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Principle of Check Valve Operation and Classification
Created on 2024.08.05
Check valve: Check valve, also known as a non-return valve or backflow preventer, is used to prevent the backflow of media in a pipeline. The foot valve on a water pump's suction line is also a type of check valve. Its opening and closing components automatically open or close based on the flow and force of the medium, thereby preventing backflow. Check valves are classified as automatic valves and are primarily used in pipelines where the medium flows in a single direction, allowing flow only in that direction to prevent accidents. Structurally, check valves can be divided into three types: lift check valves, swing check valves, and butterfly check valves. Lift check valves can be further categorized into vertical check valves and horizontal check valves. Swing check valves are available in three types: single-petal check valves, double-petal check valves, and multi-petal check valves. Butterfly check valves are straight-through check valves. The aforementioned check valves can be further classified by their connection type into threaded connection check valves, flange connection check valves, and welded check valves.
Attention should be paid to the following matters in the installation of check valves:
1. Do not make the check valve bear the weight in the pipeline, and the large check valve should be supported independently so that it is not affected by the pressure generated by the pipeline.
2. During installation, pay attention to the direction of the medium flow should be consistent with the direction of the arrow indicated by the valve body.
3. The lifting vertical flap check valve should be installed on the vertical pipeline.
4. The lifting horizontal flap check valve should be installed on the horizontal pipeline.
Main performance parameters of check valve:
Nominal pressure or pressure level: PN1.0-16.0MPa, ANSI CLASS150-900, JIS 10-20K, nominal diameter or diameter: DN15~900, NPS 1/4~36, connection: flange, butt welding, thread, socket welding, etc., applicable temperature: -196°C~540°C, body material: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8 (304), CF3 (304L), CF8M(316), CF3M(316L), Ti. With different materials, the check valve can be applied to water, steam, oil, nitric acid, acetic acid, oxidizing media, urea and other media.
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