Gas sensor range standard method

Gas sensor is a kind of common product type of sensor, has the flexibility, high reliability, easy maintenance, long life and other advantages, is widely used in many fields. Today engineering mainly introduce gas sensor range calibration method, hope that can help users better application products.

A calibration gas premixed

premixed gas is gas sensor calibration and one of the most popular method of choice. Premixed calibration gas can be compressed and stored under certain pressure of a cylinder. These bottles can be any size, but in the field calibration, people like small in size and light gas cylinders. These small and with a cylinder can be divided into two categories: low pressure and high pressure gas equipment. Low pressure cylinder thin light weight bottle wall is usually not recycling and one-off. High pressure cylinder is designed for pure hazardous chemicals. For the calibration gases, the cylinders usually wall is very thick, can withstand pressure to 2000 psi. For sensor calibration, high pressure gas outflow from the high pressure cylinder, need a pressure reducer. It is by the pressure controller, pressure gauge, flow of current limiting hole. Traffic current limiting hole is a given, under the pressure of the allowed a certain amount of air flow for the tiny thread hole. In the process of calibration, in order to get the proper reading, some require a moisture sensor. The humidifying process steps with sensor zero setting.

B, osmosis equipment

osmosis device is an airtight container, equipped with gas liquid equilibrium chemical. The edge of the gas molecules through osmosis container or roof penetration. The permeation rate of the gas depends on temperature and permeability of the material. Permeability is stable for a long period of time. Mixed with osmosis chemicals formed a constant calibration gases, knew the permeability after temperature is given. This will require a constant diameter measuring device and flow controller. Penetration tube continuously at a constant rate, however, conveying chemicals, as the storage and security issues. Given the permeability of the gas for application may be too high or too low. For example, high vapor pressure of gas permeability fast and very low vapor pressure gas chemicals has low permeability and no any purpose. Most infiltration equipment can be found in the lab, often applied in the analysis instrument. The concentration of the need for gas monitoring, sensor calibration is a typical high permeability equipment. So its application is limited.

C, cross calibration

using the method of cross calibration, each sensor is mainly subjected to the interference of other gases. For example, to calibrate 100% LEL ethane gases, usually with 50% ELE methane gas instead of the actual ethane gases. This is because the oxide is a liquid at room temperature with low vapor pressure. Therefore said the use of precise mixture and keep it in high pressure is difficult. In other words, the vapor pressure of methane has the very high and very stable. In addition, it can be mixed with air and maintain under high pressure. Compared with the oxide mixture of methane can be used to more calibration, at the same time it has a long life. 50% of the oxide mixture is easy to get. Therefore, combustible gas alarming device manufacturers recommend the use of methane as a substitute for calibration of other gases. There are two ways to complete the methane as a substitute for calibration of other gases. The first method is to use methane calibration combustible gas alarming device, at the same time, multiply the readings obtained by manual response factor instead of other gases from the readings. Such is the most commonly used type of catalytic sensor. Line is type catalytic sensor is output, so the application of the response factor in line with the full scale range. For example, when the use of methane sensor calibration, the pentane output is only half of the methane. Therefore the response factor of pentane is 05. So when the actual detection pentane and methane sensor calibration, reading times the 05 for pentane readings. The second method is still used as calibration gas, methane but calibration readings for a double value. For example, USES 50% LEL of methane gas calibration 100% LEL pentane. Although used in calibration is methane gas, instrument calibration, after its readings for pentane gas concentration. Many low range and harmful gas sensor can be used to cross calibration gases. Also, infrared detectors for any gas in the same wavelength is absorbed, can use the method of cross calibration. Cross calibration method has the advantage of allowing the sensor calibration using a gas range easy access and handling. Use the method of cross calibration, however, also can appear some problems. One is the response factor of each sensor is different, because it is impossible to make every sensor in manufacturing sensors. For example, type in the catalytic sensor, heater voltage has instructions in the manual. Another response factor can't be used. Response characteristics will be set up with the heater voltage varies. Therefore, using the actual target gas sensor calibration cycle detection is a kind of good method. Stable nonflammable and non-toxic concentration of various gases can be obtained from the supplier. Details please contact the instrument manufacturers.

D gas mixture

all calibration gases are not available. Even if it is available, it is also possible in a certain concentration or fixed under the background of the mixture, the calibration gas is not available. However, many of the mixture can be diluted, the monitor of gas of low concentration range calibration.

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