Butterfly valves and gate valves in different conditions of application

Butterfly valves and gate valves in different conditions of application

Butterfly valves and gate valves are used in pipelines to switch and regulate the flow. Of course, in the butterfly valve and gate valve selection process or method.

In order to reduce the depth of pipeline overburden in the water supply network, the general caliber of the larger pipeline selection of butterfly valves, the depth of the overburden does not have much impact, and strive to select the gate valve, but the same specifications of the gate valve price than the butterfly valve prices are high. As for the caliber of the dividing line should be considered according to the specific circumstances of each place. From the use of the last decade, the butterfly valve failure than the gate valve high, so the conditions permit, expand the use of the gate valve is worthy of attention.

On the gate valve in recent years, many domestic valve manufacturers, development, imitation soft seal gate valve, this gate valve than the traditional wedge-type or parallel double gate type gate valve has the following characteristics:

Soft sealing gate valve body, valve cover using precision casting method casting, one-time molding, basic non-mechanical processing, do not use sealing copper ring, saving non-ferrous metals.

Soft seal gate valve bottom without pits, no accumulation of slag, gate valve opening and closing of the failure rate is low.

Soft seal rubber lined valve plate size unity, interchangeability.

Therefore, the soft seal gate valve will be a form of water supply industry is happy to use. At present, the domestic manufacture of soft seal gate valve caliber up to 1500mm, but most manufacturers manufacture caliber between 80-300mm, the domestic manufacturing process there are still many problems. Soft sealing gate valve key components are rubber-lined valve plate, and rubber-lined valve plate of the higher technical requirements, not all manufacturers abroad can achieve, often purchased from a reliable quality factory assembly.

　　Domestic soft seal gate valve copper nut block is embedded in the rubber lining valve plate above, similar to the structure of the gate valve, due to friction of the activities of the nut block is easy to make the lining of the valve plate peeled off. A foreign company's soft seal gate valve, copper nut block is embedded in the rubber-lined gate, forming a whole, to overcome the above shortcomings, but the valve cover and valve body combination of concentricity requirements are higher.

However, when opening and closing the soft seal gate valve, should not be closed too dead, as long as the effect of water can be achieved, otherwise it is not easy to open or rubber lining stripped. A valve manufacturer, in the valve pressure test, the use of torque plate hand to control the degree of closure, as the water company's valve operators should follow this method of opening and closing.

Butterfly valve in the use of gate valves where the difference?

In accordance with the role of the gate valve and butterfly valve and the use of the valve, the gate valve flow resistance is small, good sealing performance, because the gate valve valve plate and the media flow is a vertical angle, if the gate valve in the valve plate switch is not in place, the media on the valve plate scouring so that the valve plate trembling, it is very easy to shine into the seal of the gate valve damage.

Butterfly valve, also known as the flap valve, is a simple structure of the regulating valve, can be used for low-pressure pipeline media switching control of the butterfly valve refers to the closing member (valve flap or butterfly plate) for the disc, rotating around the valve axis to achieve the opening and closing of a kind of valve, the valve can be used to control the flow of various types of fluids, such as air, water, steam, a variety of corrosive mediums, slurries, oils, liquid metals and radioactive media. Mainly in the pipeline to cut off and throttling effect. Butterfly valve opening and closing parts is a disc-shaped butterfly plate, in the valve body around its own axis rotation, so as to achieve the purpose of opening and closing or regulation.

Butterfly driven by the valve stem, if turned 90 °, will be able to complete an opening and closing. Change the deflection angle of the butterfly plate, you can control the flow of the medium.

Use of 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 pipeline, used to regulate and cut off the flow of media.

Gate valve (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, the gate valve can only be used for the full open and full closed, does not apply to the parameters of the gate, usually 5 °, the media temperature is not high for the 2 ° 52'. Improve its craftsmanship, make up for the angle of the sealing surface in the processing of the deviation, this gate is called resilient gate.

Gate valve closed, the sealing surface can only rely on media pressure to seal, that is, only rely on media pressure to the sealing surface of the gate to the other side of the valve seat to ensure that the sealing surface sealing, this is the self-sealing. Most of the gate valve is used to force sealing, that is, when the valve is closed, to rely on external forces to force the gate to the valve seat to ensure that the sealing surface of the sealing.

Motion: The gate of the gate valve with the valve stem for linear motion, also known as open stem gate valve. Usually there are trapezoidal threads on the lifting rod, through the nut at the top of the valve and the guide groove on the valve body, the rotary motion into a straight line motion, that is, the operating torque into the operating thrust. When the valve is opened, the passage of the fluid is completely free when the height of the gate lift is equal to 1:1 times the diameter of the valve, but this position cannot be monitored during operation. In actual use, it is the apex of the valve stem as a mark, i.e., the position of opening motionless, as its fully open position. In order to take into account the temperature changes in the phenomenon of locking, usually open to the apex of the position, and then back 1/2-1 turn, as the fully open position of the valve. Therefore, the valve's fully open position, according to the position of the gate (i.e., trip〉 to determine. Some gate valve stem nut is located in the gate, the handwheel rotation drives the valve stem rotation, so that the gate lift, this valve is called a rotating rod gate valve or called the dark rod gate valve.