German VAPO valves VAPO models VAPO prices

VAPO valves are used in the field of industrial automation process control. They are the final control elements that change process parameters such as medium flow, pressure, temperature, and liquid level by accepting control signals output from the regulation control unit and using power operation. They generally consist of an actuator and a valve body. According to stroke characteristics, control valves can be divided into linear stroke and angular stroke; according to the power source used by the associated actuator, they can be divided into three types: pneumatic control valves, electric control valves, and hydraulic control valves; according to their functions and characteristics, they are divided into three types: linear characteristic, equal percentage characteristic, and parabolic characteristic. Control valves are suitable for media such as air, water, steam, various corrosive media, slurry, and oil products.

VAPO valve working principle

Control valves are used to regulate the flow, pressure, and liquid level of the medium. Based on the signal from the control point, the valve opening is automatically controlled to achieve regulation of the medium's flow, pressure, and liquid level. Control valves are divided into electric control valves, pneumatic control valves, and hydraulic control valves. A control valve consists of two parts: an electric or pneumatic actuator and the control valve itself. Control valves are usually divided into two types: straight-through single-seat control valves and straight-through double-seat control valves. The latter has the characteristics of large flow capacity, small unbalanced force, and stable operation, so it is particularly suitable for occasions with large flow rates, high pressure drops, and low leakage.

VAPO valve structure

Valve body types: There are many types of valve bodies for control valves. Commonly used valve body types include straight-through single-seat, straight-through double-seat, angle type, diaphragm type, small flow type, three-way, eccentric rotary, butterfly, sleeve type, and spherical. For specific selection, the following considerations can be made: 1) Valve core shape structure Mainly considered based on the selected flow characteristics and unbalanced forces. 2) Wear resistance When the fluid medium is a suspension containing high concentrations of abrasive particles, the internal materials of the valve must be hard. 3) Corrosion resistance Since the medium is corrosive, choose valves with simple structures whenever possible. 4) Medium temperature and pressure When the temperature and pressure of the medium are high and vary significantly, select valves whose valve core and seat materials are less affected by temperature and pressure changes. When the temperature is ≥250℃, a radiator should be added. 5) Prevention of flashing and cavitation Flashing and cavitation only occur in liquid media. In actual production processes, flashing and cavitation cause vibration and noise, shortening the service life of the valve. Therefore, flashing and cavitation should be prevented when selecting valves. Control valve actuators: To ensure the normal operation of the control valve, the associated actuator must generate sufficient output force to ensure tight sealing and valve opening. For double-acting pneumatic, hydraulic, and electric actuators, there is generally no return spring. The magnitude of the force is independent of its direction of motion. Therefore, the key to selecting an actuator lies in determining the maximum output force and the motor's rotational torque. For single-acting pneumatic actuators, the output force is related to the valve opening, and the forces appearing on the control valve will also affect the motion characteristics. Therefore, force balance must be established across the entire opening range of the control valve. After determining the actuator output force, select the corresponding actuator based on the requirements of the process environment. For sites with explosion-proof requirements, pneumatic actuators should be selected. From an energy-saving perspective, electric actuators should be selected whenever possible. If high regulation precision is required, hydraulic actuators can be chosen, such as for speed regulation of transparent machines in power plants or temperature regulation control of catalytic reactor units in refineries. The action mode of the control valve applies only when selecting pneumatic actuators. The action mode is formed by combining the direct/reverse action of the actuator with the direct/reverse action of the valve. There are 4 combinations: direct-direct (air-to-close), direct-reverse (air-to-open), reverse-direct (air-to-open), and reverse-reverse (air-to-close). These four combinations result in two action modes for the control valve: air-to-open and air-to-close. The selection of the control valve action mode is mainly considered from three aspects: a) process production safety; b) characteristics of the medium; c) ensuring product quality and minimizing economic losses.

VAPO valve classification

Control valves can be divided by stroke characteristics into: linear stroke and angular stroke. Linear stroke includes: single-seat valves, double-seat valves, sleeve valves, cage valves, angle valves, three-way valves, and diaphragm valves; angular stroke includes: butterfly valves, ball valves, eccentric rotary valves, and full-function ultra-light control valves. Control valves can be divided by drive method into: manual control valves, pneumatic control valves, electric control valves, and hydraulic control valves. This refers to pneumatic control valves powered by compressed air, electric control valves powered by electricity, and hydraulic control valves powered by the pressure of liquid media (such as oil). By regulation form, they can be divided into: regulating type, shut-off type, and regulating/shut-off type. By flow characteristics, they can be divided into: linear, logarithmic (percentage), parabolic, and quick-opening.

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