1. Because the multi-layer soft and hard stacked sealing ring is fixed on the valve plate, when the valve plate is normally open, the medium forms a frontal scouring on its sealing surface, and the soft sealing belt in the metal sheet interlayer is washed out, which directly affects the sealing performance.
2. Limited by structural conditions, the structure is not suitable for valves with diameters below DN200, because the overall structure of the valve plate is too thick and the flow resistance is large.
3. Due to the principle of the three-bias structure, the sealing between the sealing surface of the valve plate and the valve seat is to press the valve plate to the valve seat by the torque of the transmission device. In the positive flow condition, the higher the pressure of the medium, the tighter the sealing and extrusion. When the medium in the runner is reversed, with the increase of the medium pressure, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, and the seal begins to leak.
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Valve pressure test method - Wuzhong instrument
The commonly used medium for valve pressure test is water, oil, air, steam, nitrogen, etc., and the pressure test methods of various valves are as follows.
(1) Globe valve and throttle valve The strength test of globe valve and throttle valve, usually the assembled valve is placed in the pressure test frame, the valve disc is turned over, and the medium is injected to...
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Wuzhong instrument control valve knowledge
The actuator of the control valve has pneumatic type, electric type and electro-hydraulic linkage type, and the pneumatic equipment is divided into barrier type and cylinder type. Depending on the action when the operating signal and the drive source disappear, the actuator has a forward type, a reverse type, a non-directional type, and a persistent type. The positive type is used in the operation signal and drive ...
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Matters to be paid attention to in the selection of conventional valves - Wuzhong instrument
Valve application requirements
(1) General gate valves, ball valves, and globe valves are prohibited from regulating according to their structural characteristics. However, in process design, it is widely used for mediation. Due to the conditioning application, the valve seal is in a throttling state for a long time, and the impurities in the oil wash the seal, damaging the seal.
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Wuzhong instrument valve classification, two of which are introduced
Classification of valves, types of structures, functional applications, pressure levels, temperature classifications, valve body data classifications, and general classifications
The types of valve products are complex, and the statements are inconsistent, some are divided according to the use (such as chemical valves, oil valves, oilfield valves, power station valves, etc.), and some are according to the medium.
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Precautions for valve selection and drive device - Wuzhong instrument
1. According to the use occasion and use of the valve, confirm the driving method: manual, electric, pneumatic, and hydraulic.
2. Selection of manual methods:
The standard of ball valve and butterfly valve "DN150 can be driven by a handle; Standard DN200 should be used to drive worm gearbox.
b. Gate valve ...
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Pneumatic control valve failure and its causes - Wuzhong instrument
(1) The conditioning valve does not operate. The symptoms and causes are as follows:
1. No signal, no air source. (1) The air source is not opened, (2) because the water contained in the air source freezes in winter, resulting in the blockage of the air duct or the blockage of the filter and pressure reducing valve, (3) the compressor is faulty; (4) Leakage of air source main pipe.
2. ...
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Technical characteristics and structure of single eccentric sealed butterfly valve - Wuzhong instrument
Technical characteristics of single eccentric sealed butterfly valve
In order to solve the extrusion problem of the butterfly plate and the valve seat of the concentric butterfly valve, a single eccentric butterfly valve is produced, and its structural characteristics are that the shaft of the valve stem deviates from the center of the butterfly plate, so that the upper and lower ends of the butterfly plate are not ...
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Wuzhong instrument control valve components
1. Valve body assembly
The valve body assembly shall have the following elements: structural type, nominal diameter, nominal pressure, connection type with pipeline, applicable temperature scale, raw materials of valve body and internals, valve seat diameter or rated flow coefficient, flow characteristics, valve seat leakage grade, etc.
...
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Classification and basic concept of ball valve - Wuzhong instrument
1. Elastic ball valve (i.e. orbital ball valve)
The elastic ball valve is the orbital ball valve, and its ball is elastic. The ball and the seat seal ring are made of metal materials, and the specific pressure of the seal is very large, and the pressure of the medium itself can not meet the requirements of the seal, so it is necessary to apply external force. This...
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Advantages and disadvantages of Wuzhong instrument gate valve
Gate valves have the following advantages:
Low fluid resistance: the medium channel inside the valve body is straight, and the medium does not change its direction of activity when it flows through the gate valve.
The torque required for opening and closing is small;
It can be used on a ring network pipeline where the medium moves in both directions, that is, the flow direction of the medium is not ...
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Regulating valve jamming treatment method - Wuzhong instrument
In the field of industrial automation process control, the conditioning valve, also known as the control valve, is the final control element that changes the process parameters such as medium flow, pressure, temperature, and wave level by means of dynamic operation by bearing the control signal output by the conditioning control unit. It is generally composed of a drive actuator and a valve ...
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Detection instrument (component) and control valve selection principle - Wuzhong instrument
1. High-precision operation, can complete rapid palletizing and destacking operations.
(1). The conditions of the process
Factors such as temperature, pressure, flow, viscosity, corrosiveness, toxicity, pulsation and other factors in the process determine the appearance of the ...
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Wuzhong valve gate valve classification
1. Introduction to gate valves
Gate valve refers to the valve in which the opening and closing parts (rams) move in the straight direction of the medium (channel axis) to complete the opening and closing. Among the various types of valves, gate valves are the most widely used one.
Gate valves are mainly used as shut-off medium in pipelines, i.e. ...
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Standard pressure method for turbine fixed ball valve - Wuzhong instrument
The process of shell experiments and seal experiments done by turbine fixed ball valves in some artificial environments is as follows.
1. The double blocking and discharge function of the turbine fixed ball valve: the turbine ball valve is fixed by using the tension spring preload floating valve seat, when the valve is in two different states of full open and fully closed, the flow ...
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How to choose the control valve of Wuzhong instrument
1. Confirm the selection criteria
(1) Process fluid conditions: fluid name, flow rate, inlet and outlet pressure, pressure difference during normal operation, pressure difference when valve is closed, fluid temperature, specific gravity, viscosity, whether there are suspended solids, fibrous, muddy, etc. Sometimes it is possible to part with the most ...
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Maintenance method of safety valve - Wuzhong instrument
1. The safety valve should have the equipment to prevent the hammer from moving by itself and the guide frame to restrain the lever from deviating, and the tension spring safety valve should have the equipment to improve the handle and prevent the adjustment screws from being twisted at will.
2. It should be installed straight in the pot merchant, the container ...
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The structure of the pressure reducing valve - Wuzhong instrument
Load the organization
The role of the loading tissue is to apply a downward loading force from the top of the pressure reducing valve. The loading structure of the FITOK pressure reducing valve is mainly the loading of tension springs. Tension spring loading has the advantage of reliability and low cost, and is the most versatile loading device in pressure reducing valves.
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The reason for the leakage of the sealing surface of the valve of Wuzhong instrument
1. The sealing surface is uneven and cannot constitute a sealing line:
2. The connection between the valve stem and the closure is suspended, irregular or worn;
3. The valve stem is tortuous or the assembly is not correct, so that the closure is skewed or mismatched:
Fourth, the sealing surface raw materials are not selected properly or not according to the working conditions.
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Maintenance method of safety valve - Wuzhong instrument
1. The safety valve should have the equipment to prevent the hammer from moving by itself and the guide frame to limit the lever from deviating, and the spring-type safety valve should have the equipment to raise the handle and prevent the adjustment screws from being twisted at will.
2. It should be installed straight in the pot merchant, the container ...
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Failure analysis of valve electric actuator - Wuzhong instrument
1. The valve position of the electric actuator is lost:
1) Battery power is lost
When the incremental encoder is selected to measure the stroke, it is necessary for the fulfillment mechanism to have a battery as an auxiliary power supply, the AC power supply disappears, and the change of the valve position of the electric actuator can still be detected by the incremental encoder.
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