Control Valve

In modern automatic control, the control valve plays a very important role. The proper distribution and control of flowing liquid, gas, or solid powder requires a control valve to complete. The low-pressure pneumatic conveying device uses a blower as a power source, and the fan is at the front end of the feeding device, and the powder in the silo continuously goes high through the feeding device. In modern automatic control, the control valve plays a very important role. The proper distribution and control of flowing liquid, gas or solid powder requires a control valve to complete. The low-pressure pneumatic conveying device uses a blower as a power source, and the fan is at the front end of the feeding device, and the powder in the silo is continuously and uniformly fed to the high-speed airflow through the feeding device, so that the powder is transported in a suspended state. In the pneumatic conveying device, it is necessary to control the material flow rate through the control valve, determine the settling speed of the material and the mass of the material delivered …

Research and analysis of the flow control valve Read More »

1. INCREASE THE STIFFNESS METHOD For oscillation and slight vibration, the stiffness can be increased to eliminate or weaken. For example, it is feasible to use a spring with a large stiffness and a piston actuator. 2.  INCREASE THE DAMPING METHOD Increasing the damping increases friction against vibration. For example, the valve plug of the sleeve valve can be sealed with an “O” ring, and a graphite filler with a large frictional force is used, which has a certain effect on eliminating or attenuating a slight vibration. 3. INCREASE THE GUIDE SIZE, REDUCE THE FIT GAP METHOD Shaft plug valves generally have small guide sizes, and all valve fit clearances are generally large, 0.4 to 1 mm, which is helpful for generating mechanical vibration. Therefore, when a slight mechanical vibration occurs, the vibration can be weakened by increasing the guide size and reducing the fit clearance. 4. CHANGE THE SHAPE OF THE THROTTLE, ELIMINATE THE RESONANCE METHOD Because the so-called vibration source of the control valve occurs in the throttle port with high speed and sudden change of pressure, changing …

8 ways to solve the vibration problem of the control valve Read More »

DRIVING ENERGY The most commonly used driving energy source is the power source or fluid source. If the power source is selected as the driving energy source, the three-phase power source is generally selected for the large-size valve, and the single-phase power source is selected for the small-sized valve. General electric actuators are available in a variety of power types. Sometimes DC power can be selected. At this time, the battery can be safely operated by installing a battery. There are many types of fluid sources, which can be different media such as compressed air, nitrogen, natural gas, hydraulic fluid, etc. Secondly, they can have various pressures, and the third actuator has various sizes to provide output torque. CONTROL VALVE TYPE When selecting the actuator for the control valve, it is necessary to know the type of control valve so that the correct actuator type can be selected. Some valves require a multi-turn drive, some require a single-turn drive, and some require reciprocating drive, which affects the choice of actuator type. Generally, a multi-turn pneumatic actuator is more expensive than an electric multi-turn actuator, …

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Pneumatic control valves often present some troublesome problems during use. For example, if the pneumatic control valve is not tight and the door is not tight, what should I do? Under normal circumstances, if it is not critical, first check to see if the valve is closed. If it is closed, it is still leaky and can not be sealed. Then look at the sealing surface condition, some valve sealing pair It is detachable, so take it out for grinding and experiment again. Of course, if it is still not tight, then it is necessary to return to the factory for repair or replace the valve, so as not to affect the normal use of the valve and the occurrence of working conditions and other problems. If the valve is not tight, you should first find out where the problem is, and then deal with it according to the corresponding method. There are several reasons why the general valve is not tight: Impurities are stuck on the sealing surface, and debris is deposited at the bottom of the valve or between the valve …

The reason for and treatment of the pneumatic control valve is not tight Read More »

The working model of the pneumatic control valve is air opening and gas closing. The opening of the air opening valve increases with the increase of the signal pressure. When there is no pressure signal, the valve is in the fully open state, and the gas closing is the opposite. Reasonable selection of the mode of action of the control valve is essential to ensure production safety, improve product quality and reduce economic losses. It is also possible to achieve the function of fault retention by correct selection of the air opening and air closing modes. ADJUSTING VALVE AIR OPENING AND AIR CLOSING SELECTION The choice of the mode of operation of the control valve should be determined according to the requirements of the production process. Consider the position where the control valve is opened or closed when the signal pressure is interrupted (such as the failure of the control valve, the interruption of the meter supply or the interruption of the air supply). It depends on the degree of harm caused by the production process. If the valve is in the open position, …

How to correctly choose the positive and negative ways of the pneumatic control valve Read More »

As an important element in the flow control system, the control valve adjusts the medium flow rate of the system by changing its own resistance characteristics. Its regulating quality affects the efficiency and stability of the entire system. Design the control valve according to the regulation needs of the system. The key is to design the control valve structure and the flow area distribution of the valve core. The existing researches on the flow characteristics of the control valve are mainly concentrated on the following aspects. First, the research on the flow regulation theory, including the establishment and improvement of mathematical models and the discussion of evaluation standards. The second is to analyze the flow characteristics and improvement methods based on specific valve types using tests or engineering experience; the third is to analyze the flow characteristics using CED technology for specific valve types. For the discussion of the relationship between the flow characteristics and the flow area distribution, the literature describes the calculation of the flow area distribution of a specific type of control valve with the help of …

An Analysis Of Flow Characteristics Control Valves and Flow Optimization Computation of a Perforated Sleeve Valve Read More »

Valve products have been widely applied in petroleum, chemical engineering, nuclear power, metallurgy, electric power, hydraulic power, large coal chemical industry and other industries. Total quantity of valve products is constantly growing. Valve technology is developing and application of valve is also expanding continuously. Valve standards relative to valve products are showing their importance in at present. Valve products have been widely applied in petroleum, chemical engineering, nuclear power, metallurgy, electric power, hydraulic power, large coal chemical industry and other industries. Total quantity of valve products is constantly growing. Valve technology is developing and application of valve is also expanding continuously. Valve standards relative to valve products are showing their importance in at present. USAGE OF VALVE STANDARDS IN CHINA Using international standards and foreign advanced standards is an important standardization policy in China. Valve standards are also implementing the policy actively. For basic standards, method standards and product standards, valve standards adopt large numbers of international and foreign advanced standards, highly improving technical level of Chinese valve standards. 1. USING INTERNATIONAL STANDARDS Most of international standards have been transferred …

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A control valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller.[1] This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level. In automatic control terminology a control valve is termed a “final control element”. Contents    Operation Control action  Valve positioners Types of control valve bodies List of common types of control valve  Operation Air-actuated control valves each with a 4-20 mA “I to P” converter integral to a valve positioner. In this example each positioner is comparing the valve stem travel against control signal, and applying any correction.The opening or closing of automatic control valves is usually done by electrical, hydraulic or pneumatic actuators. Normally with a modulating valve, which can be set to any position between fully open and fully closed, valve positioners are used to ensure the valve attains the desired degree of opening. Air-actuated valves are commonly used because of their simplicity, as they only require a compressed air supply, whereas electrically-operated …

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From Wikipedia, the free encyclopedia Cavitation is the formation of vapour cavities in a liquid, small liquid-free zones (“bubbles” or “voids”), that are the consequence of forces acting upon the liquid. It usually occurs when a liquid is subjected to rapid changes of pressure that cause the formation of cavities in the liquid where the pressure is relatively low. When subjected to higher pressure, the voids implode and can generate an intense shock wave. Cavitation is a significant cause of wear in some engineering contexts. Collapsing voids that implode near to a metal surface cause cyclic stress through repeated implosion. This results in surface fatigue of the metal causing a type of wear also called “cavitation”. The most common examples of this kind of wear are to pump impellers, and bends where a sudden change in the direction of liquid occurs. Cavitation is usually divided into two classes of behavior: inertial (or transient) cavitation and non-inertial cavitation. Inertial cavitation is the process where a void or bubble in a liquid rapidly collapses, producing a shock wave. Inertial cavitation occurs in …

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