✓التحكم في التدفق SMD
•Published: 2026-05-28•⏱ 6 دقيقة قراءة
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Check valves must close automatically as flow reverses, but different constructions respond at different speeds and with different pressure loss. A swing check provides a clear flow path and is common in many services, while a dual-plate wafer valve offers a compact installation envelope.
Tilting-disc and axial-flow designs can be considered where closing response and dynamic behavior are important. The correct choice depends on flow velocity, density, line size, system deceleration, pump or compressor behavior, installation orientation and allowable pressure drop.
Do not select only by line size and class. Define the normal and minimum flow, transient conditions, preferred orientation, cracking pressure, leakage requirement, end connection and maintenance access. For critical systems, the system designer should evaluate water-hammer and dynamic response.
The RFQ should also identify materials, product standard, inspection requirements and any special trim, spring or damping arrangement.
Engineering Q&A
Technical FAQ & Design Criteria
Critical engineering answers referenced against API / ASME / ISO standards.
Why are axial-flow nozzle check valves superior for non-slam compressor and pump discharge duties?↓
Axial-flow check valves utilize a streamlined disc and spring assistance with a very short travel stroke. When flow decelerates, the disc closes before reverse flow velocity establishes, preventing severe hydraulic shock (water hammer).
Can a swing check valve be installed in a vertical downward flow line?↓
No. Standard swing check valves rely on gravity and forward flow to hold the disc open. In vertical downward flow, gravity holds the disc in the open position even during reverse flow, preventing proper shutoff.
What is the minimum flow velocity required to keep a dual-plate check valve fully open?↓
Dual-plate wafer check valves typically require a minimum flow velocity of 1.5 to 2.5 m/s for liquids (and 15 to 25 m/s for gases) to keep the spring-loaded plates stably pinned against the stop pin without flutter-induced hinge pin wear.
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صمام عدم رجوع Selection Guide: Swing, Lift, Dual Plate, and Piston Types
Official engineering resource by SMD Flow Control
