Classification of check valves

Check valve refers to a valve that automatically opens and closes the valve disc by relying on the of the medium itself to prevent the medium from flowing in reverse. It is also known as a non-return valve, one-way valve, backflow valve, and back valve, and belongs to the category of automatic valves. There are various ways to classify it, and the following is a common classification introduction: Classification by structure L check valve: The valve body shape is the same as that of a gate valve, and the fluid resistance is relatively large. When the medium flows in the forward direction the valve disc opens by the thrust of the medium; when the medium stops flowing, the valve disc falls on the valve seat by its own weight. It can be into vertical and horizontal types. Vertical lift check valve: The direction of the medium inlet and outlet channel is the same as that of the valve seat channel, and the resistance is smaller than that of the straight-through type, which is installed in the vertical pipeline. Straight-through lift check valve: It can only be installed in the horizontal, and it is often used in small diameter occasions DN50 due to the limitation of installation requirements. Swing check valve: The valve disc is disc-shaped and around the valve seat channel’s rotating shaft. Since the valve’s internal channel is streamlined, the flow resistance is smaller than that of the lift check valve. It is for small and medium-sized pipes with low pressure and large diameter (low flow rate and large diameter occasions with frequent changes in flow), but its sealing performance is not as as that of the lift type. It is divided into single-disc, double-disc, and multi-disc types. These three forms are mainly divided according to the valve’s diameter, aiming to prevent the medium from stopping or flowing in reverse, to weaken the hydraulic impact, and the installation position is not limited. It can be installed on, vertical, or inclined pipelines. Single-disc swing check valve: It is generally suitable for medium-sized diameter occasions. When used in large-diameter pipelines, it is to use a slow-closing check valve that can reduce water hammer pressure to reduce water hammer pressure. Double-disc swing check valve: It is suitable for large and medium diameter pipelines. The clamp-type double-disc swing check valve has a small structure and light weight, and it is a rapidly developing check valve. Multi-disc swing check valve It is suitable for large-diameter pipelines. Butterfly check valve: It is a straight-through type, and its structure is similar to that of a butterfly valve It has a simple structure, low flow resistance, and low water hammer pressure. Diaphragm check valve: There are several structural forms, all of which use aaphragm as the opening and closing part. Because of its good water hammer resistance performance, simple structure, and low cost, it has developed rapidly in recent years, its use temperature and pressure are limited by the diaphragm material. Ball-shaped sewage check valve: The valve body adopts a full-channel structure, which has the advantages large flow and low resistance. It uses a round ball as the valve disc and is suitable for industrial and domestic sewage pipeline networks with high viscosity and suspended matter. Classification connection form It can be divided into three types: threaded connection, flange connection, and welding. Classification by material The main material of the check valve is, such as WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8(34), CF3(304L), CF8M(316), CF3M(316L), Ti, etc. By using different, the check valve can be used for water, steam, oil, nitric acid, acetic acid, oxidizing media, urea, and other media. by function NRVZ silent check valve NRVG silent check valve NRVR silent check valve SFCV rubber disc non-return valve DDCV-disc non-return valve Other classifications Check valves can also be divided into bellows type, diaphragm type, ultra-thin film type, heavy hammer type exposed type, screw rod type, etc. according to their structural forms, which are suitable for different occasions. Bellows check valve: It is suitable for chemical, industry, food, pharmaceutical, sewage treatment, and other industries. Diaphragm check valve: It is suitable for petrochemical and flat warehouse