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💨 风量 CFM 计算器（风管、换气次数、单位换算）CFM Calculator (Duct Airflow, Air Changes, Unit Conversion)
三种算法：由风管尺寸（圆形直径或矩形宽高）和风速 fpm 求风量 CFM；由房间尺寸和每小时换气次数 ACH 求所需 CFM；或在 CFM、m³/h、L/s、m³/min 之间换算。本地处理。Three ways: airflow in CFM from a duct size (round diameter or rectangular width and height) and air velocity in fpm, the CFM a room needs from its size and air changes per hour (ACH), or converting between CFM, m³/h, L/s and m³/min. Processed locally.
使用说明与常见问题How-to & FAQ
「风量 CFM 计算器（风管、换气次数、单位换算）」是什么？What is the CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) tool?
三种算法：由风管尺寸（圆形直径或矩形宽高）和风速 fpm 求风量 CFM；由房间尺寸和每小时换气次数 ACH 求所需 CFM；或在 CFM、m³/h、L/s、m³/min 之间换算。本地处理。Three ways: airflow in CFM from a duct size (round diameter or rectangular width and height) and air velocity in fpm, the CFM a room needs from its size and air changes per hour (ACH), or converting between CFM, m³/h, L/s and m³/min. Processed locally.
如何使用「风量 CFM 计算器（风管、换气次数、单位换算）」？How do I use the CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) tool?
在「风量 CFM 计算器（风管、换气次数、单位换算）」中，填写「算法」、「风管形状」、「直径（英寸）」、「宽（英寸）」、「高（英寸）」等参数，结果会随输入实时计算并显示在下方。In the CFM Calculator (Duct Airflow, Air Changes, Unit Conversion): Fill in "Method", "Duct shape", "Diameter (in)", "Width (in)", "Height (in)"; results are recalculated instantly as you type.
CFM 怎么算？How is CFM worked out?
风量 CFM = 截面积 (ft²) × 风速 (ft/min)。圆管面积 = π × (直径/12)² ÷ 4，矩形 = 宽 × 高 ÷ 144（英寸换算成平方英尺）。CFM = area (ft²) × velocity (ft/min). A round duct has area π × (diameter/12)² / 4 and a rectangular one width × height / 144 when measured in inches.
换气次数取多少？How many air changes should I use?
常见参考：卧室、客厅 4–6 次/小时，厨房 7–8 次以上，浴室 6–8 次。具体按当地规范和用途确定。Typical guides are 4–6 per hour for bedrooms and living rooms, 7–8 or more for kitchens and 6–8 for bathrooms. Local codes and use decide the real figure.
单位怎么换算？How do the units convert?
1 CFM ≈ 1.699 m³/h ≈ 0.4719 L/s ≈ 0.02832 m³/min。1 CFM is about 1.699 m³/h, 0.4719 L/s and 0.02832 m³/min.
能举个计算实例吗？Can you show a worked example?
例如在「风量 CFM 计算器（风管、换气次数、单位换算）」中填 算法 = 风管风速，风管形状 = 圆形，直径（英寸） = 8，风速 fpm = 700，单位 = CFM (ft³/min)，结果区显示：风量：244.3 CFM；截面积：0.3491 ft²；415.1 m³/h；115.3 L/s；6.919 m³/minFor example, entering Method = Duct and velocity, Duct shape = Round, Diameter (in) = 8, Velocity fpm = 700, Unit = CFM (ft³/min) in the CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) gives: Airflow: 244.3 CFM; Area: 0.3491 ft²; 415.1 m³/h; 115.3 L/s; 6.919 m³/min
哪些输入会被检查？Which inputs are validated?
「风量 CFM 计算器（风管、换气次数、单位换算）」会检查这些输入——「直径（英寸）」、「宽（英寸）」、「高（英寸）」、「风速 fpm」、「房间长（英尺）」、「房间宽（英尺）」、「层高（英尺）」、「每小时换气次数」、「风量」：所选方式用到时必须填写，须大于 0；绝对值超过 10¹⁵ 的数也会被拒绝。不符合时结果区显示具体提示，不会给出数字。The CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) checks its inputs — "Diameter (in)", "Width (in)", "Height (in)", "Velocity fpm", "Room length (ft)", "Room width (ft)", "Ceiling height (ft)", "Air changes per hour", "Airflow": required when the chosen option uses it, must be greater than 0; numbers above 10¹⁵ in absolute value are rejected too. When a value fails, the result area names the problem instead of showing a number.
有哪些选项可以调整？What options can I adjust?
「风量 CFM 计算器（风管、换气次数、单位换算）」的设置：「算法」可选 风管风速、房间换气次数、单位换算（默认 风管风速）；「风管形状」可选 圆形、矩形（默认 圆形）；「直径（英寸）」默认 8；「宽（英寸）」默认 12；「高（英寸）」默认 8；「风速 fpm」默认 700；「房间长（英尺）」默认 12；「房间宽（英尺）」默认 10；「层高（英尺）」默认 8；「每小时换气次数」默认 6；「风量」默认 100；「单位」可选 CFM (ft³/min)、m³/h、L/s、m³/min（默认 CFM (ft³/min)）。每次生成结果都按当前设置处理。Settings in the CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) — "Method": Duct and velocity, Room air changes, Convert units (default Duct and velocity); "Duct shape": Round, Rectangular (default Round); "Diameter (in)" default 8; "Width (in)" default 12; "Height (in)" default 8; "Velocity fpm" default 700; "Room length (ft)" default 12; "Room width (ft)" default 10; "Ceiling height (ft)" default 8; "Air changes per hour" default 6; "Airflow" default 100; "Unit": CFM (ft³/min), m³/h, L/s, m³/min…
计算结果可以用于作业或工程吗？Can I use the results for homework or engineering?
「风量 CFM 计算器（风管、换气次数、单位换算）」使用教科书标准公式（公式写在说明和常见问题中），适合学习和估算核对；涉及安全的工程设计请以规范和实测为准。The CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) uses standard textbook formulas (given in the description and FAQ), which is good for learning and checking estimates; for safety-critical engineering follow codes and measured values.
「风量 CFM 计算器（风管、换气次数、单位换算）」免费吗？需要注册吗？Is the CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) free? Do I need an account?
「风量 CFM 计算器（风管、换气次数、单位换算）」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The CFM Calculator (Duct Airflow, Air Changes, Unit Conversion) is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.