A common mistake of hvac duct sensor installation

On installation hvac sensor are described in a series of common mistakes in blog articles, this article is the second essay (three), focus on physical measurement error caused by incorrect installation.It will mainly discuss common hvac duct sensor installation errors.

Temperature difference

Important source of measurement error for pipe sensor is pipe inside and outside air temperature difference, for example, if you try to install the pipe sensor to measure the outdoor air in the intake pipe.Pipeline and outside temperatures usually, there is a big temperature difference between heat flowing through a pipe, which indicates a measurement of temperature increase or decrease.Humidity measurements, of course, also have deviation, especially under the condition of the temperature difference is very big.If the humidity is high, in the piping and pipe outside temperature is low, can cause condensation.Low velocity, the effect of external heat leakage from the pipe.In order to obtain accurate measurement results, be sure to avoid any of these.

Be very careful when using insulation pipeline, because they will increase the temperature difference between the pipe and the environment.You may need to cut the sensor of the insulating layer and put it in a special insulating layer, so that the electronic device shell is closer to the temperature of the pipe.The shorter insertion depth will also enhance the effect.Temperature difference是管道传感器测量误差的常见来源。

Dead space to install

Installed in the corner is common pipe sensor (figure 1).In this case, the competent road airflow in fact no sensor through the pipe, so the measurement of the air does not represent the competent road air humidity and temperature.To avoid this problem, should be directly to the sensor is installed in the main flow channel.When the pipes are in a high humidity and low velocity, even more so.

Figure 1. The installation of pipe sensor in the corner, lead to inaccurate measurements

condensation

Under the condition of the condensation may occur, install the sensor down will make things worse.condensation通常发生在管道传感器安装到管道的地方，如果传感器朝下安装，冷凝水将顺着传感器探杆向下流入传感器并导致读数不准确 – 甚至可能导致腐蚀或永久损坏传感器。传感器应水平安装，如果必须倾斜，请确保向上倾斜而不是向下倾斜。

Humidity sensors are usually used to control the humidity.For example, spray humidifier spray droplets, these droplets need some time to evaporate.If the pipe sensor is installed near the humidifier too, will cause the water to spray into the humidity or temperature sensors.These droplets are cumulative, condensation of sensor will affect the accuracy of measurement.In the worst cases, the sensor may be completely damaged;At least, if the sensor is often affected by condensation, then its measured value is not appropriate to use them to control.Humidifier and the shortest distance between pipe sensor depends on the velocity and humidifier types, but in general, pipe sensor installation position should be from the humidifier about five meters.

When installing pipeline transmitter usually play a through hole, in order to later can use reference probe to check readings (figure 2).Do not use the tape to cover the hole when available.

Figure 2. When installing pipe transducer a through hole, in order to use reference probe check readings.

For the CO₂Sensor and gas sensor, a common design is the so-called traffic capture.This refers to when a part of the pipeline flow is captured and directed to the electronic equipment measuring cavity, on the outside of the pipe perform the actual measurement.This part of the air and then return pipe, assume, cover and installed on the pipeline of the device itself is sealed.If there is a leak, the airflow will probably not into electronic equipment measuring cavity, so you measure is the outside air, instead of air in the pipe.

There are some designed for measuring sensor in the pipe, they are less likely to happen leakage caused by mistake.

Please continue to pay attention to our blog posts in January, it introduces the installation for measuring the hvac outdoor humidity sensor and CO₂A common errors of a sensor.

For more information about hvac duct sensor:HMDS/W80,HMDS/W110andHMD60.