How to choose anemometer when conducting air conditioning system inspection
In air conditioning system testing, due to the large area of the air duct occupied by the impeller anemometer, it affects the distribution of air speed indoors or in pipelines, and has low sensitivity to low air speeds. Therefore, it is basically unusable. Many people find it inappropriate to purchase impellers because they are cheap. Wheeled structures are commonly used for outdoor testing, such as the green building standard which specifies that the wind speed in pedestrian areas around buildings should be below 5m/s, without affecting the comfort of outdoor activities and building ventilation.
Pitot Tube seems to be a method of measuring wind speed invented by a person named Pitot. The principle is to measure wind speed using dynamic pressure difference. The sensitivity of Pitot Tube mainly relies on the sensitivity of the micro pressure difference gauge it uses. Considering that the uncertainty of pressure difference below 1Pa is already very high (if interested, you can deduce the wind speed corresponding to 1Pa, which may be around 0.xm/s), its measurement accuracy is also limited. Another limitation is that the obtained value is the pressure difference, and users also need to convert the pressure difference.
If a digital micro pressure gauge with an accuracy higher than 1Pa is used, its price is also over ten thousand yuan, which is already close to that of an anemometer. If an alcohol inclined tube micropressure gauge is used, the domestic price that can ensure accuracy is also around a few hundred yuan, but anhydrous alcohol (with a purity of about 95%) must be used. If conducting air conditioning system testing business, it is necessary to calibrate the inclined tube micro pressure gauge for alcohol, which mainly involves calibrating the specific gravity of alcohol. However, long-term use of alcohol within a calibration cycle (usually 1 year) can easily evaporate, and after evaporation, it is difficult to ensure the calibration results of the inclined tube micro pressure gauge. Because air conditioning system testing requires on-site inspection, this type of inclined tube differential pressure gauge cannot be used in many modes of transportation due to constraints such as air traffic control.
In short, although the Pitot tube+inclined tube micro differential pressure gauge is a cheap configuration, its operation, use, and calibration are very cumbersome to achieve ideal wind speed measurement accuracy. If a Pitot tube and a digital micro pressure gauge are used, the price is actually similar to that of an anemometer. The advantage is that the high-precision micro pressure gauge used here can also measure micro pressure differences and perform measurements of other physical quantities.
