The Globe Valve is a valve that is driven by a stem and driven up and down along the axis of the valve seat (sealing surface). It is a widely used Globe Valve that is used to turn on or off the pipe. Not for adjustment. Used for pressure higher caliber smaller working conditions. The valve is characterized by the valve flap along the center line of the valve for linear movement, in the opening and closing seal between the small friction, the height of the valve is small, the valve processing valve than the simple, cut off the valve on the media flow requirements, Bottom up through the valve seat, the main drawback of the valve is the length of the structure, the local resistance is greater, the seal is easy to produce erosion and so on.
The cut-off valve can be divided into straight-through type, that is, its entrance and outlet channel on the same axis, but the internal channel has a turning point in order to arrange the valve seat; DC type, that is, the entrance and outlet on the same axis, and the flow has no direction change Flow resistance is small, the valve seat oblique, also known as Y-type valve; angle, that is, channel entrance and exit axis into 90 °; bellows, that is, instead of the use of bellows stuffing box, which has a good sealing performance; Balanced, that is, inside the channel or outside the channel structure to reduce or balance the upper and lower sides of the valve pressure difference, thereby reducing the opening and closing torque.
The Globe Valve is usually composed of valve body, bonnet, stem, bracket, valve, stem nut, seal packing and drive device. The valve body was drum-shaped, for high-pressure forging body is more rectangular. Most of the threaded connection, the diameter can be used when the flange connection, important occasions available welding; valve cover and the valve body connection is mostly flange connection and screw connection, the upper part of the bonnet stuffing box, bracket is also located in the valve cover, or The valve cover is made into one body; cut-off stem generally in the opening and closing for the rotation movement or lift linear motion; valve is to ensure that the sealing performance of the key parts, with the sealing surface of different petal shape is very different. The sealing surface may be integral with the disc, or it may be otherwise welded; the packing seal is usually provided on the upper part of the bonnet and the packing is pressed with a compression nut or a packing gland.
The use of cut-off valve should follow the principle: ⑴ flow resistance, closing torque, the price is higher than the gate valve, but lower than the metal seal ball valve, less main pipe cut off; ⑵ shape-shaped valve, although reducing the degree of the media, Reduce the flow resistance of the medium, can be used for the main pipe Globe Valve, but other shortcomings are still obvious, is still not the preferred main cut valve; ⑶ almost no temperature and pressure constraints, but because the closing torque, DN250 (NPS10) and above the pipeline, such as the use of the valve must be coupled with the balance of import and export pressure, or the use of high and low approach to avoid the media thrust over the top of the throttle; ⑷ valve opening height and medium flow was (Such as hose station terminal, living water terminal, venting drain terminal, etc .; ⑸ flow channel is complex, scouring serious, should not be used for the need for more accurate control of the flow of the occasion, such as the hose terminal, For the solid particles containing the media conditions; ⑹ folding channel, should not be used for pressure pulsation conditions conditions; not suitable for high pressure oxygen medium conditions; can not be used for the requirements of the ball through the conditions (9) The special stroke of the individual factory is exceptional; (9) Since the stem stroke is shorter than the gate valve and can be made, the valve can not be made Stem lift type, especially suitable for use with the bellows, made of bellows sealing valve, to zero leakage.