气密性测试仪主要是通过比较被测房间（腔体）内外的空气压力来计算房间的气密性，测试时，人工对房间进行增压或减压，造成房间内外的空气压力差异，产生空气流动，利用流量计测得流量，从而计算出房间通过大小不同的洞流出外面的空气量。
气体防护区气密性测试系统，主要检验建筑物（建筑围护结构）整体气密性以及外门窗或任意局部面积的空气泄漏检测，现执行的主要是NFPA 附录A和C、FM4-9、CIBSE TM23、NEN 2686等相关标准。气体防护区气密性测试有以下几个参数：
l Testing air leakage volume (m3/h).
检验气体防护区的空气泄透量(m3/h)。
l Estimating natural leakage rate (aeration frequency 1/h).
估算气体防护区的自然泄透率（换气次数1/h）。
l Metering and testing the using effect of structural seal of the building and finding the leakage point with thermal imager and special chemical gas.
测量和检验气体防护区建筑结构密封的使用效果，配合热像仪及特殊化学气体寻找泄漏点。
l Assessing and classifying the door fan of the windows on-site according to the standars.
依据标准现场评价窗户的气密性和分级。
l Checking and calculating the effectiveness of the gas fire extinguishing system.
验算气体灭火系统实际灭火的有效性。
2. WORKING THEORY
工作原理
The system has a high output blower (fan) mounted in the airtight door which is used to make a pressure deference between outside and inside of the building by increasing or decreasing the pressure. Such pressure deference makes air flowing in the envelope of the building. The system meters the door fan of the whole building envelope by metering the pressure changing volume made by the blower.
本系统包括一个大功率的鼓鼓风机（风扇）安装在密封门上。通过鼓鼓风机对房屋迚行加压和减压使房屋内外有一个压力差。这个压力差可以使空气在房屋的外围结构之间流动，通过测量鼓鼓风机对室内压力的改变量，系统可以测量整个房屋围护结构的气密性。
A typical building door fan test includes a series of tests under different pressures from 60 Pa to 10 Pa and gets a series of data for the changes during the air pressure changing from high to low.
一个典型的建筑物气密性测试包括从60帕斯卡到10帕斯卡之间的一系列的不同压力的测试。测出当气压从高到低的变化时的一系列数据。
The system can make air through the small wholes connecting to the outside and make it easy to find the leakage point with special chemical gas and tools such as thermal mapper. The door fan test is also used to check if the building needs ventilation structure.
本系统可以使气体迚入所有不外界相通的小孔中，这使得我们可以借助于特殊的化学气体、红外线热成像仪等工具轻易的找到泄漏点。气密性检测还可以用来确定房屋是否需要通风结构等。
