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. In the forward type, the valve shaft rises when the operating signal and drive source disappear, while the reverse type decreases.
Valve body
There are more types of valve bodies than actuation equipment, and they are selected according to the type of valve, the size of the diameter and the fluid conditions. There are angle valves, three-way valves, barrier valves, gate valves, butterfly valves, ball valves, migraine rotary valves, etc.
Ball valves are the most common type. The pneumatic control signal is transmitted to the actuator, that is, the cylinder type or barrier pneumatic actuator, so that the valve stem moves up and down.
Types and characteristics of valves
Type: Features and uses
The single-seat ball valve has good control performance and small leakage when the valve is fully closed.
In addition to slurry or strong corrosive fluids, it can be widely used in water, steam, gas, etc.
Double-seat ball valve The structure of two sets of seats and plugs is used to reduce the burden on the drive equipment.
When the valve is fully closed, the leakage is large and the inter-surface scale is large, so there are certain constraints on the use.
Instrument valve The valve plug in the cylinder is modified to a movable structure
In order to prevent the valve plug from vibrating due to excessive differential pressure.
However, it is important to note that there may be fibers and waste between the cylinder and the plug.
Butterfly valve is used for the control of low differential pressure such as furnace pressure and gas combustion.
There are also high-performance butterfly valves for steam and medium-differential pressure conditions.
Ball valves are mostly used for ON/OFF operations such as pipeline switching.
Sometimes an existing manual valve is also replaced with a ball valve to complete the automated changeover.
The Bias Rotary Valve has a large capacity and can be used for slurry.
The plug is bowl-shaped, susceptible to fluid bias and has a limited range of use.
Saunders valves are suitable for corrosive fluids and slurries, but are less durable.
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