Uses of butterfly valves

Butterfly valves are generally used for larger pipe diameters, while globe valves are used for smaller ones. The pipe diameter is generally DN150~DN200. Generally speaking, the sealing performance of butterfly valves cannot compare to that of globe valves.

Here, butterfly valves are generally used for sizes above DN350, while globe valves are used for those below that size.

Butterfly valves are generally used for larger pipe diameters, while globe valves are used for smaller ones. If the pressure is high, the butterfly valve won’t work.

Butterfly valves are not very tolerant to pressure differences; it’s necessary to check what the pressure on the bus is and what the pressure behind the valve is. Generally, the disc in a butterfly valve can withstand a pressure of up to 900 lb.

What I have here are mainly DN200 and below (I think the maximum is DN300). The original design used butterfly valves; there are no other shut-off valves between the external pipelines and the circulating water main. What I’m considering now is that if there’s a problem with the heat exchanger and it needs to be shut off for repairs, whether butterfly valves would be an appropriate choice. Can a gate valve be used for the entire pipeline?

As a supplementary note, the pressure is 0.5 Mpa (gauge).

Now, the sealing level and compatibility with the medium are no longer issues; the main problem associated with butterfly valves is the magnitude of the pressure difference before and after the valve. Therefore, whether to use a butterfly valve depends on the pressure difference involved.

Has anyone come across butterfly valves that use ejector pins to control pressure?

There’s no need to consider this at all; butterfly valves are definitely an option. They require no maintenance, and if costs are a concern, then globe valves and gate valves can be used

We use ball valves for everything. There should be no leaks at the connection to the heat exchanger, as this could affect production on other lines. Disc valves are used for the valves on the main pipeline; once those are activated, the entire plant comes to a stop! The pressure can be released, so there is less leakage!

1. Structural characteristics: The center of the valve disc structure (i.e., the center of the valve shaft) is offset by a distance a with respect to the sealing surface of the valve disc; it is also offset by a distance b with respect to the center line of the valve body. Meanwhile, the center line of the valve body’s sealing surface forms an angular offset of ß with respect to the center line of the valve seat (i.e., the center line of the valve body). 2. Sealing principle: Based on the double-eccentric sealed butterfly valve, the center line of the valve seat is offset from the center line of the valve body by an angle of β ； When the triple-eccentric butterfly valve is in its fully open position, the sealing surface of the valve disc is completely separated from the sealing surface of the valve seat. A gap y, identical to that found in double-eccentric sealed butterfly valves, is formed between the sealing surface of the valve disc and that of the valve seat. As can be seen from Figure 3-101, the formation of the β angle results in the tangent to the rotation trajectory of the valve disc’s sealing surface on the large and small circles defined by the long and short radii forming an angle β with the sealing surface of the valve seat. Angles θ1 and θ2 enable the valve disc, during opening and closing, to gradually disengage and then gradually press against the sealing surface of the valve seat, thereby completely eliminating mechanical wear and scuffing between the two sealing surfaces of the butterfly valve’s sealing pair when the valve disc is opened and closed. When such valves are opened from 0-90°, the sealing surface of the valve disc separates from the sealing surface of the valve seat in an instant; whereas when they are closed from 90° to 0°, it is only at the moment of closure that the sealing surface of the valve disc comes into contact with and presses against the sealing surface of the valve seat. Due to the formation of the angles θ1 and θ2, when the butterfly valve is closed, the sealing pressure between the two sealing surfaces of the sealing pair can be generated by the driving torque applied to the valve shaft rather than by the elasticity of the valve seat as in conventional butterfly valves. This approach eliminates the reduction or disappearance of the sealing pressure between the two sealing surfaces, which in conventional butterfly valves is caused by factors such as the aging of the elastic material in the valve seat, cold flow, and loss of elasticity. Furthermore, by adjusting the applied driving torque, its sealing pressure ratio can be modified as desired, thereby significantly improving the sealing performance and service life of the triple-eccentric butterfly valve. 1. The main reasons for the failure of the sealing pair’s sealing performance. The medium affects cavitation and erosion on the two sealing surfaces of the sealing pair. 2. Characteristics of the triple-eccentric butterfly valve: The sealing pair has a complex design, is difficult to manufacture, and results in high costs; it offers excellent sealing performance, a particularly long service life, and can operate at high pressures. During the study*, everyone is welcome to discuss together! MSN:haha-energy@hotmail.com

Butterfly valves are suitable for applications with large pipe diameters and low pressures; for other cases, globe valves are better to use.