Do you know what to pay attention to when purchasing bare shaft butterfly valve

In the butterfly valve procurement process, there are usually two choices, butterfly valve with actuator and without actuator, if the butterfly valve an actuator, the customer does not need to worry about anything, we will debug the butterfly valve and actuator, and then sent to the customer. However, if the customer needs to replace the old valve, or has its own actuator based on the purchase of butterfly valves, you need to pay attention to the following points to ensure that the valve and the actuator can be completely matched.

1. Shaft head size - shaft head size includes shaft height (H) and shaft diameter (φd2), shaft shape, usually we have two kinds of shaft head, square shaft head and round shaft head.

2. Top flange Size - The top flange size is also a very important factor in determining whether the actuator can be installed on, usually the upper flange size is determined by the following factors, d1 and d2 There are also the number of holes in the upper flange n and hole spacing d, in order to facilitate communication, the industry will be summarized as a parameter F, if there are no special requirements, ZFA Valve according to the diameter of the valve to choose the parameters of the top flange If there is no special requirement, ZFA Valve selects the parameter F of upper flange according to the valve diameter.

3. Key number n and key width k

4. Valve torque

Valve torque is the opening torque of the valve (valve du door zhi torque) unit: Newton. Meter. The choice of valve drive capacity device is the most important parameter. The size of the opening torque is also a measure of the quality of the valve and is another important indicator of product quality, people in the evaluation of the quality of the valve, are often used to open the lightweight, flexible to describe it.

The opening torque is also known as the operating torque, the maximum value of which is in the final moment of closure or opening the initial moment. Design and manufacture of valves should strive to reduce the opening and closing forces and opening and closing moments. The opening torque can be calculated or measured to obtain approximate results, and can also be obtained by using the torque plate hand measurement.

The characteristic curve of the operating torque of the butterfly valve is high in the middle and low at both ends. The reason for this phenomenon is that, when the butterfly valve is in the middle position, the fluid is hindered by the butterfly plate and flows around the butterfly plate, forming a swirling flow on both sides of the butterfly plate and forming a flowing torque on the butterfly plate, which forces the butterfly plate to close. With the opening or closing of the butterfly plate, the fluid on both sides of the butterfly plate caused by the influence of the whirlpool is more and smaller, until the whirlpool disappears, then the butterfly plate by the resistance is also more and smaller, so the formation of the middle of the high, the two ends of the low characteristic curve. As for the operating torque in the process of opening the valve is larger than that in the process of closing, the reason is that the dynamic water torque caused by the fluid to the butterfly plate is always in the direction of closing the valve.

When the butterfly valve is configured with an actuator, it must be ensured that the output torque of the actuator is greater than the maximum torque of the butterfly valve opening, so as to ensure that the butterfly valve can be opened smoothly.

For ZFA Valve centerline butterfly valve products, the commonly used torque parameters are as follows: