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全啟式安全閥

全啟式安全閥在達到整定壓力時瞬間全開，釋放全部喉部面積，使鍋爐、儲氣罐與容器周圍可壓縮或兩相服務的積壓迅速下降。產品範圍涵蓋彈簧加載結構，閥體為鑄鐵、WCB、SS304 或 SS316，內件組——噴嘴、調節環、閥盤、導向套與閥桿——為 2Cr13、SS304 或 SS316，碳鋼閥蓋與罩帽、鋼彈簧與 2Cr13 調整螺栓。工作壓力涵蓋 PN1.6 至 PN4.0 與 Class 150 至 Class 300，端接 NPT、RF 或 RTJ。設計依 API 520/521/526/527 洩放系列與 ASME 25.3，面距依 ASME B16.10、EN 558-1 或 DIN 3202，法蘭依 ASME B16.5、DIN 2543/2545 或 EN 12627，測試依 API 598 / DIN 323。操作處於狹窄邊際：約 10% 超壓（按規範為 3%-21%）換取全開啟，啟閉壓差（blowdown）-4% 至 -20% 決定回座點，且操作壓力必須低於回座點以避免前洩（simmer）——即 90-95% 整定壓力附近開始的閥座與閥盤間可聞洩漏。顫振（chatter）是可達數百赫茲的閥座-閥盤快速振盪，成因為入口損失過大（不可恢復的累計入口損失在銘牌排量下必須保持在整定壓力的 3% 以內）或選型過大，表現為閥座損傷、彈簧疲勞與閥桿咬傷；API 527 將金屬閥座洩漏限制在 90% 整定壓力，API 526 的 D-T 字母孔口框架面積選擇。選型取決於整定壓力對工作壓力區間、閥座與噴嘴材料對介質，以及管線的螺紋或法蘭端接。

屬於安全閥系列

最後更新： 2026-11

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系列規格

Set-pressure range	0.1-10 MPa (0.1-2 at class 150; 1.6-5 at class 300; 3.2-10 at class 600)
Nominal valve connection size	DN32–DN150
Valve body material	Cast Iron, WCB, SS304, SS316
Nozzle Materials	2Cr13, SS304, SS316
Disc Materials	2Cr13, SS304, SS316
End connection types	NPT, RF, RTJ
Service temperature range	≤300°C
Design standards	ASME 25.3, API 520, API 521, API 526, API 527
Inspection and pressure-test standards	API 598, DIN 323
Face-to-face dimensional standard	ASME B16.10, EN558-1, DIN 3202
adjusting ring materials	2Cr13, SS304, SS316
guide sleeve materials	2Cr13, SS304, SS316
Bonnet material	Carbon Steel
spring materials	Steel
Stem material	2Cr13, SS304, SS316
adjusting bolt materials	2Cr13
cap materials	Carbon Steel
Working pressure (source-defined)	PN1.6, PN2.5, PN4.0, Class 150 to Class 300
Flange standards	ASME B16.5, DIN 2543, DIN 2545, EN 12627
overpressure allowance 10pct full lift	ASME/API practice allows roughly 10% overpressure for valves on unfired systems so the pop-action valve can achieve full lift and rated capacity; the huddling chamber assists the lift effort
overpressure typical range leser	Overpressure is usually expressed as a percentage of set pressure; a typical value is 10%, ranging between 3% and 21% depending on the code and application
blowdown definition crosby	Blowdown is the difference between the set pressure and the closing-point (reseat) pressure, expressed as a percentage of set pressure; where the closing point sits is determined by the control-chamber design
blowdown typical values leser	Typical blowdown values defined in codes and standards are -7% and -10%, ranging from -4% to -20% depending on the code and service (steam, gas or liquid)
operating margin vs blowdown crosby m11	Operating pressure must stay below the reseating pressure: set at 100 psig with 7% blowdown the valve closes at 93 psig, so operation must remain below 93 psig to prevent leakage or flow from a partially open valve
inlet loss 3pct rule crosby	Inlet piping rule: the cumulative total of all non-recoverable inlet losses shall not exceed 3% of the valve set pressure, evaluated at nameplate capacity corrected for the flowing fluid; upstream system flow characteristics govern
chatter definition and causes valfonta	Chatter is the rapid oscillation of the plug on the valve seat - not ordinary vibration - with the moving component repeatedly striking the metal seat at frequencies that can reach hundreds of hertz; main drivers are excessive inlet-pipe pressure loss, oversizing and too-narrow blowdown margin, with seat/plug deformation, spring fatigue and stem galling as the damage modes
chatter cause summary projectmaterials	Chatter is rapid opening and closing of the valve disc, caused by excessive inlet pressure drop (over 3% of set pressure) or an oversized valve; simmer on spring-loaded valves begins at approximately 90-95% of set pressure
simmer definition crosby	Simmer is the audible or visible escape of fluid between the seat and disc at an inlet static pressure below the popping pressure and at no measurable capacity; it applies to safety or safety relief valves on compressible-fluid service
api527 seat leakage and api526 orifice	API 527 seat-tightness testing applies 90% of set pressure and limits metal-seated gas valves to 40 SCFH air up to 1,000 psig, and 0.60 SCFH air per inch of orifice diameter above 1,000 psig, while soft-seated valves must show zero leakage; API 526 standardizes orifice sizes by letter designation D through T, selected as the next larger standard orifice after the API 520 Part I required area
adjusting ring	2Cr13, SS304, SS316
guide sleeve	2Cr13, SS304, SS316
adjusting bolt	2Cr13
end connection	NPT, RF, RTJ
end connection dimension	ASME B16.5, DIN 2543, DIN 2545, EN 12627

範圍與來源備註

overpressure wording	Overpressure wording: Crosby handbook gives the general 10% allowance for valves on unfired systems, while LESER states the code range spans 3%-21% by code and application; the page should quote 10% as typical, not as a universal limit.