русскийДисковый затвор vs задвижка: ключевые отличия и руководство по выбору
В промышленных трубопроводных системах дисковые затворы и задвижки являются одними из наиболее широко применяемых запорных клапанов. Несмотря на схожесть функций, различия в конструкции, гидравлических характеристиках и способах управления могут напрямую влиять на эффективность системы, требования к обслуживанию и её долгосрочную надежность.
В этой статье представлен системный сравнительный анализ дисковых затворов и задвижек с точки зрения принципа работы, эксплуатационных характеристик и областей применения. Цель — помочь читателям сформировать более четкий подход к выбору и принимать обоснованные, экономически эффективные решения в реальной инженерной практике.
Что такое дисковый затвор?
Дисковый затвор — это поворотный клапан четвертьоборота, который открывает или перекрывает поток за счет поворота круглого диска на 90° внутри трубопровода. Такая конструкция обеспечивает компактность, быстрое срабатывание и особенно хорошо подходит для трубопроводов большого диаметра.
Что такое задвижка?
Задвижка — это клапан с поступательным движением запорного элемента, который открывает или перекрывает поток за счет подъема или опускания затвора вдоль седел. В полностью открытом положении затвор полностью выходит из проточной части, позволяя рабочей среде проходить практически по прямой линии. По этой причине задвижки обычно применяются в системах, где требуется полностью открытое или полностью закрытое положение, а не регулирование потока.
Butterfly Valve vs Gate Valve: Fundamental Difference
The most fundamental distinction between butterfly valves and gate valves lies in the spatial relationship between the closing element and the flow path when the valve is open. This structural difference is the primary source of nearly all variations in performance and application.
- Butterfly Valve: The disc remains within the flow path at all times. While this design may introduce some flow resistance, it also allows for a more compact structure and reduced weight.
- Gate Valve: When fully open, the gate is completely withdrawn from the flow path, enabling the medium to pass through in a near-straight line and effectively minimizing pressure loss.
Butterfly Valve vs Gate Valve: Key Performance Comparison
1. Flow Resistance and Pressure Loss
Even when fully open, the disc remains within the flow path, which typically results in some degree of pressure loss. However, in most water supply and industrial systems, this impact is generally within an acceptable range.
When opened, the gate is completely withdrawn from the flow path, resulting in lower flow resistance. This characteristic is advantageous for reducing pressure loss and improving overall flow efficiency.
2. Structural Weight
- Butterfly Valve:
With a compact design and lower material usage, butterfly valves are typically lighter than gate valves of the same size. This advantage becomes particularly noticeable in large-diameter applications.
- Gate Valve:
Because the valve body must accommodate the vertical travel of the gate, the overall structure is larger and heavier. As a result, higher support requirements are often necessary during installation.
3. Installation Space
- Butterfly Valve:
With a short face-to-face dimension and lower overall height, butterfly valves require less installation space. They are well suited for compact equipment layouts or valve chambers with limited space.
- Gate Valve:
Gate valves typically have greater overall height, especially in large-diameter applications. Adequate vertical clearance must be reserved to accommodate installation and operation.
4. Operating Speed and Actuation
- Butterfly Valve:
Its quarter-turn design results in a shorter operating stroke and faster opening and closing. This makes butterfly valves particularly suitable for systems that require frequent operation.
- Gate Valve:
Gate valves rely on the vertical movement of the gate to open and close, resulting in a longer operating stroke. Opening and closing generally take more time, and they are typically used in applications with lower operating frequency.
5. Flow Control Capability
- Butterfly Valve:
When partially open, a butterfly valve can provide a certain degree of flow control. However, prolonged throttling may accelerate seat wear.
- Gate Valve:
Gate valves are better suited for fully open or fully closed conditions. Operating them in a partially open position for extended periods may increase erosion on the sealing surfaces, which is why they are generally not used for flow regulation.
6. Sealing Performance and Durability
- Butterfly Valve:
Butterfly valves can achieve reliable sealing, but performance depends largely on seat materials, structural design, and manufacturing quality. As a result, sealing capability may vary between products.
- Gate Valve:
When fully closed, gate valves typically provide stable sealing and are well suited for applications that require tight shut-off. This performance assumes relatively clean media, as fluids containing solid particles may scratch or damage the sealing surfaces.
When to Choose a Butterfly Valve vs a Gate Valve
In industrial pipeline systems, neither butterfly valves nor gate valves are inherently superior. The key consideration is whether the valve aligns with the specific demands of the operating conditions.
Situations Where a Butterfly Valve Is Often Preferred:
- Medium- to large-diameter pipelines
- Limited installation space
- Systems requiring frequent operation or quick response
- Higher levels of automation
- Greater emphasis on overall cost efficiency and ease of maintenance
Situations Where a Gate Valve Is Often Preferred:
- Pipelines sensitive to pressure loss
- Applications that require the valve to remain fully open or fully closed for extended periods
- Critical pipeline sections where reliable isolation is essential
- Minimal need for flow regulation
- Installations with relatively sufficient space
From an engineering perspective, neither butterfly valves nor gate valves should be viewed as universally superior. The key lies in whether the valve’s characteristics align with the actual operating conditions. A well-informed selection based on system requirements is essential for achieving stable, predictable performance over the long term.
Union Valve specializes in the design and manufacture of butterfly and gate valves, providing reliable flow control solutions for municipal and industrial pipeline systems. We also support project evaluations by helping identify valve options that best match specific application needs. If you have any questions, please feel free to contact us.
FAQ
If the budget is limited, should a lower-cost butterfly valve always be selected?
Not necessarily.
While butterfly valves typically offer a lower initial purchase cost, valve selection should not focus solely on upfront pricing. Operating efficiency, maintenance requirements, and lifecycle cost should all be considered.
If the system is sensitive to pressure loss, requires long-term full-open operation, or demands highly reliable isolation, choosing a butterfly valve based on price alone may lead to higher energy consumption and maintenance expenses over time.
If butterfly valves can also provide shut-off, why are gate valves often recommended for critical isolation points?
Critical isolation points place greater emphasis on certainty of isolation and long-term reliability. When closed, a gate valve forms a clear metal or surface contact seal, making the isolation status more predictable and suitable for important pipeline sections that remain fully open or fully closed.
Butterfly valves can also achieve effective shut-off, but their sealing performance depends more heavily on structural design, seat materials, and alignment with operating conditions. In locations with higher safety requirements, engineering practice often favors solutions with more controllable operational risk.
