Product Details

Product overview
Pneumatic diaphragm control valve is the execution unit of the automatic control system in the industrial production process, which changes the opening degree of the valve according to the signal of the regulating instrument, so as to achieve the adjustment of parameters such as pressure, temperature, flow and liquid level.

Pneumatic diaphragm regulating valve has the advantages of small size, simple structure, easy to use, fireproof, explosion-proof and convenient maintenance, so it is widely used in automatic adjustment and remote control system of industrial production processes such as chemical, petroleum, metallurgy, electric power, light industry and so on.

Construction and working principle
1. Structure: Pneumatic membrane diaphragm regulating valve is composed of two parts: pneumatic membrane actuator and regulating valve. The new series of pneumatic actuators adopts a multi-spring structure. Therefore, the height of the actuator is greatly reduced, the weight is also reduced accordingly, and the valve body part of the regulating valve is a low-flow resistance valve body designed according to the principle of hydrodynamics, and the rated flow coefficient is increased by about 30%. The pneumatic membrane control valve has two modes of air opening and air closing. The choice of air opening and closing is mainly based on the safety of production, considering that when the input signal is interrupted, the valve is in a safe switching state for the system.

2. Working principle: the action of the pneumatic membrane diaphragm regulating valve is generated by the signal pressure of the regulator, and the thrust is generated in the air chamber of the pneumatic membrane actuator, and the valve core is pushed by the connecting rod, and the corresponding displacement is generated one by one, that is, the so-called stroke, and the change of the valve core position changes the circulation cross-sectional area of the valve, so as to achieve the purpose of adjusting the medium flow.

Dimensions

Note: 1. The flange connection dimensions of this product are PN16 and PN25 according to JB79.1-94 standard, PN64 is according to JB79.2-94 standard, and the structure length is according to GB2221-89 standard.

2. The flange sealing form of this product has two types: convex and concave, which can be specified by the user, and when the user is not specified, PN16 is pressed convex, PN40, PN64 is concave.

Product technical parameters

Key performance indicators

Installation and maintenance

1. The installation position of the pneumatic diaphragm diaphragm regulating valve (hereinafter referred to as the valve) should have an appropriate height from the ground, and there is a certain space above and below the valve to facilitate the disassembly, transportation and repair of the valve. For valves equipped with pneumatic valve positioners and handwheel mechanisms, the safety and convenience of observation, adjustment and operation should be ensured.
2. Avoid bringing additional stress to the valve due to careless installation, such as the pipe and the valve are not centered or the flange surface is not parallel, the combined effect of the self-weight of the valve, the surrounding vibration, the change of medium temperature and ambient temperature will make the flange rupture or deformation. In order to avoid such accidents, the valve is installed on a section of elbow such as (fig. 6), and large diameters should be supported.
3. The working environment temperature of the valve should be -30~+60 °C, and the relative temperature should not be more than 95%. Because parts like rubber products such as corrugated films and seals harden and become brittle at low temperatures, aging accelerates at high temperatures. Pay attention to this point when the valve position is close to the heating furnace and the high-temperature pipeline.
4. The valve is installed vertically upright, and can also be installed inclined and inverted. When installed at an angle, the valve core and bushing are offset due to its own weight; The spool and seat accelerate local wear. The disadvantage of inverted installation is that the medium leaking from the packing is stained or corrodes the pneumatic membrane actuator.
5. Pipeline. The piping (fig 6) is set up to facilitate non-stop access to the valve after switching or manual operation.
Due to the adjustment of low pressure, normal temperature, non-corrosive medium (such as water, air, etc.) valve will not occur corrosion, wear, jamming accident, or because of the valve nominal diameter is large (DN100 mm or more), the installation of the pipe price is high, when the area is large, the pipe can be omitted, but the valve should be equipped with a handwheel mechanism, so that the automatic control system can be operated manually when it fails.
6. Air pipeline. The air pipeline is a copper pipe or plastic pipe with outer diameter ×inner diameter = Ф6×Ф4 and Ф8×Ф6, and pay attention to the connection to ensure air tightness.
7. When the valve is installed on the pipeline, the direction of the arrow on the valve body is the same as the direction of the fluid in the pipeline. If the nominal diameter of the valve is different from the nominal diameter of the pipeline, a gradual shrinkage pipe is added between the two.
8. Before the valve is installed, thoroughly clean the dirt and welding slag in the pipeline. After installation, test operation was carried out with room temperature water. During the trial operation, the shut-off valve is carried out with a pong-through pipeline. If there is no piping, keep the valve in the fully open position. The tightness of cleaning pipelines and test connections during trial operation. After trial operation, the valve body is put into operation.
9. The regulating valve should ensure that the surrounding temperature is -5~+40 °C and the relative temperature is not more than 90% indoors, and the air should not contain harmful impurities that can corrode the valve, and attention should be paid to dustproof.