Mapp Gas is toxic if inhaled at high concentrations. Mapp gas is a mixture of various hydrocarbons, principally, methylacetylene , propadiene and Propane(MAPP). It produces a relatively hot flame (2,976°C) with a high heat release in the primary lame (inner cone) (15,445kJ/m 3 ), less than for acetylene (18,890kJm 3 ) but much higher than for propane (10,433kJm 3 ). The secondary flame (outer cone) also gives off a high heat release, similar to propane and natural gas. The combination of a lower flame temperature, more distributed heat source and larger gas flows compared with acetylene results in a substantially slower pierce time. Mapp Gas Mapp Gas,Mapp Gas Torch,Mapp Torch,Mapp Gas Temp ZHEJIANG ICE LOONG ENVIRONMENTAL SCI-TECH CO.,LTD. , https://www.china-refrigerantgas.com
Due to the structure of the human eye, we can only see the range of about 150 degrees in front of the eye and 140 degrees in the longitudinal direction. Therefore, watching TV is as simple as watching TV at a viewing angle of 40 degrees above and 40 degrees, and around 60 degrees. This look and feel is already fine. According to current television, almost all LCD TVs have a 16:9 widescreen design. If a wide screen is close to the camera, it will be distorted in the left and right visual range, and the viewing effect cannot be optimized. .
Best viewing distance = LCD diagonal length × 2 (this is the closest viewing distance) / × 3 (this is the farthest viewing distance)
Maximum TV size (inch) = viewing distance (cm) ÷ 3.736
The minimum TV size (inch) = viewing distance (cm) ÷ 6.227
Xiao Bian has compiled the best viewing distance for each size for everyone: 
50-inch LCD TV purchase
1. According to the living room area to buy a 50-inch LCD TV
The larger the TV screen, the corresponding viewing distance will increase. A 50-inch LCD TV is placed in a small living room. I am afraid that it looks asymmetrical and even worse than display. The most reasonable distance to watch TV is to ask people to see every corner of the TV without turning their eyes and head. The best viewing distance is about 4.5 meters for a 50-inch LCD TV. Left and right, such a distance is like a fantasy in a small living room. 
2. According to the price of 50-inch LCD TV to buy
Since ancient times, commodity prices have been the absolute factor affecting the transaction rate, and 50-inch LCD TVs are no exception. Therefore, regardless of the purchase of any product, most consumers will not directly ask about the quality of the product, but first ask how the price is. It can be seen that the cost-effectiveness of the importance of a product, often see a lot of TV brands discounted activities, seemingly cut the price of thousands of dollars, but the actual price is still prohibitive, a 50-inch LCD TV size screen Flat-panel TVs, basically all belong to the brand's high-end products, prices are basically above 10,000 yuan. 
3. According to the 50-inch LCD TV accessories to buy
Many families buying flat-screen TVs are hanging TVs on the wall, which is not only beautiful, but also saves space. However, a 50-inch LCD TV is said to have a weight of tens of kilograms. A heavier weight may reach 50 kilograms. Its weight is equivalent to the weight of four 1.5-hp split air conditioners. If the installation is not good, the consequences are very serious.
However, to install and hang a good 50-inch LCD TV, its accessories requirements are very high, especially the quality of the wall bracket must be better, and must undergo rigorous calculations and repeated testing, both in terms of strength and durability can be achieved Required.
50-inch LCD TV viewing distance and purchase [Guide]
Now people are more important to health than anything else, and we watch TV is also about the health of our eyes. We not only need to see clearly, but we must also be able to protect our eyes. Therefore, the viewing distance of television becomes extremely important. Today, Xiaobian discusses the viewing distance of the 50-inch LCD TV and its buying guide.