(1) The method of selecting the measurement range is the same as measuring the weight and temperature. When selecting the humidity sensor, the measurement range must be determined first. In addition to meteorological and scientific research departments, high-temperature, humidity measurement and control generally do not need to measure the entire wet process (0-100% RH).
(2) Method of Selecting Measurement Accuracy The measurement accuracy is the most important indicator of the humidity sensor, because for each percentage increase, the humidity sensor is on a step, or even a grade. Because of the need to achieve different levels of precision, the resulting manufacturing costs vary widely and the price difference is very far. Therefore, buyers must tailor their clothes to avoid blindly pursuing “high, refined, and sharpâ€. If the humidity sensor is used at different temperatures, the indication must also consider the effect of temperature drift. It is well-known that relative humidity is a function of temperature and that the temperature affects the relative humidity in a given space. Each temperature changes by 0.1°C. A humidity change (error) of 0.5% RH will be generated. If it is difficult to use a constant temperature in the occasion of use, it is not suitable to propose excessively high humidity measurement accuracy. In most cases, the accuracy of ±5% RH is sufficient if there is no accurate temperature control method or if the space under test is unsealed. For those applications that require precise control of constant temperature, humidity, or humidity, or need to track and record changes in humidity at any time, use a humidity sensor with an accuracy of ±3% RH or more. Accuracy higher than ±2% RH is not even a standard humidity generator for calibration sensors, let alone the sensor itself. Relative humidity measuring instruments, even at 20-25 °C, to achieve 2% RH accuracy is still very difficult. The characteristics given in the general product literature are measured at room temperature (20 °C ± 10 °C) and clean gas.
(3) Considering time drift and temperature drift In actual use, due to the influence of dust, oil and harmful gases, the electronic humidity transmitter will age and the accuracy will decline due to the long use time. The annual drift of the electronic humidity transmitter is generally small. All are within ±2% or even higher. Under normal circumstances, the manufacturer will indicate that the effective time for 1 calibration is 1 year or 2 years, and that it needs to be re-calibrated.
(4) Other precautions The humidity sensor is non-hermetic. To protect the accuracy and stability of the measurement, it should be avoided in acidic, alkaline, and organic solvent-containing atmospheres. Also avoid using in dusty environments. In order to correctly reflect the humidity of the space to be measured, it is also necessary to avoid placing the sensor too close to the wall or in a corner where air does not flow. If the room being measured is too large, multiple sensors should be placed. Some humidity sensors require a relatively high power supply, otherwise it will affect the measurement accuracy. Or the sensors can interfere with each other and they can't even work. When used, provide suitable power supply that meets the accuracy requirements according to technical requirements. When the sensor needs to carry out long-distance signal transmission, it is necessary to pay attention to signal attenuation. When the transmission distance exceeds 200m, it is recommended to use the humidity sensor of the frequency output signal.
Shanghai Fanmai Industrial Development Co., Ltd. is currently a number of well-known foreign brand agents, focusing on the marketing and sales of imported sensors, instrumentation, and adhere to the development direction of multi-species, multi-brand, differentiated and enthusiastic service. Welcome customers to negotiate.
Air Preheaters (APH)
An air preheater (APH) is a device used to heat air, commonly used in industrial boilers, thermal power plants, and other thermal energy facilities. APH improves the thermal efficiency of the boiler by transferring heat from the flue gas to the air entering the boiler through heat exchange with it.
APH usually consists of a Heat Exchanger with a number of parallel pipes inside the exchanger through which smoke and air flow to allow heat exchange. In APH, the smoke flows on the outside of the heat exchanger and the air flows on the inside so that the heat between the smoke and the air can be transferred through the pipe walls.
The main business scope is various heaters, waste heat boilers, pressure vessels, supportingair preheaters, air coolers, furnace accessories and accessories, and provide equipment installation, with EPC ability of projects. At present, our customers have covered all large and medium-sized petrochemical enterprises in China and established long-term strategic cooperative partnership with them. Products are exported to Southeast Asia, Middle East, and other regions.
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