止回阀是能自动阻止流体倒流的阀门。止回阀的阀瓣在流体压力作用下开启，流体从进口侧流向出口侧。当进口侧压力低于出口侧时，阀瓣在流体压差、本身重力等因素作用下自动关闭以防止流体倒流。
止回阀一般分为升降式、旋启式等几种类型。
升降式止回阀的结构一般与截止阀相似，其阀瓣沿着通道中心线作升降运动，动作可靠，但流体阻力较大，适用于较小口径的场合。升降式止回阀可分为直通式和立式两种。直通式升降式止回阀一般只能安装在水平管路，而立式升降止回阀一般应安装在垂直管路。
旋启式止回阀的阀瓣绕转轴作旋转运动。其流体阻力一般小于升降式止回阀，它适用于较大口径的场合。旋启式止回阀根据阀瓣的数目可分为单瓣旋启式、双瓣旋启式及多瓣旋启式三种。单瓣旋启式止回阀一般适用于中等口径的场合。大口径管路选用单瓣旋启式止回阀时，为减少水锤压力，最好采用能减小水锤压力的缓闭止回阀。双瓣旋启式止回阀适用于大中口径管路。对夹双瓣旋启式止回阀结构小、重量轻，是一种发展较快的止回阀；多瓣旋启式止回阀适用于大口径管道路。 主要零件材料及性能规范
主 要 零 部 件 | 阀体、阀盖、摇杆 | WCB | CF8 | CF8M | WC6、WC9 | 阀瓣 | WCB堆Cr13或硬质合金 | CF8堆硬质合金 | CF8M堆硬质合金 | WC6、WC9堆硬质合金 | 阀座 | 25堆Cr13或硬质合金 | 304堆硬质合金 | 316堆硬质合金 | 20Cr1MoV堆硬质合金 | 垫片 | 软铁、XB450 | 聚四氟乙烯 | 聚四氟乙烯 | 不锈钢+耐酸石棉缠绕垫 | 螺栓 | 35CrMoA | 35CrMoA | 35CrMoA | 25Cr1Mo1V | 螺母 | 45 | 45 | 45 | 35CrMoA | 主要参数 | 适用介质 | 油品、水、蒸汽 | 硝酸类 | 醋酸类 | 油品、水、蒸汽 | 适用温度 ℃ | ≤425 | ≤200 | ≤200 | ≤550 |
型号 | 公称 通径 NPS(in) | 压力级 Class | 主要结构尺寸(mm) | 阀体 材料 | 性能规范 | D | D1 | L | L1 | H | 适用温度(℃) | 适用介质 | SFH-64C150C | 2" | 150 |
|
| 203 |
| 170 | WCB | ≤425 | 水、油品、蒸气等 | " | 3" | " |
|
| 241 |
| 185 | " | " | " | " | 4" | " |
|
| 292 |
| 215 | " | " | " | " | 6" | " |
|
| 356 |
| 260 | " | " | " | " | 8" | " |
|
| 495 |
| 300 | " | " | " | " | 10" | " |
|
| 622 |
| 350 | " | " | " | " | 12" | " |
|
| 699 |
| 400 | " | " | " | " | 14" | " |
|
| 787 |
| 450 | " | " | " | " | 16" | " |
|
| 864 |
| 480 | " | " | " | " | 18" | " |
|
| 978 |
| 540 | " | " | " | " | 20" | " |
|
| 978 |
| 600 | " | " | " | " | 24" | " |
|
| 1295 |
| 680 | " | " | " | SFH-64C300C | 2" | 300 |
|
| 267 |
| 170 | WCB | ≤425 | 水、油品、蒸气等 | " | 3" | " |
|
| 318 |
| 215 | " | " | " | " | 4" | " |
|
| 356 |
| 235 | " | " | " | " | 6" | " |
|
| 445 |
| 300 | " | " | " | " | 8" | " |
|
| 533 |
| 340 | " | " | " | " | 10" | " |
|
| 622 |
| 350 | " | " | " | " | 12" | " |
|
| 711 |
| 420 | " | " | " | " | 14" | " |
|
| 838 |
| 480 | " | " | " | " | 16" | " |
|
| 864 |
| 520 | " | " | " | " | 18" | " |
|
| 978 |
| 600 | " | " | " | " | 20" | " |
|
| 1016 |
| 670 | " | " | " | " | 24" | " |
|
| 1346 |
| 750 | " | " | " | SFH-64C600C | 2" | 600 |
|
| 292 |
| 175 | WCB | ≤425 | 水、油品、蒸气 | " | 3" | " |
|
| 356 |
| 230 | " | " | " | " | 4" | " |
|
| 432 |
| 295 | " | " | " | " | 6" | " |
|
| 559 |
| 360 | " | " | " | " | 8" | " |
|
| 660 |
| 400 | " | " | " | " | 10" | " |
|
| 787 |
| 460 | " | " | " | " | 12" | " |
|
| 838 |
| 520 | " | " | " | " | 14" | " |
|
| 889 |
| 560 | " | " | " | " | 16" | " |
|
| 991 |
| 650 | " | " | " | " | 18" | " |
|
| 1092 |
| 730 | " | " | " | " | 20" | " |
|
| 1194 |
| 800 | " | " | " | " | 24" | " |
|
| 1397 |
| 900 | " | " | " |
| 
