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a)
球阀
a) Ball Valves
优点－推荐
Positive Features - Recommendations
1) 无气泡关闭功能的弹性材料（聚四氟乙烯）阀座
1) Bubble-tight shut-off from resilient (TFE)
seats
2) 快速90o回转开启/关闭，扭矩与阀座密封无关
2) Quick 90° open/close, not torque-dependent
for seating
3) 流体经过阀门时阻力小，直接通过，且可双向流动
3) Straight-through unobstructed flow, bidirectional
4) 选择不缩径全流道结构时，压降最小
4) Minimal pressure drop if full-port selected
5) 可用作节流阀（根据应用环境决定）
5) Can be throttled (Application dependent)
6) 比多回转阀门更加易于自动化控制
6) Easier to automate than multi-turn valves
7) 比多回转阀门更加紧凑
7) More compact than multi-turn valves
8) 循环使用寿命更长
8) Offers high cycle life
缺点
Disadvantages
1) 温度范围受到阀座密封材料的限制
1) Temperature range limited by seat material
阀体结构
Body Styles
 1)
整体式：没有潜在的阀体泄漏通道，但是要求采用缩径流道球体；因此，压降明显。无法维修。
1) One-piece has no potential body leak path,
but requires use of reduced port ball; thus, significant pressure drop.
Not repairable.
 2)
两件侧装式：建筑物管道系统最常用结构。性价比最高。可配置不缩径全流道或标准流道球体。不易维修。
2) Two-piece end entry is most common in building
services. Best price value. Available full- or standard-port balls. Not
recommended to be repaired.
 3)
三件式：成本最高的结构，但是拆解容易，具有管内可修性。可配置不缩径全流道或标准流道球体。
3) Three-piece is more costly, but is easier
to disassemble and offers in-line repairability. Available in full- or
standard-port balls.
 4)
上装式：适用于某些工业领域，例如当要求在维修过程中，不能把阀体从管道上拆卸下来时，就需要这种结构的球阀。成本比两件式高。
4) Top entry is preferred in some industrial
applications where access for repair is required without removing body
from the line. More costly than two-piece
style.
端口尺寸
Port Size
 1)
不缩径全流道球阀具有不影响整个管道压降的性能，在此方面，甚至比闸阀性能更加优异。
1) Full-Port ball valves provide pressure drop
equal to equivalent length of pipe, and even slightly better than gate
valves.
 2)
标准（常规）流道球阀用于管道直径比管道公称通径小的管道，但是其流通能力仍然比截止阀好得多。
2) Standard (conventional) port balls are up
to one pipe size smaller than nominal pipe size, but still have significantly
better flow than globe valves.
 3)
缩径流道球阀流通能力较差，不推荐在建筑物管道系统中使用，但是可用于有害物质传输的处理管道。
3) Reduced port ball valves have more than one
pipe size flow restriction and are not recommended in building services
piping, but rather for process
piping in hazardous material transfer. |
