Regarding the restrictions on valve diameter in engineering regulations
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The following is seen in an engineering regulation: In any case, the valve body grade cannot be lower than the piping technical specifications. The minimum size of the control valve is 1″. 2-1/2″ and 5″ size valves should not be used. Under special circumstances and self-operated pressure regulating valves, valves with a diameter smaller than 1″ can be used, such as 3/4″ and below. The valve seat should be reduced in diameter as needed, and the valve body size should not be less than 2 levels smaller than the pipe diameter. The size of the shut-off valve body is generally the same diameter as the pipe. What I want to ask is, 1. The minimum diameter of the control valve is 1″? Why, there are 1/2 ones too. 2. Why should we not use 2-1/2″ and 5″ valves? 3. Why should the valve body size not be less than 2 levels smaller than the pipe diameter? I hope you all can give me answers.
The caliber selection of the control valve is based on calculations, and sometimes it may not meet the above requirements. 2-1/2″ (DN65) and 5″ (DN125) are uncommon flange specifications, so it is best not to use them.
Your valve cannot be smaller than 1 inch. This may be related to your actual working conditions. The pipe diameter may be too small and easy to block. There are too many valves smaller than 1 inch. We commonly use 1/8 regulating valves. As for the size of the valve, it cannot be smaller than the pipeline level 2. The main reason is that if the diameter is too large, the pressure drop will change too much and the flow rate will change too much, thereby losing the regulating effect of the valve.