Closing valve opening and closing pieces of plug-shaped flap, the sealing surface was flat or tapered surface, the valve flap along the fluid center line for linear motion. Stem movement form, lifting rod (stem lift, hand wheel does not lift), there are lifting rotary rod (hand wheel with the stem rotating together, the nut is located in the valve body). Globe valve only applies to fully open and fully closed, does not allow for regulation and throttling. Bellows globe valve 100% pressure test, all to zero leakage. As a secondary seal, the stuffing box remains on top of the bellows, adding even greater reliability and safety. High-pressure valve metal bellows are multi-layer structure, through the hydroforming, can guarantee the maximum pressure 10000 times the entire trip on / off life. The key components - metal bellows, lower end and stem assembly with automatic seam welding, the upper end and the connecting plate automatic seam welding, the fluid medium and the atmosphere to form a metal barrier to ensure zero stem leakage. Valve and valve body sealing surface after precision grinding, assembled through the use of Advantages: 1, double the seal design (bellows + packing) If the bellows failure, stem packing will also avoid leakage, and in line with international standards for sealing. 2, safety and environmental protection, no fluid loss, reduce energy losses, improve plant equipment safety. 3, long service life, reduce the number of maintenance, reduce operating costs. 4, rugged bellows seal design to ensure zero stem leakage, providing maintenance-free conditions. Use: Suitable for thermal oil, toxic, flammable, highly permeable, pollute the environment, with radioactive fluid medium pipeline for the cut-off valve, can also be used for regulation, is to create a leak-free factory quality products. The valve casting all cast precision. Stop valves are forced to seal the valve, so the valve is closed, the pressure must be applied to the valve flap to force the sealing surface does not leak. When the medium from the bottom of the valve into the valve six, the operating force needed to overcome the resistance is the stem and packing friction and the pressure generated by the media thrust, off the valve force than the valve opening force, so the valve The diameter of the rod should be large, otherwise it will happen to the top of the valve stem failure. In recent years, since the self-sealing valve appears, the cut-off valve of the media flow to change over from the top of the valve into the valve cavity, then under medium pressure, the valve closing force is small, and open the valve force, the valve stem The diameter can be reduced accordingly. At the same time, in the medium, this form of valve is also more stringent. China's valve "three to" have provided that the flow of the valve, all from top to bottom. When the valve is open, the valve opening height, 25% to 30% of the nominal diameter, the flow has reached its maximum, indicating that the valve has reached the fully open position. Therefore, the full-stop position of the valve, valve stroke should be determined. Globe valve has the following advantages: 1. Simple structure, manufacturing and maintenance more convenient. 2 small work schedule, opening and closing time is short. 3. Good sealing, sealing surface friction, longer life expectancy. The shortcomings of the cut-off valve are as follows: 1. Fluid resistance is large, the required force is large when opening and closing. 2 does not apply to particles with a larger viscosity, easy to caking medium. 3. Adjust the performance is poor. Shut-off valve installation and maintenance should note the following: 1. Handwheel, handle operated shut-off valve can be installed in any position on the pipeline. 2. Handwheel, handle and Wei moving mechanism, do not allow lifting. 3. The flow direction of the medium should be the same as the arrow direction of the valve body.
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