Low-temperature valve length standard -196℃

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The valve cover of low-temperature valves usually adopts a long-neck valve cover structure, which serves to protect the packing box. Because the sealing performance of the stuffing box is one of the key factors for low-temperature valves. If there is a leak in this area, the insulation effect will be reduced, causing the liquefied gas to vaporize. This is because at low temperatures, as the temperature drops, the elasticity of the packing gradually disappears, resulting in a decline in its sealing ability and thus leakage. The leakage of fluid causes freezing at the junction between the packing and the valve stem, which affects the proper operation of the valve stem. Additionally, the up and down movement of the valve stem (which is necessary when opening and closing gate valves and globe valves) can damage the packing, leading to severe leakage. Therefore, low-temperature valves must adopt a long-neck valve cover design. Furthermore, the long neck structure also facilitates wrapping with insulating material to prevent heat loss. The length of the neck of a long-neck valve cover is determined by factors such as the material’s thermal conductivity, heat conduction area, and surface heat dissipation coefficient. At the same time, the required thickness of the insulation layer must also be met. The neck length can be determined using experimental methods; the table below shows the neck length of long-neck valve covers designed by Toyota in Japan based on the operating temperature of low-temperature valves and the thickness of the insulation material. It is also the neck length dimension commonly used for conventional low-temperature valves in the market. http://cdn037.yun-img.com/static/upload/dsc86/news/20171016104211_74143.jpg The length of the neck portion of the long-neck valve cover is taken from the “Practical Valve Design Manual, 3rd Edition”. Minimum operating temperature/°C: -59.4, -101.1, -196. Nominal sizes and neck length T/mm: DN15 NPS1/2: 90, 110, 130; DN20 NPS3/4: 100, 110, 140; DN25 NPS1: 100, 120, 150; DN40 NPS1/2: 110, 130, 160; DN50 NPS2: 110, 130, 170; DN80 NPS3: 120, 150, 190; DN100 NPS4: 130, 160, 200; DN150 NPS6: 140, 170, 220; DN200 NPS8: 140, 170, 220; DN250 NPS10: 150, 180, 240; DN300 NPS12: 150, 180, 240; DN350 NPS14: 160, 190, 250; DN400 NPS16: 160, 190, 250; DN450 NPS18: 160, 190, 250; DN500 NPS20: 170, 200, 260; DN600 NPS24: 170, 200, 260. It should be noted that for some valves, the operating environment has low temperatures while the temperature of the fluid is at normal levels. In such cases, no insulation material is used around the pipes and valves. In this situation, any material suitable for low-temperature conditions can be used for the valve body, and there is no need to increase the length of the neck portion of the valve cover. http://www.dsc86.com/newsdetail_697360.html