the difference between gate valve and butterfly valve

Butterfly valve is one kind of industrial valves which uses a circular disc as an opening and closing part(usually we called it valve disc or valve plate), that disc rotates with the valve stem to open,close and adjust the fluid channel. 

Gate valve is one kind of industrial valve whose disc moves perpendicular to the direction of the fluid. The gate valve can only be fully opened and fully closed, and cannot be used to adjust or throttle. The gate valve is sealed by the connect between the valve seat and the valve plate. Usually the sealing surface will be welded with metal materials to increase wear resistance, such as 1Cr13, STL6, stainless steel,etc. The valve plate has rigid plate and resilient plate, according to the different valve plate, gate valve can be divided into rigid gate valve and resilient gate valve. 

today we are going to list four kind of difference between gate valve and butterfly valve:

The difference of gate valve and butterfly valve in structure: 

Butterfly valve is mainly composed of valve body, butterfly plate, valve stem, sealing ring and transmission device. 

1. valve body: the valve body of butterfly valve is cylindrical, the upper and lower parts each have a cylindrical boss for installing the valve stem. Butterfly valves and pipelines are mostly connected by flanges; if butterfly valves are connected with pipelines in wafer type, its face to face length is the smallest. 

2. Valve stem: the valve stem is the rotating shaft of the butterfly plate, and the shaft end adopts the packing box sealing structure, which can prevent the leakage of the medium. The upper end of the valve stem is directly connected with the transmission device to transmit torque. 

3. Butterfly plate: butterfly plate is the opening and closing part of the butterfly valves. 

The gate valve is generally composed of valve body, valve seat, valve stem, valve disc, bonnet, and sealing ring,etc. By changing the transmission device and the configuration of the gate valve, a variety of electric gate valves and pneumatic gate valves can be transformed. 

Difference of gate valve and butterfly valve in flow characteristic curves: 

Gate valve: gate valve has small resistance, and good shut-off, good airtightness after closing, less internal leakage, but gate valve is not conducive for flow regulation, gate valve is usually used for shut-off in the main pipelines. 

Butterfly valve: butterfly valve has small size, and is combined with the advantages of globe valve and ball valve. The shape of the valve disc can be adjusted to design valves with different flow characteristics, and it has good shut off performance. Butterfly valve can be design into large diameter ones, and can have wide range of applications. Butterfly valves can be used for cold water and hot water. 

Difference of gate valve and butterfly valve in applications: 

Gate valve is one of the commonly used shut-off valves, it is mainly used to connect or cut off the medium in the pipeline, and is not suitable for regulating the flow of the medium. Butterfly valve is suitable for a wide range of pressure, temperature and diameter, especially for medium and large diameter pipelines. 

Butterfly valve is suitable for pipelines conveying various corrosive and non corrosive fluid medium in engineering systems such as producer, coal gas, natural gas, liquefied petroleum gas, city gas, hot and cold air, chemical smelting and power generation environmental protection, building water supply and drainage,etc. The characteristics of the industrial butterfly valve are high temperature resistance, high applicable pressure range, large nominal diameter of the valve, valve body of butterfly valve is made of carbon steel, the sealing ring of valve disc is using the metal ring instead of rubber ring, large high temperature butterfly valve is welded with steel plates, which is mainly used flue air duct and gas pipelines of high temperature mediums. 

Generally speaking, in order to reduce the soil covering depth of the pipeline in the water supply network, butterfly valves are generally selected for pipes with large diameters. For those with little influence on the soil covering depth, gate valve should be selected, but the price of gate valves of the same specification is higher than that of butterfly valves. 

As for the demarcation line of caliber, it should be considered on case-by-case basis. For the perspective of use in the past ten years, the failure rate of butterfly valves is higher than that of gate valves, so it is worthy of attention to expand the scope of use of gate valves when conditions permit. 

The difference of gate valve and butterfly valve in installation and maintenance: 

Installation and maintenance of gate valve: 

1. the hand whee, lever handle and transmission mechanism are not allowed to be used for lifting, and collision is strictly prohibited. 
2. The double disc gate valve should be installed vertically, that is, the valve stem is in the vertical position, and the hand wheel is on the top; 
3. For gate valve with bypass valve, the bypass valve should be opened first, to balance the pressure difference between the inlet and outlet and reduce the opening force. 
4. For gate valve with transmission mechanism, it should be installed according to the provisions of the product instruction manual; 
5. If the gate valve is used frequently, lubricate it at least once a month. 

Installation and maintenance of butterfly valve: 

1. when installation, the disc of the butterfly valve should be in the closed state; 
2. The opening position should be determined according to the rotation angle of the butterfly plate; 
3. For butterfly valve with bypass valve, open the bypass valve before opening the butterfly valve; 
4. Butterfly valve should be installed according to the manufacturer’s installation instructions. For butterfly valves with heavy weight, a firm foundation should be set;