Comparison of Gate Valves and Butterfly Valves

Both gate and butterfly valves play an important role in switching and regulating flow in piping systems. However, certain methods and strategies do exist when selecting and configuring these two types of valves.
In the water supply network, butterfly valves are usually chosen for large-diameter pipelines in order to minimize the depth of overburden of the pipeline. For cases where the depth of overburden has little effect, gate valves are preferred. However, it is worth noting that the price of gate valves with the same specifications is usually higher than that of butterfly valves. As for the specific caliber dividing line, it may vary from place to place according to the actual situation. From the experience of the past decade, butterfly valves have a relatively high failure rate, so it has become a noteworthy trend to expand the use of gate valves where conditions permit.
In recent years, many domestic valve manufacturers have begun to develop and imitate soft seal gate valves. This kind of gate valve has the following characteristics compared with the traditional wedge-type or parallel double-gate gate valve: the valve body and the valve cover are molded at one time by the precision casting method, which does not require machining or the use of sealing copper rings, thus saving non-ferrous metals. In addition, there is no pit at the bottom of the soft seal gate valve, which will not accumulate slag, so the failure rate of opening and closing the gate valve is low. At the same time, the soft seal liner valve plate has a uniform size and is highly interchangeable. Therefore, the soft seal gate valve has become a favored choice in the water supply industry. At present, the domestic manufacture of soft seal gate valve caliber up to 1500mm, but most manufacturers manufacture caliber between 80-300mm. In the manufacturing process, there are still some problems in China. In particular, the key component of the soft sealing gate valve – rubber lined valve plate has high technical requirements, not all manufacturers can meet this standard, often need to be purchased from reliable quality manufacturers for assembly.
In the use of soft seal gate valve, it should be noted that the opening and closing should not be closed too tight, as long as the water stopping effect can be achieved, otherwise it may lead to not easy to open or rubber lining stripping. Some valve manufacturers use torque wrenches to control the degree of closure during valve pressure testing and inspection. As a valve operator, you can also learn from this method of opening and closing.
So, what is the difference between butterfly valves and gate valves in terms of specific use?
Gate valves are characterized by small flow resistance and good sealing performance. As the valve plate of the gate valve and the media flow at a perpendicular angle, if the valve plate is not switched on and off, the flushing of the media on the valve plate may cause the valve plate to flutter, which in turn damages the sealing of the gate valve. And butterfly valve, also known as flap valve, is a simple structure of the regulating valve. The closing member (valve flap or butterfly plate) of a butterfly valve is a disk that rotates around the valve shaft to achieve opening and closing. Butterfly valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, slurry, oil, liquid metals and radioactive media. In the pipeline, butterfly valve mainly plays the role of cutting off and throttling. The opening and closing member of butterfly valve is a disc-shaped butterfly plate, which rotates around its own axis in the valve body, so as to achieve the purpose of opening and closing or regulating. By changing the deflection angle of the butterfly plate, the flow rate of the medium can be controlled.
In terms of application conditions and media, butterfly valve is suitable for furnace, gas, natural gas, liquefied petroleum gas, city gas, hot and cold air, chemical smelting and power generation and environmental protection, building water supply and drainage and other engineering systems to transport a variety of corrosive, non-corrosive fluid media on the pipeline. The gate valve is an opening and closing member of the gate, the movement direction of the gate is perpendicular to the direction of the fluid. Gate valve usually only full open and full closed, can not be used to regulate the flow. The sealing performance of gate valves can be adjusted according to media parameters and temperature. Most gate valves use forced sealing, i.e., the valve needs to rely on external force to press the gate to the valve seat to ensure sealing when the valve is closed. However, there are also some gate valves with self-sealing method, that is, rely on the medium pressure to press the sealing surface of the gate plate to the other side of the valve seat to ensure the sealing.
In the movement mode, the gate of the gate valve along with the valve stem for linear movement, this valve is also known as open stem gate valve. While some gate valves have a stem nut located on the gate plate, the rotation of the handwheel drives the stem to rotate, thus lifting the gate plate, and this kind of valve is known as a rotating stem gate valve or a dark stem gate valve.
We hope this information can help you better understand and choose gate valves and butterfly valves.