LPG valve in the steam heating system to play the role of block steam drainage, select the appropriate valve for liquefied petroleum gas, steam heating equipment can achieve maximum efficiency. In order to achieve the best results, it is necessary to all types of LPG valve performance, characteristics of a comprehensive understanding. Many varieties of LPG valves, each with different properties. The selection of liquefied gas valve, the first should choose its characteristics to meet the best operation of steam heating equipment, and then consider other objective conditions, so you need to choose the trap is correct and effective. LPG valve to be able to "identify" steam and condensate in order to play the role of steam blocking drainage. "Identifying" steam and condensate is based on three principles: density difference, temperature difference and phase transition. So on the basis of three principles to create three types of valves for liquefied gas, classified as mechanical type, thermal type, thermal type.