Portable Gas Detectors Categories and Differences Portable detectors can be divided into pump-driven and diffusion types. Pump-driven gas d…
PortableGas DetectorsCategories and Differences
Portable detectors can be divided into pump-driven and diffusion types.
Pump-driven gas detectors are equipped with a small pump, which works by the power supply driving the pump to sample gas from the area to be tested and then send the gas to the instrument for detection. The characteristics of pump-driven gas detectors are fast detection speed, the ability to measure dangerous areas remotely to ensure maintenance personnel safety, and other features similar to diffusion gas detectors.
A diffusion gas detector is a device that allows the gas in the detection area to slowly flow freely in the air into the instrument for detection. This method is affected by the detection environment, such as ambient temperature and airflow. The characteristic of diffusion gas detectors is low cost.
The working principle of pump suction and diffusion gas detectors is basically the same. The instrument detects the sample gas through its sensor and then amplifies, organizes, and converts it through a circuit to display the corresponding value on the screen. Combustible gases commonly use catalytic combustion sensors, while toxic gases commonly use electrochemical sensors.
Portable gas detectorTechnical points
For many units, gas detection is a very important safety procedure. Many production processes involve gases that are potentially toxic, and some processes produce gaseous by-products that are hazardous. By performing regular equipment maintenance and inspection monitoring, these dangers can be detected early and controlled to a minimum.
The most outstanding feature of a portable gas detector is that it can detect various types of gases by replacing the corresponding sensor modules. There is no need to purchase a separate main unit for each type of gas; one detector can be used with different sensors to detect more than 30 different gases or vapors. The sensors are plug-and-play and do not require recalibration.
The sensor uses a new type of lightweight sensor module. Each sensor module is a composite device, containing a sensor, an amplifier, and a memory module. Based on this design, each sensor module can be independently calibrated and is plug-and-play. For example, when installed in a host machine, by inputting the corresponding calibration data into the microprocessor, no further adjustments are needed. In the future, when detecting gases, replacing the sensor each time does not require recalibration.
Precautions for Using Portable Gas Detectors
As a new favorite among gas detectors, portable gas detectors have continuously advanced with the maturation of gas detection technology. According to customer requirements and different usage scenarios, a portable gas detector can be equipped with multiple gas (inorganic/organic) sensors on a single main unit to achieve detection of a single gas or multiple gases. Portable gas alarms are characterized by their small size, light weight, fast response, and the ability to display the concentration of multiple gases simultaneously.
A. During the use of a portable gas detector, you should pay attention to regular calibration and inspection.
Currently, many gas detectors have replaceable sensors, but this does not mean that a detector can be freely used with different probes at any time. Whenever replacing a probe, in addition to a certain sensor activation time, the instrument must be recalibrated. In addition, it is recommended that before using any type of instrument, a response test with standard gas should be conducted to ensure that the instrument truly provides protection. Combustible gas detectors and toxic gas detectors, like other analytical testing instruments, use a relatively comparative method for measurement: first, the instrument is calibrated with zero gas and a standard concentration gas to obtain a standard curve stored in the instrument. During measurement, the electrical signal generated by the target gas concentration is compared with the electrical signal of the standard concentration to calculate the accurate gas concentration value. Therefore, performing zero calibration at any time and regular calibration of the instrument are essential tasks to ensure the accuracy of the measurements. It should be noted that:
B. Pay attention to detection interference between various sensors
Although composite gas detectors can detect multiple other gases simultaneously, portable gas detectors are not an arbitrary combination of toxic and harmful gases.
Generally speaking, each kindGas sensorEach corresponds to a specific gas to be detected, but no gas detector can be absolutely specific. Therefore, when choosing a gas sensor, it is necessary to understand as much as possible the detection interference of other gases on the sensor to ensure its accurate detection of a specific gas.
C. Pay attention to the lifespan of sensors in various portable gas detectors
All types of gas sensors have a certain service life, that is, a lifespan. Generally speaking, in portable instruments, LEL sensors have a relatively long lifespan and can usually be used for about three years; photoionization detectors have a lifespan of four years or more; electrochemical sensors for specific gases have a relatively short lifespan, generally between one to two years; oxygen sensors have the shortest lifespan, about one year. The lifespan of electrochemical sensors depends on their internal components.electrolyteIt dries out, so if it is not used for a long time, sealing it and storing it in a lower temperature environment can extend its lifespan to some extent. Fixed instruments, due to their relatively large size, also have a longer sensor lifespan. Therefore, sensors should be checked regularly and used within their valid period as much as possible, and replaced promptly once they fail.
D. Pay attention to the concentration measurement range of the gas detector:
Portable gas detectors have fixed detection ranges for various types of toxic and hazardous gas detectors. Only by completing measurements within its range can the instrument ensure accurate measurements. Measuring beyond the measurement range for a long time can cause permanent damage to the sensor. For example, a LEL detector, if accidentally used in an environment with more than 100% LEL exposure, can completely burn out the sensor. Toxic gas detectors can also be damaged if used for long periods at high concentrations. Therefore, if a fixed instrument emits an over-limit signal during use, the measurement circuit must be immediately turned off to ensure sensor safety.
Precautions for the above points during use of portable gas detectors will extend their service life and also improve measurement accuracy!
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