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อัปเดต 2026-09-07
Control valve
Cv / throttling
A throttling valve characterised by its flow coefficient Cv (or Kv). It imposes a pressure drop that varies with opening and flow.
เมื่อไรจึงใช้
- Flow/pressure regulation; setting a duty point; modelling a partly-open valve.
ค่าที่ต้องกรอก
| ค่า | คำอธิบาย |
|---|---|
| Cv / Kv | Flow coefficient at the modelled opening. |
| Opening % | Optional — scales Cv along the valve characteristic. |
คำนวณอย่างไร
We use the ISA-75.01 / IEC 60534 master sizing equation: the flow coefficient Cv relates flow to the pressure drop and specific gravity. Inverted, it gives the ΔP the valve imposes, which enters the network energy balance.
สมการ
ISA-75.01 master equation
G_f = liquid specific gravity, N₁ = unit constant (1.00 for Cv in US gpm·psi, 0.0865 for Kv in m³/h·kPa). Cv = 1.156·Kv.
Pressure drop across the valve
The imposed drop rises with the square of flow and falls with Cv² — closing the valve (lower Cv) raises ΔP.
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