【 Weak current College 】 heating and gas supply-section IV-gas supply

This kind of out of gas, city gas supply mode, indoor gas pipeline and gas appliances, and other aspects of the introduction of a gas supply system of related content. 　　As part of the property, equipment and facilities required by learning on the gas supply of knowledge has a more comprehensive understanding, particularly for indoor laying of gas pipeline system and its features and requirements of the relevant content to master. Urban gas supply system is a complex, comprehensive facilities, is one of the city symbol of modernization. Gas is a gas fuel with high thermal efficiency, temperature is high, the easy-to-adjust flame size, convenience, there is no ash during combustion, health conditions, and you can use pipeline transport or supply bottles, etc. Gas and air mixture to the certain proportion, easily lead to combustion and explosion, fire risk considerably; manufactured gas with toxicity.　　To prevent the use of risk and poisoning occurred, for gas equipment, gas piping system design and installation, there are strict requirements. A type of gas, gas can be divided into artificial gas, LPG and natural gas in three categories, as described below.　　Gas separation and processing components other manufactured gas in coal as raw materials manufactured gas called coal gas to oil as raw material, made of oil-gas gas called contains hydrogen sulfide, ammonia, benzene, and tar and other impurities supply cities of manufactured gas requirements minimum calorific value in 14654kJ/Nm3 above LP on oil for machining process of a mixture of flammable gases mainly propane, propylene, currently (and different) butane, forward (hetero) butene and reverse (CIS), in the standard State of butene is gas, when the temperature falls below a critical value or pressure rise to a certain value is liquefied natural gas from the drilling mined combustible gas is methane, liquefaction of the gaseous mass is 1/600 when you use a non-toxic when joining and the smell of gas (such as ethyl mercaptan), in order to detect leakage, avoid poisoning or combustion and explosion, accident, how urban gas supply is divided into urban gas supply pipe and bottled. 1. pipeline transportation of natural gas or manufactured gas after cleaning, you can enter the town gas network. Under the pressure of the gas network in different towns can be divided into the following several. ① voltage distribution system P ≤: 4.9kPa (P: for conveying pressure). ② pressure pipeline network: P 4.9kPa "≤ 147.15kPa. ③ high pressure pipeline network: P 147.15kPa "≤ 294.3kPa. 　　④ high pressure pipeline network: P 294.3kPa "≤ 784.8kPa.　　Town gas network including street gas network and community of gas network in two parts. In the supply area of larger large cities, streets, gas network may use high pressure pipeline network or high pressure pipeline network for long distance transmission; in small towns, generally use low voltage network in,.　　Gas pipeline from street high pressure or high pressure pipeline network after pressure regulating station, into the streets of pressure pipeline network, and then through the area of gas pressure regulating station, into the streets and low voltage distribution system, then by the community network access users.　　2. bottled supply LPG use bottled, storage and distribution station (bottle filling station) set spherical tanks, through certain equipment to tanks LPG grouted with cylinders, supply station supply users. According to the size of the gas can be used with single bottle or flask set of gas supply. One single bottle of supply adopted certain weight (such as household 15kg) cylinder a, together with the use of gas supply; cylinder group is supplied to the cylinder parallel .for smaller user units. Steel bottle of liquid petroleum gas saturated vapor pressure in absolute pressure is 70 ~ 800kPa, at room temperature can be natural vaporizing.　　When used for gas, the pressure and vacuum cylinder to 2.8 ± 0.5kPa.　　3, indoor gas pipeline 1. piping system for interior gas pipeline system by the introduction of pipe, risers and pipes. Indoor gas pipeline in the use of water-gas pipes, it belongs to the low pressure pipe. Adoption of the whorl pipelines (threads).　　Buried portion should be coated with preservatives, downlead pipeline adopts the galvanized pipe, pipe leak is not allowed.　　Indoor gas pipeline requires the downlead, specific requirements for the installation of equipment and facilities management of the property.　　In the likely freeze, indoor gas pipelines should be heaving. 2. gas meter gas meter is the measurement of gas consumption of the instrument.　　At present, China's favorite is a dry skin gas flow table, it is suitable for indoor and low pressure gas supply system. 4, gas appliances, depending on its purpose, there are several gas appliances. Residential common gas gas stove with kitchen and gas water heater, etc. ① kitchen gas stove: common double huoyan gas range. It consists of the furnace, the face and burner consists of three parts. ② gas water heater: a local supply of hot water heating equipment. 　　 　　When building without centralized hot water supply, can use gas as a heat source, through the preparation of hot water heater. As gas combustion emissions contains carbon monoxide, a gas-fired appliances, room should be equipped with appropriate ventilation. Specification provides for gas water heaters must not be directly installed in the bathroom.