減壓閥的基礎功能與原理

　　Basic functions and principles of pressure reducing valves

　　核心作用將高壓氣體（鋼瓶/管道）降至安全穩定的工作壓力，防止設備損壞或爆炸。自動調節出口壓力，即使入口壓力波動（如鋼瓶用盡時）也能保持輸出穩定。

　　The core function is to reduce high-pressure gas (steel cylinders/pipelines) to a safe and stable working pressure, preventing equipment damage or explosion. Automatically adjust the outlet pressure to maintain stable output even if the inlet pressure fluctuates (such as when the steel cylinder is exhausted).

　　工作原理通過彈簧隔膜結構感應壓力變化，動態調整閥門開合度（例：入口壓力降低時開度增大以維持輸出，入口壓力上升時開度減小以維持輸出）。關鍵組件：調節手柄、針閥、隔膜腔，協同實現“高壓→低壓”的精準轉換。

　　The working principle is to dynamically adjust the valve opening and closing degree by sensing pressure changes through a spring diaphragm structure (for example, when the inlet pressure decreases, the opening degree increases to maintain output, and when the inlet pressure increases, the opening degree decreases to maintain output). Key components: adjusting handle, needle valve, diaphragm chamber, working together to achieve precise conversion from high pressure to low pressure.

　　02?減壓閥選型硬核指南

　　02 Hard core guide for selecting pressure reducing valves

　　選型關鍵參數減壓閥的材質和適用介質：在選擇減壓閥材質時，必須確認材質與氣體的兼容性，包括減壓閥密封材料。銅鍍鉻或黃銅減壓閥：常用于惰性氣體（氦氣、氮氣、氬氣）、常見的工業氣體（氧氣、氫氣）等，具有價格優勢。316L不銹鋼減壓閥：適用于高純氣體、低溫氣體、酸性氣體、堿性氣體等。減壓閥進出口壓力表的選擇和工作壓力范圍進出口壓力表的量程建議選擇系統最大壓力的1.5倍。減壓閥的工作壓力建議使用減壓閥工作范圍全量程的 1/3 ～ 2/3。減壓閥的精度控制控制精度：一般減壓閥的輸出控制壓力的精度為±0.5% FS，R30的工作范圍為10~50psi，輸出壓力的穩定性可達±0.125psi。若氣體使用點要求穩定的氣體壓力，建議安裝二級減壓閥，保持穩定的氣體壓力輸出。減壓閥的流量選擇要求參數解讀：橫軸 (X軸)：通常代表流量 ，單位如 L/min, m?/h, GPM 等。縱軸 (Y軸)：通常代表出口壓力 ，單位如 bar, psi, kPa 等。

　　Key parameters for selecting the material and applicable medium of the pressure reducing valve: When selecting the material of the pressure reducing valve, it is necessary to confirm the compatibility between the material and the gas, including the sealing material of the pressure reducing valve. Copper chrome plated or brass pressure reducing valve: commonly used for inert gases (helium, nitrogen, argon), common industrial gases (oxygen, hydrogen), etc., with price advantages. 316L stainless steel pressure reducing valve: suitable for high-purity gases, low-temperature gases, acidic gases, alkaline gases, etc. The selection of inlet and outlet pressure gauges for pressure reducing valves and the recommended range for inlet and outlet pressure gauges are 1.5 times the maximum system pressure. It is recommended to use 1/3 to 2/3 of the full range of the working pressure of the pressure reducing valve. Precision control precision of pressure reducing valve: The precision of the output control pressure of a general pressure reducing valve is ± 0.5% FS, the working range of R30 is 10-50psi, and the stability of the output pressure can reach ± 0.125psi. If the gas usage point requires a stable gas pressure, it is recommended to install a secondary pressure reducing valve to maintain a stable gas pressure output. Parameter interpretation for flow selection requirements of pressure reducing valves: horizontal axis (X-axis): usually represents flow rate, with units such as L/min, m ?/h, GPM, etc. Vertical axis (Y-axis): usually represents outlet pressure, with units such as bar, psi, kPa, etc.

　　曲線形狀：展示在特定入口壓力和設定壓力下，出口壓力如何隨流量的變化而變化。設定壓力點?無流量或極小流量（如關閉點）時，通過調節彈簧預設的出口壓力目標值，對應曲線中流量趨近于零的Y軸截距點。工作范圍減壓閥可穩定維持出口壓力偏差的流量區間，超出后壓力失穩或流量不足。下垂特性?流量增加導致出口壓力下降的現象，表現為曲線的負斜率。斜率絕對值越大（曲線越陡），穩壓性能越差；斜率趨零（曲線平緩）則穩壓性優。

　　Curve shape: Show how the outlet pressure changes with flow rate under specific inlet pressure and set pressure. When setting a pressure point with no or minimal flow (such as a closing point), adjust the preset outlet pressure target value of the spring to correspond to the Y-axis intercept point in the curve where the flow approaches zero. The working range of the pressure reducing valve can stably maintain the flow range of the outlet pressure deviation, beyond which the pressure becomes unstable or the flow is insufficient. The phenomenon of an increase in flow rate leading to a decrease in outlet pressure, manifested as a negative slope of the curve. The larger the absolute value of the slope (the steeper the curve), the worse the voltage stabilization performance; If the slope approaches zero (the curve is gentle), the stability is better.

　　成因：閥口節流壓降、閥芯位移對抗彈簧力、流道阻力上升；最大流量點保持出口壓力不低于設計下限時的最大流量閾值，超限后壓力驟降。曲線中右側拐點或終止點流量值。入口壓力影響入口壓力升高時曲線整體上移。選型需參考最低入口壓力對應的曲線。結構差異- 直接作用式：入口壓力降低時下垂量增大（穩壓性減弱）；

　　Cause: Pressure drop due to throttling at the valve port, displacement of the valve core against spring force, and increase in channel resistance; The maximum flow point maintains the outlet pressure not lower than the maximum flow threshold when the design lower limit is reached, and the pressure drops sharply after exceeding the limit. The flow value at the right inflection point or termination point in the curve. The inlet pressure affects the overall upward movement of the curve when the inlet pressure increases. The selection should refer to the curve corresponding to the lowest inlet pressure. Structural difference - direct action formula: When the inlet pressure decreases, the sag increases (the stability decreases);

　　- 先導式：入口壓力變化對下垂量影響?。ǚ€壓性優）。減壓閥的不同功能帶過濾功能的減壓閥帶電子控制的減壓閥帶安全泄壓的減壓閥

　　-Pilot type: The change in inlet pressure has little effect on the sag (excellent stability). Different functions of pressure reducing valves: pressure reducing valves with filtering function, pressure reducing valves with electronic control, and pressure reducing valves with safety relief

　　03案例分析

　　03 Case Analysis

　　前提條件：入口壓力為2.0Mpa，向工件內部充1.6MPa氮氣，工件容積10L，壓力控制精度±0.5%，要求在2s內充滿。由于是氮氣且壓力控制精度不高，所以選擇性價比高的黃銅減壓閥。工作壓力在減壓閥的量程范圍內，滿足要求。通過選型手冊可以找到上面的型號滿足要求，下面驗證一下流量是否滿足要求？

　　Prerequisite: The inlet pressure is 2.0Mpa, and 1.6MPa nitrogen gas is filled into the interior of the workpiece. The workpiece volume is 10L, and the pressure control accuracy is ± 0.5%. It is required to be filled within 2 seconds. Due to the nitrogen gas and low pressure control accuracy, a cost-effective brass pressure reducing valve is chosen. The working pressure is within the range of the pressure reducing valve and meets the requirements. Through the selection manual, we can find the models above that meet the requirements. Now, let's verify if the flow rate meets the requirements?

　　平均流量 ≈ 0.6 × 起始流量；（起始流量 = 充氣開始時容器壓力為大氣壓時的瞬時流量）系數 0.6 是工程經驗值，適用于大多數從常壓充到 50%~80% 氣源壓力的場景；目標壓力≤ 50% 氣源壓力取0.7，誤差約 ±10%；目標壓力≈80%氣源壓力取0.5，誤差約 ±15%；根據流量特性曲線圖，做入口壓力2.0MPa與入口壓力1334psi的平行線，大致可以知道當出口壓力是1.5MPa時，起始流量大致為4000SCFH，所以平均流量為2400 SCFH=67946.4 L/min=1132.44 L/s。（1 SCFM=0.028311m^3/min=28.311L/min）t = 容器容積*(目標壓力 - 大氣壓）/平均流量 。t=1.5*10*10/2 s= 75 L/s ＜ 1132.44 L/s，滿足要求，可以選擇此款減壓閥。

　　Average traffic ≈ 0.6 x initial traffic; The coefficient of 0.6 (initial flow rate=instantaneous flow rate when the container pressure is at atmospheric pressure at the beginning of inflation) is an engineering empirical value, suitable for most scenarios where the gas source pressure is increased from atmospheric pressure to 50%~80%; The target pressure is ≤ 50%, and the gas source pressure is taken as 0.7, with an error of about ± 10%; The target pressure is approximately 80%, and the gas source pressure is taken as 0.5, with an error of about ± 15%; According to the flow characteristic curve, draw parallel lines between the inlet pressure of 2.0MPa and the inlet pressure of 1334psi. It can be roughly known that when the outlet pressure is 1.5MPa, the initial flow rate is approximately 4000SCFH, so the average flow rate is 2400 SCFH=67946.4 L/min=1132.44 L/s. (1 SCFM=0.028311m ^ 3/min=28.311L/min) t=container volume * (target pressure atmospheric pressure)/average flow rate. t=1.5*10*10/2 s= 75 L/s ＜ 1132.44 L/s， If the requirements are met, this pressure reducing valve can be selected.

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