The Difference and Selection between Full Bore Ball Valves and Reduced Bore Ball Valves
The
ball valve is currently the most widely used mechanical product in all valve markets. It mainly consists of a valve body, valve seat, ball, valve stem, and transmission device. The actuator drives the ball core to rotate, achieving the function of switching or adjusting. It is widely used and very popular in industries such as chemical, environmental protection, water treatment, urban construction, machinery and food.
There are various types of
ball valves, which can be combined into products with different functions through different structural forms, connection methods, pressure levels, driving forms, etc. However, at the most basic level, there are two main types of ball valves: full bore ball valves and reduced bore ball valves. Generally speaking, when the inner diameter of the valve ball is less than or equal to 85% of the inner diameter of the ball valve port, it is called a reduced bore ball valve. While when the inner diameter of the ball valve is greater than 95% of the inner diameter of the ball valve port, it is called a full bore ball valve. Then, what are the differences between them in terms of selection or application?
1. Definition
A full bore ball valve has an equal width flow channel, which means that the size of the hole from the inlet to the outlet is the same. Its size cannot be less than the standard specified value, which is roughly equivalent to the nominal diameter of the specification. For example, the flow channel diameter of a DN50 full bore ball valve also needs to be around 50.
2. The inlet of the channel of reduced bore ball valves is wider than the channel diameter. The actual diameter of the channel is about one specification smaller than this specification. For example, when a DN50 reduced bore ball valve flows to a diameter of about 38, it is roughly equivalent to the specification of DN40. Shrink one specification within DN250 and two specifications between 250 to 600, depending on the actual situation for sizes above 600.
3. Applicable media:
A. Full bore ball valves are generally used for conveying viscous and easily slagging media in pipelines. Due to their low fluid resistance, they can be said to have almost no flow resistance, making it convenient for regular wax scraping and blowing devices to pass through.
B. Reduced bore ball valves are suitable for pipelines that transport gases or media with physical properties similar to water, as their weight is about 30% lighter than that of full bore ball valves, and their flow resistance is only about 1/7 of that of globe valves with the same diameter. It is beneficial for reducing pipeline load and lowering costs.
C. Applicable process:
1). For pipelines that require regular cleaning, regardless of the medium being transported, full bore ball valves must be used. The medium passing through a full bore ball valve will not reduce the flow rate, and the small flow resistance is an ideal product for pipeline control, especially in strict working conditions. Especially when the main pipelines in oil and gas pipelines need to be buried underground, full bore welded ball valves must be used.
2). Reduced bore ball valves are suitable for working conditions with low requirements and low flow resistance requirements. When the inner diameter of the valve is greater than 80% of the inner diameter of the pipe end, it has almost no effect on the fluid flow capacity of the pipeline. Many valves have a reduced diameter, generally controlled within 0.8. On the one hand, reducing the valve's flow capacity, i.e. the KV value of the valve, increases the pressure drop at both ends of the valve, causing energy loss. For pipelines, it does not have a significant impact, perhaps increasing the flushing of the pipeline.
4. Advantages and disadvantages
A. Installation space:
The reduced bore ball valve has a small volume, so its installation space requirements are smaller. Due to its weight being about 30% lighter than full bore ball valves, it is beneficial for reducing pipeline load, transportation load, and cost.
B. Cost:
Reduced bore ball valves are one level cheaper than full bore ball valves. Considering cost-effectiveness, it is generally accepted internationally that adjacent pipe diameters use the same ball diameter valve body. DN32 and DN40, DN50 and DN63, DN90 and DN110, DN160 and DN200, and DN250 and DN315 use the same sphere.
Attention: Due to the smaller inner diameter of the reduced bore ball valve, the torque exerted on the valve stem is smaller, which is more suitable for extending the service life of the valve switch. Especially for the low torque design of large-diameter valves. However, the reduction in diameter cannot be significant, otherwise the system resistance will increase. However, if the diameter is not reduced, firstly it will increase the procurement cost. Secondly, it will generally reduce the valve control characteristics, resulting in a worse regulation effect. For example, if the regulating valve is always used at a small opening, it will reduce the service life of the valve.
