The main valve is widely used in: steam boilers, liquefied petroleum and gas safety valve seal all copper LPG tank car or rail tankers, production wells, high pressure bypass steam generating equipment, pressure piping, pressure vessels. Valve Co., Ltd. Shandong Everbright valve manufacturer specializing in the production valve manufacturers, welcomed the new and old customers to order our products! Curtain area: When the cylinder valve spring is over the seat A21F Weiqi threaded valve between the sealing surface formed by the surface shape or cone-shaped channel surface area. Discharge area: minimum cross-sectional area of ??the valve discharge fluid channel. For the full revelation safety valve, the discharge area is equal to the flow area; for inching valve discharge area equal to the area of ??the curtain. Valve Co., Ltd. Shandong Everbright valve manufacturer specializing in the production, welcome new and old customers to order our products! A21F safety valve | safety valve | valve model provided by Everbright Everbright Valve Co., Ltd., Shandong. Valve Co., Ltd. Shandong China Everbright (www.sdgdfm.com) strong, credible, Shandong Weifang ball industry has accumulated a large number of loyal customers. The company better work attitude and constantly improving innovative ideas will lead Everbright valve into the brilliant and you work for a better future!