The difference between gate valve and knife gate valve
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In some special cases, knife gate valves are selected for large diameter pipelines instead of ordinary gate valves. What's the difference between the two? Working principle, performance, price?
Knife gate valves are also very capable in media with consistency and solid particles. The face-to-face installation size is small and easy to install. The full-bore knife gate valve design allows the valve to be used in dirty media. The replaceable valve seat and packing make the valve maintenance simple.
There are one-way seals and two-way seals. Valve seat: There are metal seals or soft seals.
Just to add: The medium is the return air from the filter. When DN250 is used, a gate valve is used, and when DN450 is used, a knife-type gate valve is used. In addition to installation size, what other reasons are there? I asked about the price and it was said that it was 20% higher. I don’t know the accuracy of this data.
The sealing material is EPDM (ethylene propylene diene rubber) NBR (butadiene rubber) Viton (Vito) White Silicone (white silicone) PTFE (polytetrafluoroethylene) Packing material Dynapack (graphite oil-impregnated PTFE & aramid yarn braided elastomer core) / (DP) fiber braided oil-impregnated PTFE / ST braided PTFE / TH graphite / GR ceramic fiber / FC The transmission is manual: handwheel lifting and lever lifting. Pneumatic actuator double-acting: aluminum electric actuator pneumatic actuator single-acting air loss safety system commonly used pressure is 50-1200, but the larger the pressure, the smaller the pressure. The pressure usually used is about 10 kg. Extension rod operating mechanism
Knife gate valve has simple structure, small size, only wafer type, and flexible operation.
Since it has such advantages and does not replace the use of ordinary gate valves, what is the main reason? Or is it the price factor?
Knife gate valves do not have high pressure resistance, and their prices are much higher than ordinary gate valves!
Generally, knife gate valves are used for fluids with particles. Knife gate valves are more expensive. Our company's acetylene slag discharge valve uses the Xihu knife gate valve, which is quite expensive.
Dare I ask, how is it more expensive than ordinary gate valves? The people in our purchasing department here asked a few questions and couldn't explain the estimated budget, but they didn't even know this concept.……