straight-through stop valve

I. Product Introduction:
       In straight-through or Y-type stop valves, the flow passage of the valve body forms an oblique line with the main flow passage. This design reduces the degree of flow disturbance compared with conventional stop valves, so the pressure loss through the valve is correspondingly smaller. Straight-through stop valves are particularly suitable for pipelines in the chemical and fertilizer industries; when used with steam, they can prevent medium crystallization. They are widely used in various systems such as petroleum, chemical, metallurgical, and pharmaceutical industries to transport high-viscosity media that solidify at room temperature. Main Technical Parameters: Model Nominal Pressure MPa 1.6 J45H-16 Test Pressure MPa Shell 2.4 Seal 1.6 Working Temperature -30～180℃ Applicable Medium Water Main Part Materials: Model Stem, Bonnet Gray Cast Iron Gray Cast Copper J45H-16 Stem, Disc Carbon Steel Stem Nut Gland Packing Copper Graphite Asbestos Gland Packing Main External Dimensions (Flange dimensions shall comply with JB78 PN1.6MPa standards.)

II. Product Principle:
       Stop valves belong to force-sealed valves. Therefore, when the valve is closed, pressure must be applied to the disc to force the sealing surface to prevent leakage. When the medium enters the valve from below the disc, the resistance that the operating force must overcome includes the friction between the stem and the gland packing, and the thrust generated by the medium pressure. The force required to close the valve is greater than that required to open it, so the stem diameter must be larger; otherwise, the stem may bend. In recent years, since the advent of self-sealing valves, the medium flow direction of stop valves has been changed to enter the valve cavity from above the disc. At this time, under the action of medium pressure, the force required to close the valve is smaller, while the force required to open it is larger, so the stem diameter can be reduced accordingly. Meanwhile, under the action of the medium, this type of valve is also more tightly sealed. China's valve "Three Modernizations for Supply" regulations once stipulated that the flow direction of stop valves must be from top to bottom.

III. Product Features:

1. During the opening and closing process, the friction on the sealing surface is smaller than that of gate valves, making it wear-resistant.

2. The opening height is small.

3. Usually, there is only one sealing surface, with good manufacturing process and easy maintenance.

IV. Main Technical Parameters:

V. Main Part Materials:

VI. Operation and Maintenance:

The purpose of operation and maintenance is to extend the valve service life and ensure reliable opening and closing. The stem thread frequently rubs against the stem nut, so it is necessary to apply a small amount of grease, molybdenum disulfide, or graphite powder to play a lubricating role. Valves that are not opened and closed frequently should also rotate the handwheel regularly and add lubricant to the stem thread to prevent seizing. For outdoor valves, a protective sleeve should be added to the stem to prevent rust and contamination from rain, snow, and dust. If the valve is mechanically driven, lubricant should be added to the gearbox on schedule. The valve should always be kept clean. Regular inspection should be conducted to maintain the integrity of valve components. If the fixing nut of the handwheel falls off, it must be replaced with a complete one; it cannot be used makeshift, otherwise, the square part on the upper part of the stem will be worn, gradually losing fitting reliability and even making the valve unable to operate. Do not support other heavy objects with the valve, and do not stand on the valve. The stem, especially the threaded part, should be wiped frequently, and the lubricant contaminated by dust should be replaced with new one, because dust contains hard impurities that easily wear the threads and stem surface, affecting the service life.