When selecting the sensor of the flammable gas detector

Update:15-06-2019
Summary:

When selecting the sensor of the flammable gas detector […]

When selecting the sensor of the flammable gas detector, we should first determine the measurement target and the measurement environment. Even if the same physical quantity is measured, there are many kinds of sensors available, and which one is more suitable. It is necessary to consider the following specific problems according to the characteristics of the measurement and the operating conditions of the sensor: the size of the range; the demand for the sensor volume by the measured orientation; the measurement method is touch-type and right-touch; the signal is extracted, wired or Wrong touch measurement; the origin of the sensor, domestically produced is still imported, the quotation can be accepted, still self-developed. These are the things we should think about.

Then it is its stability, the so-called stability, that is, the sensor of the combustible gas detector can adhere to an outstanding situation for a long time in the process of long-term use, under the influence of environmental factors that have a great influence on it. , has a strong ability to adapt.

Another important point to compare is the accuracy of the measurement of the sensor of the gas detector. As an important performance index of the sensor, it is an important part of the accurate measurement system. Of course, the sensor is proportional. The higher the accuracy of the measurement, the more expensive the quotation is. If it is for quantitative analysis, it is necessary to obtain accurate measurement values, and it is necessary to select a sensor whose accuracy level can meet the demand. If the measurement intention is qualitative analysis, the sensor with high repeatability can be selected, and the accuracy of the positive value is not suitable.

In addition to the three points described above, there is the linear scale, frequency response characteristics, sensitivity, etc. of the flammable gas detector sensor, so we will not analyze them one by one.

Problems to be aware of when using a flammable gas detector

1: Pay attention to frequent calibration and testing. The toxic and harmful gas detectors are also measured in a relatively comparative manner, as are other analytical instruments: the instrument is first calibrated with a zero gas and a standard concentration of gas, and a standard curve is stored in the instrument. During the measurement, the instrument compares the electrical signal generated by the gas concentration to be measured with the electrical signal of the standard concentration, and calculates an accurate gas concentration value. Therefore, zero calibration of the instrument at any time and regular calibration of the instrument are essential tasks to ensure accurate measurement of the instrument. It should be noted that many gas detectors can replace the detection sensor at present, but this does not mean that one detector can be equipped with different detector probes at any time. Whenever the probe is replaced, in addition to a certain sensor activation time, the instrument must be recalibrated. In addition, it is recommended that the instrument be responsive to the instrument before it is used to ensure that the instrument actually protects.

2: Pay attention to the detection interference between various sensors. In general, each sensor corresponds to a specific test gas, but any gas detector cannot be absolutely special. Therefore, when selecting a gas sensor, it should be as close as possible to the detection interference of other gases to the sensor to ensure its accurate detection of a specific gas.

3: Pay attention to the life of various types of sensors: All kinds of gas sensors have a certain service life, that is, life. Generally speaking, in portable instruments, LEL sensors have a long life and can be used for about three years; photoionization detectors have a life span of four years or longer; electrochemical specific gas sensors have a relatively short life span. In one to two years; the life of the oxygen sensor is the shortest, about a year or so. The life of an electrochemical sensor depends on the dryness of the electrolyte, so if it is not used for a long time, it can be extended to a lower temperature environment to extend the service life. Due to the relatively large size of the fixed instrument, the life of the sensor is also longer. Therefore, the sensor should be tested at any time, as much as possible during the life of the sensor, and if it fails, replace it in time.

4: Pay attention to the concentration measurement range of the test instrument: All kinds of toxic and harmful gas detectors have their fixed detection range. Only when the measurement is completed within its measurement range can it be guaranteed. The instrument is accurately measured. Long-term measurement beyond the measurement range may cause permanent damage to the sensor. For example, the LEL detector may burn the sensor completely if it is used in an environment exceeding 100% LEL. The toxic gas detector can cause damage when used for a long time at a higher concentration. Therefore, if the stationary instrument emits an over-limit signal during use, the measurement circuit should be turned off immediately to ensure the safety of the sensor. Table of gas detector concentration detection range, resolution, allowable concentration and maximum withstand concentration (ppm)