家用燃气表表前阀超温切断装置的设计

Design of Over-temperature Cut-off Device for Front Valve of Domestic Gas Meter

为了在发生火灾时迅速切断户内燃气,提出家用燃气表表前阀超温切断装置的2种设计方案:外置结构超温切断装置和内置结构超温切断装置。分析2种超温切断装置的结构、工作原理、优缺点,介绍感温金属体的技术特性。超温切断装置的切断体锥面密封面与燃气通道锥面形成锥面金属硬密封,可以有效杜绝高温导致软密封材料损坏而密封失效的情况。外置结构超温切断装置的热敏性元件装置对高温感应灵敏、反应迅速;占用燃气通道空间较少,对燃气流量的影响相对较小。内置结构超温切断装置的热敏性元件装置对高温感应时间长、反应不灵敏;占用燃气通道空间较多,导致燃气流量下降明显。采用外置结构超温切断装置的DN 15 mm表前阀,实测流量大于G4. 0规格的家用燃气表最大流量,可适配G1. 6、G2. 5、G4. 0规格的家用燃气表;采用内置结构超温切断装置的DN 15 mm表前阀,实测流量大于G2. 5规格的家用燃气表最大流量,可适配G1. 6、G2. 5规格的家用燃气表。推荐在表前阀选型中,优先采用带外置结构超温切断装置的燃气专用铜球阀。

In order to quickly cut off the indoor gas in the event of a fire,two design schemes for the over-temperature cut-off device for the front valve of the domestic gas meter are proposed: the external structure over-temperature cut-out device and the built-in structure over-temperature cut-out device. The structures,working principles,advantages and disadvantages of two over-temperature cut-off devices are analyzed,and the technical characteristics of temperature-sensitive metal body are introduced. The sealing surface of the cutting body of the over-temperature cutting device and the conical surface of the gas channel form a conical metal hard sealing,which can effectively prevent the damage of the soft sealing material caused by high temperature and the sealing failure. The heat-sensitive element device of the external structure over-temperature cut-off device is sensitive to high temperature and responds quickly. It occupies less space in the gas channel and has a relatively small impact on gas flow. The heat-sensitive element device of built-in structure overtemperature cut-off device has a long sensitive time to high-temperature and is insensitive to the reaction. It occupies more space of the gas channel,which leads to the obvious decrease of gas flow. For the DN15 mm front valve of the gas meter with external structure overtemperature cut-off device,the measured flow rate is greater than the maximum flow of G4. 0 domestic gas meter,and it can be adapted to G1. 6,G2. 5 and G4.0 domestic gas meters. For the DN15 mm front valve of the gas meter with built-in structure over-temperature cut-off device,the measured flow rate is greater than the maximum flow rate of the G2. 5 domestic gas meter,and it can be adapted to the G1. 6 and G2. 5 domestic gas meters. It is recommended that in the selection of the front valve of the meter,the gas-specific copper ball valve with external structure over-temperature cut-off device is preferred.