Selecting Valves for Water Supply Pipelines
(1) When the diameter of the pipeline is less than 50mm, a shut-off valve should be used. When the diameter of the pipeline is greater than 50mm, gate valves or butterfly valves should be used.
(2) When adjusting flow and water pressure, regulating valves and shut-off valves should be used.
(3) For parts with low water flow resistance, for example, the suction pipe of a water pump, gate valves should be used.
(4) Gate valves and butterfly valves should be used on pipelines that require bidirectional water flow, and globe valves should not be used.
(5) In areas with limited installation space, butterfly valves and ball valves should be used.
(6) Globe valves should be used on frequently opened and closed pipe sections.
(7) Multifunctional valves should be used on large-diameter pump outlet pipes.
Advantages and disadvantages of different valves
1. Gate valves
Advantages
The fluid resistance is small, and the required torque for opening and closing is small. It can be used on circular pipelines with bidirectional flow of media, that is, the flow direction of the media is not restricted. When a gate valve is fully opened, the corrosion of the working medium on the sealing surface is less than that of the shut-off valve. The structure is relatively simple; the manufacturing process is good, and the length of the structure is relatively short.
Disadvantages
The overall size and opening height are great, and the installation space is also big. In the opening and closing process, the sealing surface experiences relative friction and wear, which can easily cause wear even at high temperatures. Gate valves generally have two sealing surfaces, which increase the difficulty of machining, grinding, and maintenance and have long opening and closing time.
2. Butterfly valves
Advantages
Butterfly valves have features of simple structure, small sizes, light weight, quick opening and closing, low flow resistance and save consumables. According to the strength of the sealing surface, a butterfly valve can be used for both solid particle suspension media and powdery and granular media. It is also suitable for bidirectional opening and adjustment of ventilation and dust removal pipelines, which is widely used in gas and water pipelines in metallurgical, light industry, power, and petrochemical systems.
Disadvantages
The range of flow regulation is not great. When the opening reaches 30%, the flow rate enters over 95%. Butterfly valves are not suitable for use in ultra-high temperature and high pressure pipeline systems due to the limitations of the structure and sealing materials of butterfly valves. The general working temperature and pressure are below 450℃ and PN160. The sealing performance of a butterfly valve is worse than that of ball valves and globe valves, so it is used in places where requirements for sealing are not very high.
3. Globe valves
Advantages
In the opening and closing process, the friction between the valve disc and the sealing surface of the valve body is smaller than that of the gate valve, so it has wear resistance. The opening height is generally only 1/4 of the valve seat channel, so it is much smaller than a gate valve. Usually, there is only one sealing surface on the valve body and disc, so the manufacturing process is better and it is easier to maintain. Globe valves have high-temperature resistance due to the fact that fillers are generally a mixture of asbestos and graphite. Usually, globe valves are adopted for steam valves.
Disadvantages
The minimum flow resistance of the globe valve is also higher than most other types of valves due to the change in the flow direction of the medium through the valve.
(2) When adjusting flow and water pressure, regulating valves and shut-off valves should be used.
(3) For parts with low water flow resistance, for example, the suction pipe of a water pump, gate valves should be used.
(4) Gate valves and butterfly valves should be used on pipelines that require bidirectional water flow, and globe valves should not be used.
(5) In areas with limited installation space, butterfly valves and ball valves should be used.
(6) Globe valves should be used on frequently opened and closed pipe sections.
(7) Multifunctional valves should be used on large-diameter pump outlet pipes.
Advantages and disadvantages of different valves
1. Gate valves
Advantages
The fluid resistance is small, and the required torque for opening and closing is small. It can be used on circular pipelines with bidirectional flow of media, that is, the flow direction of the media is not restricted. When a gate valve is fully opened, the corrosion of the working medium on the sealing surface is less than that of the shut-off valve. The structure is relatively simple; the manufacturing process is good, and the length of the structure is relatively short.
Disadvantages
The overall size and opening height are great, and the installation space is also big. In the opening and closing process, the sealing surface experiences relative friction and wear, which can easily cause wear even at high temperatures. Gate valves generally have two sealing surfaces, which increase the difficulty of machining, grinding, and maintenance and have long opening and closing time.
2. Butterfly valves
Advantages
Butterfly valves have features of simple structure, small sizes, light weight, quick opening and closing, low flow resistance and save consumables. According to the strength of the sealing surface, a butterfly valve can be used for both solid particle suspension media and powdery and granular media. It is also suitable for bidirectional opening and adjustment of ventilation and dust removal pipelines, which is widely used in gas and water pipelines in metallurgical, light industry, power, and petrochemical systems.
Disadvantages
The range of flow regulation is not great. When the opening reaches 30%, the flow rate enters over 95%. Butterfly valves are not suitable for use in ultra-high temperature and high pressure pipeline systems due to the limitations of the structure and sealing materials of butterfly valves. The general working temperature and pressure are below 450℃ and PN160. The sealing performance of a butterfly valve is worse than that of ball valves and globe valves, so it is used in places where requirements for sealing are not very high.
3. Globe valves
Advantages
In the opening and closing process, the friction between the valve disc and the sealing surface of the valve body is smaller than that of the gate valve, so it has wear resistance. The opening height is generally only 1/4 of the valve seat channel, so it is much smaller than a gate valve. Usually, there is only one sealing surface on the valve body and disc, so the manufacturing process is better and it is easier to maintain. Globe valves have high-temperature resistance due to the fact that fillers are generally a mixture of asbestos and graphite. Usually, globe valves are adopted for steam valves.
Disadvantages
The minimum flow resistance of the globe valve is also higher than most other types of valves due to the change in the flow direction of the medium through the valve.
