Pneumatic sleeve type regulating valve

There are two main types of straight stroke: straight single seat and straight double seat. The latter has the characteristics of high flow capacity, low imbalance force, and stable operation, so it is usually particularly suitable for situations with high flow rate, high pressure drop, and few leaks. The angular stroke mainly includes V-shaped electric regulating ball valve, pneumatic diaphragm cut-off valve, eccentric butterfly valve, etc.

The application of flow control valves in the pipeline network can directly set the flow rate according to the design. The valve can automatically eliminate the residual pressure head and flow deviation caused by pressure fluctuations in the pipeline under the action of water, and maintain the set flow rate regardless of changes in system pressure. These functions of the valve enable the flow regulation of the pipeline network to be completed in one go, transforming the network adjustment work into simple flow distribution and effectively solving the hydraulic imbalance of the pipeline network. The flow control valve is mainly used in centralized heating (cooling) and other water systems to distribute the flow of the pipeline network as needed, eliminate hydraulic imbalance in the water system, solve the problem of uneven heating and cooling, and save energy by 15% -20%.

Technical parameters:

1、 The characteristics of small flow control valves

The so-called small flow regulating valve, as the name suggests, is a regulating valve with very low flow capacity.

The flow capacity of a valve is a valve capacity indicator under unified conditions. In our country, it is represented by the value of C. Its definition is: when the valve is fully open, when the pressure difference before and after the valve is 1 kilogram/cm2, and the medium weight is 1 gram/cm3, the medium mass flowing through the valve per hour (m3/hour). For incompressible fluids, in a sufficiently turbulent state (when the Reynolds number is large enough, for water Re>10 5; for air Re>5.5 × 10 4)

In the formula:

△ p - Pressure difference before and after valve (kg/cm2) Υ-- Medium weight (g/cm3)

Q - Medium flow rate (m3/hour)

The United States and other countries use C, where the value represents the flow capacity of the valve. The internationally recognized I, E, and C standards for electricity mainly use Av values to represent the flow capacity of valves. The conversion relationship between the three is as follows:

C=1.17 C Cv=10 6/24Av C=10 6/28Av

The flow capacity of a valve only depends on the structure of the valve itself. When calculating the required valve flow capacity, attention should be paid to the significant differences in the flow state inside the valve due to different media or flow conditions.

In low flow conditions, especially when working with viscous fluids and low pressure, the main constraint of the fluid is often laminar or a mixture of laminar and turbulent flow. When laminar flow occurs, there is a linear relationship between the flow rate of the medium passing through the valve and the pressure difference before and after the valve. In laminar and turbulent mixed states, as the Reynolds number increases, even if the pressure difference remains constant, the mass of the medium flowing through the valve will also increase. In complete turbulence, the flow rate does not change with the change of Reynolds number. Nevertheless, choosing a small flow control valve still relies on traditional methods

The method and calculation formula are used. However, its calculated value deviates greatly from the actual value. According to the data, when Cv=O.01 or below, it is only used as a capacity indicator and has reference significance. The actual circulation capacity should be determined based on experience.

As the flow capacity decreases, the adjustable ratio of the valve will decrease. But at least it can guarantee a flow rate between 10:1 and 15:1. If the adjustable ratio is too small, it will be difficult to adjust the flow rate.

When valves are used in series, as the opening changes, the pressure difference before and after the valve also changes, which causes the working characteristic curve of the valve to deviate from the ideal characteristics. If the pipeline resistance is high, the linearity will become a fast opening characteristic and lose the ability to adjust. The equal percentage characteristic will become a straight line characteristic. Under low flow conditions, due to minimal pipeline resistance, the distortion of the above characteristics is not significant, and the equivalent percentage characteristic is actually unnecessary. From a manufacturing perspective, it is also impossible to generate an equal percentage of side shape below Cv=O.05. Therefore, the main problem with small flow valves is how to control the flow within the required range.

From an economic perspective, users hope that a valve can be used for both interception and regulation simultaneously. But for regulating valves, the main purpose is to control the flow rate, and closing is secondary.

Introduction to Features:

The pneumatic diaphragm single seat regulating valve has a valve core and a valve seat inside the valve body, which has the characteristic of small leakage. This valve has a large unbalanced force and allows for a smaller pressure difference compared to a double seat valve. When operating under high pressure and with a large diameter, it is best to equip it with a valve positioner. Valves with a nominal diameter of ≥ 25mm have a dual guide structure. As long as the connection position between the valve stem and the valve core of the pneumatic diaphragm single seat regulating valve is changed, it can achieve pneumatic opening or closing.

A single seat pneumatic diaphragm single seat regulating valve has a valve core and a valve seat inside the valve body. As long as the connection position between the valve stem and the valve core is changed, air opening or air closing can be achieved.

Main features: Equipped with PSL intelligent straight stroke electric actuator, it has a small volume, complete specifications, light weight, high thrust, convenient operation, no adjustable potentiometer, reliable single seat regulating valve (10 pieces), high pressure, and low noise. The PSL electric actuator adopts a modular design with self diagnostic function, making it very convenient to use and adjust.

There is a digital display window where you can see the control signal value and valve position value.

PSL intelligent electric actuator function: fault diagnosis, alarm and protection function with broken control signal. When the signal is disconnected, the actuator can be turned on or off; Or close; Or maintain; Or set at any position between 0 and 100%. And with valve blockage fault diagnosis, alarm and protection functions.

The TP series adopts a top guided, pneumatic thin film single seat regulating valve single seat sealing structure. Compared with other similar regulating valves, it has outstanding advantages such as simple structure, large rated flow coefficient, and small valve seat leakage. In addition, the TP series with a soft sealing structure has both regulating and cut-off functions, making it a regulating and cut-off type regulating valve that can also be used as a cut-off valve.