Ball valve VS. Gate valve
Ball valve VS. Gate valve
Valve is an indispensable key component in industrial production, municipal construction and residential life, from small household water pipes to large oil and gas long-distance pipelines, are inseparable from its control.
However, if you choose the wrong type of valve, it may lead to media leakage, system efficiency decline, and even trigger equipment failure and downtime losses. Ball valves and gate valves as the most widely used two types of valves, each with a clear design positioning and applicable scenarios. Understand their core differences, in order to make each selection is accurate to match the actual needs.
What is a ball valve? Core design and working principle
Ball valves belong to the angular stroke valve, its core component is a spherical valve with a center hole, the sphere is fixed in the valve body, through the valve stem and external handle or actuator connection.
When the handle is turned, the sphere rotates. When the holes in the sphere are perfectly aligned with the pipeline, the medium can pass through smoothly and the valve is in the fully open state; when the handle is rotated by 90 degrees (a quarter-turn), the sphere will block the pipeline passage completely, realizing that the valve is closed.
This design makes the ball valve structure compact, the overall volume is relatively small. Its sealing performance is excellent, the ball and the valve seat close fit, can effectively prevent the media leakage.
In addition, the ball valve supports multi-pass configuration, common three-way, four-way design, can realize the media diversion, mixing or flow switching, which is a lot of traditional valves do not have the advantage.
What is a gate valve? Core design and working principle
Gate valve is a straight stroke valve, mainly relying on vertical movement of the gate plate (wedge-shaped or disk-shaped) to control the flow of media. The gate is connected to the handwheel through the valve stem, which is divided into two types: open stem and concealed stem.
When the handwheel is turned, the stem will drive the gate up and down along the guide rail inside the valve body. When the gate is completely raised, the valve is fully open, at this time the medium can flow along the straight-through orifice without obstruction; when the gate is lowered to completely fit the valve seat, the valve is closed, to achieve media isolation.
Gate valve is designed to meet the needs of large flow, especially suitable for long-term fully open state, occasionally switching operation of the scene. It has a large cross-section of the flow, the medium flow resistance is small, which is its outstanding structural advantages.
Ball valves vs gate valves: core differences in comparison
Operation and switching speed
Ball valve operation is extremely simple, only need to rotate 90 degrees to complete the switch from fully open to fully closed, even in emergencies, but also a fast response. This feature makes it particularly suitable for systems that require frequent opening and closing, such as media control in automated production lines.
Gate valves, on the other hand, are cumbersome to operate, requiring the handwheel to be turned more than 360 degrees to fully raise or lower the gate. Its slow opening and closing process does not meet the need for quick response and is more suitable for scenarios that do not require frequent operation.
Flow control and throttling performance
The strong point of the ball valve is on/off control, which can quickly realize the medium on/off. However, it is not suitable for throttling regulation, if used for a long time in the partially open state, the high-speed flow of the medium will wash the ball and valve seat, resulting in wear and tear of the sealing surface, affecting the service life.
Gate valve is also not good at accurate throttling. When the gate is partially open, the medium will form an unstable flow state on both sides of the gate, which will not only produce large pressure fluctuations, but also may cause impact on the gate and stem, which will damage the valve components in the long term. It is more suitable for full flow or full closure conditions, to ensure the smooth flow of media or complete isolation.
Pressure loss
ball valve in partially open, the media flow path will be bent, resulting in relatively large pressure loss. Especially in high flow conditions, this pressure loss will be more obvious.
When the gate valve is fully open, the medium can flow along the straight channel, there is almost no additional resistance, the pressure loss is very small. This feature makes it more advantageous in the pressure loss sensitive, large flow transmission scenarios, such as large water supply pipelines, oil transmission pipelines.
Sealing performance
ball valve has a very reliable sealing effect, and the close fit between the ball and the valve seat can achieve a near-zero leakage seal. This feature makes it ideal for gas media transportation, such as natural gas pipelines, gas water heater connection lines, but also for liquid systems with strict sealing requirements.
The gate valve can achieve a better sealing effect when it is completely closed, meeting the isolation needs of general liquids. However, its sealing performance is greatly affected by gate wear and media impurities, and it is relatively easy to leak, so it is not very suitable for gases or scenarios with very high sealing requirements.
Installation Space Requirements
The compact size of the body of the ball valve takes up little space during installation, but manually operated ball valves need to reserve enough space for the handle to rotate (90-degree rotation range). However, for small-diameter pipelines, there are wing-shaped, round and other small handle ball valves on the market, which can be adapted to space-constrained installation environments, but the handle of large-diameter ball valves still require a certain amount of operating space.
Gate valve installation space requirements mainly from the valve stem lifting stroke, especially open stem gate valve, the valve stem will take up a certain amount of space above when rising, the overall installation volume is relatively large. However, its operating handwheel is small in size and does not require additional rotating space, so it is more suitable in some lateral space-restricted scenarios.
Media compatibility
ball valves are suitable for a wide range of media, whether it is water, oil, chemical reagents and other liquids, or natural gas, propane and other gases, can be stably adapted. Its good sealing performance can effectively avoid the leakage of different media pollution or safety hazards.
Gate valve is more suitable for conveying oil, sewage and other viscous or contain a small amount of impurities in the liquid. Due to the relatively weak sealing performance, it is easy to leak in the gas media transportation, so it is less used in gas systems.
Pass configuration options
ball valves support multi-pass design, in addition to the conventional two-way ball valves, three-way, four-way ball valves can realize the media diversion, merging or flow switching, for example, in chemical production, through the three-way ball valves can be mixed with the two raw materials transport, or to achieve the switching of the media in different pipelines.
Gate valve diameter configuration is relatively single, most of the two-way design, can only realize the straight line of the media on and off, can not meet the shunt, merge and other complex flow control needs, the flexibility of the diameter is far less than the ball valve.
Cost and durability
From the market price point of view, the same specifications of the ball valve is usually more affordable than the gate valve, especially in small diameter products, the price advantage is obvious. And the structure of the ball valve is relatively simple, less wear parts, as long as the routine maintenance of proper, long service life, long-term use of lower costs.
Gate valve manufacturing costs are higher, the price is generally higher than the ball valve. Its gate, valve stem and other parts in the switching process is susceptible to media washout and wear, if frequent operation, will accelerate the aging of parts, durability is relatively poor, maintenance frequency will be higher.
When to choose the ball valve? Applicable Scenarios
The advantages of ball valves are focused on fast operation, reliable sealing and multi-scenario adaptation, the following cases are preferred to choose ball valves:
Frequent switching systems, such as automation control of the media on and off, beverage production line raw material pipeline; emergency need to quickly cut off the medium of the scene, such as the chemical workshop of the hazardous materials pipeline, gas leakage emergency cut off system;
Gas media or the sealing of the liquid system, such as natural gas, the sealing requirements are strict. Strict requirements for the sealing of the liquid system, such as natural gas pipeline, laboratory reagent delivery pipeline; need to realize the media diversion, merging or flow switching scenes, such as the central air conditioning water circulation system, chemical reactor raw material proportioning pipeline;
installation space is limited, but do not need to frequently operate the large-diameter valve scenes, such as home plumbing, small industrial equipment piping system.
It is widely used in petrochemical, chemical processing, gas distribution, automated manufacturing and other industries, is a highly versatile type of valve.
When should I choose a gate valve? Applicable Scenarios
The core advantage of the gate valve is low pressure loss and large flow rate adaptation, the following situations are more suitable for the selection of gate valves:
Long-term fully open state, occasional switching operation of the scenario, such as municipal water main pipeline, power plant cooling water circulating mains; occasions requiring large flow rate of the medium transported, such as water supply pipelines for large reservoirs, long-distance pipeline for petroleum;
Strict requirements for pressure loss system, such as high-pressure Boiler water supply pipe, industrial cooling water circulation system; conveying viscous liquids or media containing a small amount of impurities, such as crude oil pipeline, sewage discharge main road.
It is commonly used in municipal infrastructure, power plants (steam, condensate, cooling water system), oil and gas long-distance pipeline, large industrial equipment, such as high-flow pipelines.
Summary of advantages and disadvantages: ball valves and gate valves
Ball valves
Advantages: fast and easy operation, reliable sealing performance, wide range of applicable media, support for multi-pass configuration, compact body structure, economic price, durability, low maintenance costs.
Disadvantages: partially open when the pressure loss is large, not suitable for long-term throttling, high temperature environment sealing materials are easy to aging, large diameter ball valve operation requires sufficient handle space.
Gate Valve
Advantages: small pressure loss when fully open, strong flow capacity, suitable for large-diameter pipelines, adaptable to viscous liquids, good sealing effect when fully closed, suitable for media isolation.
Disadvantages: slow switching speed, not suitable for frequent operation, poor throttling performance, large installation space requirements, relatively high prices, the sealing surface is susceptible to wear and tear of media impurities, durability in general.
Selection expert advice
First clear operating frequency: if you need frequent switching, prioritize ball valves; if the long-term full open, occasional operation, gate valve is more appropriate.
Determine the type of transport media: gas media or high sealing requirements of the liquid, choose ball valves; viscous liquids or liquids containing a small amount of impurities, you can consider the gate valve.
Evaluate the flow control needs: only simple on and off or need a quick shut-off, choose ball valves; the need for high-flow transportation, sensitive to pressure loss, choose gate valves.
Consider the installation space conditions: limited lateral space, the need for compact installation, choose ball valves; longitudinal space is sufficient to accommodate the valve stem lift, gate valves are more suitable.
Check the diameter configuration needs: the need for diversion, merging or flow switching, only ball valves; only straight line through, both can be combined with other factors in the decision-making.
Accounting for costs and maintenance budget: limited budget, hope that long-term low maintenance, ball valves have more advantages; not sensitive to cost, the pursuit of large flow and low resistance, you can choose the gate valve.
Conclusion
Ball valves and gate valves have no absolute advantages and disadvantages, the key lies in whether to match the specific application scenarios.
Ball valves with fast operation, reliable sealing and multi-scene adaptive features, suitable for dynamic, demanding industrial environment and civil scenarios; gate valves with low pressure loss, large flow adaptive advantages in municipal construction, long-distance transmission and other fields occupy an important position.
When selecting the type, you only need to combine the frequency of operation, media type, flow demand, installation space and cost budget and other factors, you can make a suitable choice. If you encounter complex conditions or uncertainty in the selection needs, it is recommended to consult a professional valve technician to obtain a more accurate program.
Frequently Asked Questions (FAQs)
Q1: Can ball valves be used for throttling regulation?
It is not recommended to be used for throttling adjustment for a long time. The sealing surface of the ball valve is easily worn by the high-speed flow of the media scouring, long-term partial opening will affect the sealing performance and service life, only suitable for temporary simple throttling.
Q2：Are gate valves suitable for gas media transportation?
Not very suitable. Gate valve sealing performance is relatively weak, the small size of the gas medium molecules, easy to leak from the sealing gap, there are security risks, gas transportation priority ball valves.
Q3：Which is more durable, ball valve or gate valve?
Under the premise of normal maintenance and suitable working conditions, ball valve is more durable. It has fewer wear parts and simple structure, while the gate and stem of gate valve are easy to be washed by the medium, and frequent operation will accelerate the aging.
Q4: Does a ball valve require more installation space than a gate valve?
Not necessarily. Ball valve body is compact, small installation space, but need to reserve space for handle rotation; gate valve body is large, especially the open-stem model requires longitudinal installation space, but the operation of the handwheel does not require additional rotating space, need to be based on the installation environment specific judgment.
Q5：Can gate valves withstand high temperature environment?
Gate valves are suitable for some high-temperature scenarios, such as steam piping in power plants. However, the specific ability to withstand high temperatures depends on the material of the valve, the choice of high-temperature-resistant materials (such as alloy steel) gate valve, can be adapted to high-temperature liquid or steam system.
Q6: What are the main advantages of multi-way ball valves?
Multi-pass ball valves (three-way, four-way) can achieve a variety of flow control functions in a valve, such as diversion, merging, flow switching, without the need to install multiple additional valves, simplifying the pipeline design, reducing installation costs and space occupation.
