According to the "petrochemical fire protection design" (GB50160-92) provides: "A, B liquid fixed roof tanks, flame arrester should be located and breathing valve", and our breathing valve single type of product, but also failed to meet the petrochemical each department's needs. In order to solve the above problem, Sinopec Beijing Design Institute developed the HX series of new products. The product has a type, complete specifications, compact, light weight, ventilation volume, leakage is small. Products with a single call valve, single suction valve, breathing valve, various structural types can be constructed with flame arrester combination can also be required to take over the preparation.