止回阀：止回阀又称单向阀或逆止阀，其作用是防止管路中的介质倒流。水泵吸水关的底阀也属于止回阀类。启闭件靠介质流动和力量自行开启或关闭，以防止介质倒流的阀门叫止回阀。止回阀属于自动阀类，主要用于介质单向流动的管道上，只允许介质向一个方向流动，以防止发生事故。止回阀按结构划分，可分为升降式止回阀、旋启式止回阀和蝶式止回阀三种。升降式止回阀可分为立式和卧式两种。旋启式止回阀分为单瓣式、双瓣式和多瓣式三种。蝶式止回阀为直通式、以上几种止回阀在连接形式上可分为螺纹连接、法兰连接和焊接三种。主要零件材料零件名称材料牌名阀体WCBZGCr5MoZG1Cr18Ni9TiZG1Cr18Ni12Mo2Ti阀盖WCBZGCr5MoZG1Cr18Ni9TiZG1Cr18Ni12Mo2Ti阀瓣WCBZGCr5MoZG1Cr18Ni9TiZG1Cr18Ni12Mo2Ti销轴2Crl32Crl31Cr18Ni9Ti1Cr18Ni12MO2Ti垫片石墨缠绕垫片石墨缠绕垫片聚四氟乙稀缠绕垫片聚四氟乙稀缠绕垫片型号性能规范公称压力PN（MPa）壳体材料试验压力(Mpa)WCBZGCr5Mo(C5)ZG1Cr18Ni9TiZG1Cr18Ni12Mo2Ti强度试验液体密封气体密封1.6H44H-16CH44Y-16IH44W-16PH44W-16R2.41.82.5H44H-25H44Y-25IH44W-25PH44W-25R3.82.84.0H44H-40H44Y-40IH44W-40PH44W-40R6.04.46.4H44H-64H44Y-64IH44W-64PH44W-64R9.67.110.0H44H-100H44Y-100IH44W-100PH44W-100R15.011.0适用温度-29-425℃≤550℃-40-200℃-40-200℃超出温度范围，请订货时注明适用介质水蒸气、油品等水蒸气、油品等硝酸等醋酸等连接尺寸和外形尺寸型号公称通径尺寸（mm）LDD1D2D6bZ-фdD0HH44H-16C4020014511085-164-ф1816015050230160125100-164-ф1818516065290180145120-184-ф1821517580310195160135-208-ф18230180100350215180155-208-ф18260210125400245210185-228-ф18320235150480280240210-248-ф23350250200550335295265-2612-ф23420330250650405355320-3012-ф25480380300750460410375-3012-ф255204103508505204870435-3416-ф25600490H44H-254020014511085-184-ф1816015050230160125100-204-ф1818516065290180145120-228-ф1821517580310195160135-228-ф18235185100350230190160-248-ф23270220125400270220188-288-ф25340248150480300250218-308-ф25375276200550360310278-3412-ф25435350250650425370332-3612-ф30515410300750485430390-406-ф30550430350850550490448-4416-ф34620466H44H-4040200145)