gas detectorCalibration refers to placing the instrument in a test gas at a corresponding known concentration and comparing the test results with the gas concentration to understand the accuracy of the instrument. For example, n-hexane burns and explodes at 1.1% volume, and when a 10% alarm is set on the n-hexane detector, it alarms when the n-hexane concentration reaches 0.1%. For catalytic combustion sensors, the concentration is low. The toxic gas alarm value is much lower than the flammable gas alarm value. For chlorine, the threshold alarm value is only 0.5 ppm.
gas detectorChoose a bus system or a branch system and determine it according to the actual working conditions.
1. If the number of probes exceeds 8, it is recommended to use a bus system. In this way, the difficulty and cost of wiring can be reduced. All probes are contained in the main unit via a single cable, theoretically connecting more probes. If the number is less than 8, a wiring system can be selected, with each probe connected to the main unit via a separate cable.
2. distance. Under actual working conditions, because the installation position of each probe and the distance between the probes are far to near, it is recommended to use a bus system when the distance is long. The bus system generally has a transmission distance of 1-2km, only one trunk cable needs to be laid, and all probes can be connected to the trunk line. In addition, the transmission distance of RS485 can be increased by adding repeaters, which is theoretically unlimited. In the case of shorter distances, a breakout system is used.
3. Signal processing needs. In many cases, the assay data needs to be processed multiple times. 4-20mA is the standard industrial signal, which can be connected to various PLC and DCS systems. However, RS485 signals are required when data needs to be saved and displayed twice.
Advantages of the bus system:
The signal is unified and the probability of failure is low. The bus control system does not have this inconvenience. It transmits data in the same form over the data line, improving data reliability.
Simple wiring and low workload. The significant advantages of the bus system are less wiring, simple wiring, and low cost. Four-bus system, two signal lines, two power lines, simple and convenient wiring.
Advantages of the distribution system
Good data synchronization. Compared to the bus system, per unitgas detectorIndependent communication with the controller can transmit the on-site situation to the control part in time, so that the monitoring personnel can make timely and effective judgments, and the corresponding peripheral control equipment can make corresponding control actions in a timely and effective manner, so as to avoid the occurrence of dangerous accidents.