止回阀：又称逆流阀，逆止阀，背压阀和单向阀。这些阀门是靠管路中介质本身的流动产生的力自动开启和关闭的，属于一种自动阀门。止回阀用于管路系统，其主要作用是防止介质倒流，防止泵及驱动电动机反转，以及容器介质的泄放。止回阀还可用于给其中的压力可能升至超过系统呀的辅助系统提供补给的管路上。主要分为旋启式（依重心旋转）与升降式（沿轴线移动）。1，包装：由于我们的产品90%以上都是出口的，所以一般都采用标准的出口胶合板木箱包装，也有客人采用熏蒸木箱装箱，如果国内使用，也可用一般木箱包装。当然尽量一切满足客户需要。2，售后服务：1），质保期：从出厂日起算18个月，从投入使用日起算12个月。2），返修和更换情形：出现非人为原因造成的质量问题，提供免费返修或者更换；但由于客户用于超过产品本身（其中包括：材质、压力、介质等）的承受能力范围外的工况、介质而引起的质量问题，我们不承担免费返修和更换责任。但是我们可以提供修理帮助，所属费用请客人自己出。谢谢你的谅解 希望合作愉快。所以。在下单 签订合同时，请客人务必详细说明工况。以免造成不必要的麻烦和损失。尽量一步到位。节省你我的时间和资源A check valve allows fluid to flow through it in only one direction. Check valves are two-port valves, meaning they have two openings in the body, one for fluid to enter and the other for fluid to leave. There are various types of check valves used in a wide variety of applications. Although they are available in a wide range of sizes and costs, check valves generally are very small, simple, and/or cheap. Check valves work automatically and most are not controlled by a person or any external control; accordingly, most do not have any valve handle or stem. Design FeaturesSeatFor carbon steel check valve, the seat material is usually forged steel. The sealing surface of the seat is spray welded with hard alloy specified by the customer. Renewable threaded seat is used for NPS≤10 check valves, and welded-on seat is optional. Welded-on seat is used for NPS≥12 carbon steel gate valves. For stainless steel check valve, integral seat is usually applied, or to weld hard alloy directly integrally. Threaded-in or welded-on seat is also optional for stainless steel check valve if required. Body-Bonnet GasketStainless steel + flexible graphite wounded gasket is used for Class150 and Class 300 check valve; stainless steel flexible graphite wounded gasket is used for Class 600 check valve, ring type joint gasket is used for Class 900 check valve; pressure seal design is used for Class1500??Class 2500 check valves. Body-Bonnet ConnectionThe body and bonnet of Class150 to Class 900 check valves are usually with studs and nuts. And the body and bonnet of Class 1500 to Class 2500 check valves are usually of pressure seal design