船用 JIS 弁の流れの抵抗係数の実態について

抄録

Flow Resistance Research Committee was founded in 1960 by the Ship Machinery Manufacturers' Association of Japan to coordinate the joint research program among shipbuilding companies and valve manufacturers. This paper summarizes the activity of the Committee in the field of JIS valves. The Committee is currently engaged in the experiments on the flow resistance of strainers and heat exchangers. 1. The globe valve. The tested JIS valves totalled 74 numbers. The rated pressure was from 5 to 40 kg/cm^2, and the nominal diameter was from 10 to 130 mm. The flow resistance coefficient ζ as defined by eq. (1) in the text was found to be from 3.5 to 4.8 for 5 kg/cm^2 valves, and from 3.9 to 6.3 for valves for higher pressures. 2. The angle valve. The 30 tested valves were all rated for 5 kg/cm^2, the nominal diameter being from 15 to 130 mm. The measured resistance coefficient was from 1.9 to 2.6. 3. The screw-down check valve. The number of tested valves were 21 for the globe-type and 12 for the angle-type, the nominal diameter being from 25 to 130 mm. It was found that the flow resistance was severely affected by the dynamic pressure of the flowing liquid, because the valve lift was small if the dynamic pressure was not sufficient to raise up the valve to the full-open position. The result of the analysis is presented in the text. 4. The gate valve. The tested 13 valves were all rated for 5 kg/cm^2 pressure, and nominal diameter were from 50 to 130 mm. The resistance coefficient was very small, and was even smaller for larger diameter valves. 5. Also tested were the flow resistance of valves in series, the effect of guide vanes on the valve, the flow resistance of special S-type valves, and so on. Thus, it is concluded that the JIS valve is characterized by the smaller resistance to the flow than the ASA valves and DIN valves. It is hoped that the result obtained will help the shipbuilding industry to reduce the cost and to increase the reliability of the machinery.