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Technical 24th March 2026

Full Port vs Reduced Port Ball Valve: Flow, Pressure Drop & Cost Comparison

Key Takeaway

A full port ball valve has a bore diameter matching the pipe ID, delivering near-zero flow restriction and 30–50% higher Cv than a reduced port design. A reduced port valve uses a bore one or two sizes smaller than the pipe, costing 15–30% less. Choose based on your system's pressure drop tolerance, Cv requirements, and budget.

Full Port Bore = Pipe ID (25.4mm for 1") Cv = 60 | Near-zero pressure drop Reduced Port Bore = Pipe ID - 1 size (19mm for 1") Cv = 30 | +100% pressure drop 1" Ball Valve Comparison (ASME B16.34)

What Is a Full Port Ball Valve?

A full port (also called "full bore") ball valve has a ball bore diameter equal to the nominal pipe ID. For example, a 1-inch full port valve has a ~25.4mm bore that matches a Schedule 40 pipe. When fully open, the fluid passes through with virtually no pressure drop. Per API 608 and ISO 17292, full port valves must achieve a Cv at least 90% of the theoretical maximum pipe flow.

Best applications: Pipeline pigging, high-viscosity fluids, systems requiring maximum flow (e.g., data center CDU main loops).

What Is a Reduced Port Ball Valve?

A reduced port ball valve has a bore one nominal size smaller than the pipe. For example, a 1-inch reduced port valve has a ~19mm bore (equivalent to a 3/4" pipe). The fluid accelerates through the constriction, creating additional pressure drop.

Best applications: Branch lines, low-flow systems, cost-sensitive bulk orders (e.g., HVAC branch piping).

How Do Cv Values Compare Between Full Port and Reduced Port?

Valve Size Full Port Cv Reduced Port Cv Cv Difference Pressure Drop Impact
1/2" 18 8 -56% +125%
3/4" 34 17 -50% +100%
1" 60 30 -50% +100%
1-1/2" 130 70 -46% +86%
2" 220 120 -45% +83%

Data based on ASME B16.34 standards and LINS Valve product testing.

Which Should You Choose for Data Center Liquid Cooling?

For AI data center CDU (Coolant Distribution Unit) systems, LINS Valve recommends:

Location in System Recommended Port Reason
Main Loop Full Port Unrestricted glycol-water coolant flow for maximum heat dissipation
CDU Isolation Valves Full Port 3PC Maintenance access without system shutdown
Branch Lines Reduced Port Lower flow requirements, cost savings
Server Rack Supply/Return Reduced Port Adequate flow for individual rack cooling
Bypass Lines Full Port Must handle full system flow during maintenance
CDU System — Valve Port Selection Guide CDU Unit Coolant Distribution Unit FULL PORT FULL PORT RP RP RP RP Rack 1 Rack 2 Rack 3 Rack 4 Full Port — Main Loop (max flow) Reduced Port — Branch Lines (cost saving)

Frequently Asked Questions

Can full port ball valves be used for pipeline pigging?
Yes. Full port is required for pigging operations because the pig must pass through the valve unobstructed. Reduced port valves block pig passage due to the smaller bore.
Does a reduced port valve affect system efficiency?
It depends on the system. In low-velocity systems (e.g., HVAC branches), the added pressure drop is negligible. In high-velocity or pressure-sensitive systems (e.g., chemical processing), full port is preferred.
What sizes does LINS Valve offer in full port?
LINS Valve manufactures full port SS316 ball valves from 1/4" to 4", available in NPT, BSP, Socket Weld, and flanged connections. Certifications include ISO 9001:2015, CSA, and WRAS.

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全通徑 vs 縮徑球閥：流量、壓降與成本完整比較

重點摘要

全通徑（Full Port）球閥的閥球通道與管道內徑一致，提供近乎零阻力的流體通路，Cv 值比縮徑型高 30–50%。縮徑（Reduced Port）球閥的通道比管道小一到兩個尺寸，成本低 15–30%，適合壓降不敏感的應用。選擇取決於你的系統對壓降容忍度、流量係數（Cv）需求和預算。

什麼是全通徑球閥？

全通徑球閥的閥球孔徑（bore）等於管道標稱內徑（ID）。例如，1 英寸全通徑球閥的通道直徑約為 25.4mm，與 Schedule 40 管道匹配。當閥門全開時，流體通過幾乎沒有壓降——這就是為什麼 API 608 和 ISO 17292 標準要求全通徑閥的 Cv 值達到管道理論最大流量的 90% 以上。

典型應用：管道清管（pigging）、高黏度流體、需要最大流量的系統（如數據中心 CDU 主管路）。

什麼是縮徑球閥？

縮徑球閥的閥球通道比管道小一個標稱尺寸。例如，1 英寸縮徑球閥的通道直徑約為 19mm（相當於 3/4 英寸管道）。這意味著流體在通過時會加速，產生額外的壓降。

典型應用：分支管路、低流量系統、成本敏感的批量採購（如 HVAC 系統支管）。

Cv 值對照表：全通徑 vs 縮徑

閥門尺寸 全通徑 Cv 縮徑 Cv Cv 差異 壓降差異
1/2"188-56%+125%
3/4"3417-50%+100%
1"6030-50%+100%
1-1/2"13070-46%+86%
2"220120-45%+83%

數據來源：基於 ASME B16.34 標準和 LINS Valve 產品實測數據

數據中心液冷系統怎麼選？

在 AI 數據中心的 CDU（Coolant Distribution Unit）系統中，LINS Valve 建議：

Cv Flow Coefficient Comparison by Size 1/2" Cv 18 Cv 8 3/4" Cv 34 Cv 17 1" Cv 60 Cv 30 Full Port Reduced Port Higher Cv = more flow Source: ASME B16.34

常見問題

全通徑球閥可以用於管道清管（pigging）嗎？
是的，全通徑球閥是管道清管的必要條件，因為清管器（pig）需要無障礙地通過閥門。縮徑球閥的通道太小，清管器無法通過。
縮徑球閥會影響系統效率嗎？
取決於系統設計。在低流速系統中（如 HVAC 支管），額外的壓降通常可以忽略。但在高流速或對壓降敏感的系統中（如化工管路），應優先選擇全通徑。
LINS Valve 提供哪些尺寸的全通徑球閥？
LINS Valve 提供 1/4" 到 4" 的全通徑 SS316 球閥，支援 NPT、BSP、Socket Weld 和法蘭連接。認證包含 ISO 9001:2015、CSA、WRAS。

相關文章

LINS Valve: Need help choosing between full port and reduced port for your system? Our engineering team provides expert guidance based on your flow, pressure, and media requirements. 80+ years of manufacturing experience serving Fortune 500 OEM partners.
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